Aerosol generating device including an induction heating array including first and second inductor coils

Abstract

An aerosol generating device comprises: an induction heating array configured to heat an aerosol forming substrate, wherein the induction heating array comprises a susceptor array capable of being heated by penetrating a variable magnetic field to heat the aerosol forming substrate, at least a first inductor coil, and at least a second inductor coil, and a controller, wherein the controller is configured to drive the first inductor coil with a first alternating pulse width modulation signal to generate a first alternating magnetic field to heat a first portion of the susceptor array, wherein the controller is configured to drive the second inductor coil with a second alternating pulse width modulation signal to generate a second alternating magnetic field to heat a second portion of the susceptor array, and wherein the controller is configured to supply the first alternating pulse width modulation signal and the second alternating pulse width modulation signal with a complementary duty cycle. An aerosol generating system comprising an aerosol generating device and an aerosol generating article comprising an aerosol forming substrate.

Description

Technology Field

[0001] The present disclosure relates to an aerosol generator having an induction heating array, a method for controlling an aerosol generator having an induction heating array, and an aerosol generator system including an aerosol generator having an induction heating array. Background Technology

[0002] A number of electrically operated aerosol generating systems are proposed in the art in which an aerosol generating device having an electric heater is used to heat an aerosol-forming substrate, such as a cigarette plug. One objective of such aerosol generating systems is to reduce known harmful smoke components of the type produced by the combustion and thermal degradation of tobacco in conventional cigarettes. Typically, the aerosol generating substrate is provided as part of an aerosol generating article that is inserted into the chamber or cavity of the aerosol generating device. In some known systems, a resistive heating element, such as a heating blade, is inserted into or around the aerosol-forming substrate when the article is received in the aerosol generating device in order to heat the aerosol-forming substrate to a temperature at which it is possible to release volatile components capable of forming an aerosol. In other aerosol generating systems, an induction heater is used rather than a resistive heating element. The induction heater typically comprises an inductor coil that forms part of the aerosol generating device and a susceptor element arranged to be thermally close to the aerosol-forming substrate. The inductor heats the aerosol-forming substrate by generating a variable magnetic field to cause eddy currents and hysteresis losses in the susceptor, thereby heating the susceptor. Induction heating can allow aerosols to be generated without exposing the heater to the aerosol-generating article. This can improve the ease with which the heater can be cleaned.

[0003] Some disclosed aerosol generators include two or more inductor coils, each inductor coil arranged to heat different parts of a susceptor. Such aerosol generators can be used to heat different parts of an aerosol generating article at different times or at different temperatures. However, it may be difficult for such an aerosol generator to heat a part of an aerosol generating article without also indirectly heating an adjacent part of the aerosol generating article.

[0004] It would be desirable to provide an aerosol generating device that mitigates or overcomes these problems of the disclosed system.

[0005] According to the present invention, an aerosol generating device is provided, comprising an induction heating array configured to heat an aerosol forming substrate, the induction heating array comprising at least a first inductor coil and at least a second inductor coil, wherein the induction heating array is configured to heat the aerosol forming substrate by penetrating with a variable magnetic field to heat the aerosol forming substrate, said induction heating array

[0006] As used herein, the term "duty cycle" refers to the amount of time a signal is turned on and the amount of time a signal is turned off. The duty cycle is given as a percentage. A 60% duty cycle means that the signal is turned on for 60% of the time and the signal is turned off for 40% of the time.

[0007] As used herein, the term "complementary duty cycle" refers to two signals, wherein one signal is turned on while the other signal is turned off. The signals may have a sawtooth pattern in which the second signal has a sawtooth pattern opposite to that of the first signal. The combined signals may result in a continuous AC current.

[0008] In some embodiments, the duty cycles of the first and second signals shift gradually. That is, the duty cycle of the first signal may be decreased, while the duty cycle of the second signal may be increased or vice versa.

[0009] The controller may be configured to supply a first alternating pulse width modulation signal to a first inductor coil during a first stage to increase the temperature of a first part of the susceptor array from an initial temperature to a first operating temperature, and the controller is configured to supply the first alternating pulse width modulation signal during the first stage with a duty cycle of more than 50%, preferably more than 60%, preferably more than 70%, more preferably more than 80%, most preferably more than 90%.

[0010] The controller may be configured to supply a first alternating pulse width modulation signal to a first inductor coil during a second step to reduce the temperature of a first part of the susceptor array from a first operating temperature to a second operating temperature, and the controller is configured to supply the first alternating pulse width modulation signal during the second step with a duty cycle of less than 50%, preferably less than 40%, preferably less than 30%, more preferably less than 20%, and most preferably less than 10%.

[0011] The controller may be configured to supply the second alternating pulse width modulation signal to the second inductor coil during the first step to increase the temperature of the second part of the susceptor array from an initial temperature to a third operating temperature lower than the first operating temperature, and the controller is configured to supply the second alternating pulse width modulation signal during the first step with a duty cycle of less than 50%, preferably less than 40%, preferably less than 30%, more preferably less than 20%, most preferably less than 10%.

[0012] The controller may be configured to supply a second alternating pulse width modulation signal to a second inductor coil during a second step to increase the temperature of the second part of the susceptor array from the third operating temperature to a fourth operating temperature higher than the second operating temperature, and the controller is configured to supply the second alternating pulse width modulation signal during the second step with a duty cycle of more than 50%, preferably more than 60%, preferably more than 70%, more preferably more than 80%, most preferably more than 90%.

[0013] The controller may be configured to supply a first alternating pulse width modulation signal with a duty cycle of more than 80% during the first stage, and the controller is configured to supply a second alternating pulse width modulation signal with a duty cycle of less than 20% during the first stage.

[0014] The controller may be configured to supply a first alternating pulse width modulation signal with a duty cycle of more than 90% during the first stage, and the controller is configured to supply a second alternating pulse width modulation signal with a duty cycle of less than 10% during the first stage.

[0015] The controller may be configured to supply a first alternating pulse width modulation signal with a duty cycle of less than 20% during the second stage, and the controller is configured to supply a second alternating pulse width modulation signal with a duty cycle of more than 80% during the second stage.

[0016] The controller may be configured to supply a first alternating pulse width modulation signal with a duty cycle of less than 10% during the second stage, and the controller is configured to supply a second alternating pulse width modulation signal with a duty cycle of more than 90% during the second stage.

[0017] The aerosol generator may further include a power supply unit for providing power to an induction heating array.

[0018] The controller may include a microcontroller.

[0019] The microcontroller may be configured to use the clock frequency of the microcontroller as one or both of the alternating frequencies of the first alternating pulse width modulation signal and the second alternating pulse width modulation signal.

[0020] The aerosol generating device may further include an oscillator for generating one or both of the alternating frequencies of the first alternating pulse width modulation signal and the second alternating pulse width modulation signal.

[0021] The controller may further include an oscillator for generating one or both of the alternating frequencies of the first alternating pulse width modulation signal and the second alternating pulse width modulation signal.

[0022] The aerosol generating device may further include a first power stage, said first power stage including at least a first inductor coil and a first capacitor.

[0023] The first inductor coil and the first capacitor can be arranged as a first LC circuit.

[0024] The aerosol generating device may further include a second power stage, said second power stage including at least a second inductor coil and a second capacitor.

[0025] The second inductor coil and the second capacitor can be arranged as a second LC circuit.

[0026] According to the present invention, an aerosol generating system is provided, comprising an aerosol generating device according to the present invention and an aerosol generating article comprising an aerosol forming substrate.

[0027] According to the present invention, a method for controlling an aerosol generating device is also provided, wherein the aerosol generating device comprises: an induction heating array configured to heat an aerosol forming substrate, wherein the induction heating array comprises a susceptor array capable of being heated by penetrating a variable magnetic field to heat the aerosol forming substrate, at least a first inductor coil, and at least a second inductor coil, and a controller, wherein the controller is configured to drive the first inductor coil and the second inductor coil, and the method comprises: a step of driving the first inductor coil with a first pulse width modulation signal to generate a first alternating magnetic field for heating a first portion of the susceptor array, a step of driving the second inductor coil with a second pulse width modulation signal to generate a second alternating magnetic field for heating a second portion of the susceptor array, and a step of supplying the first pulse width modulation signal with a duty cycle complementary to the duty cycle of the second pulse width modulation signal.

[0028] A first alternating pulse width modulation signal may be supplied to a first inductor coil during a first stage to increase the temperature of the first part of the susceptor array from an initial temperature to a first operating temperature, and the first alternating pulse width modulation signal is supplied during the first stage with a duty cycle of more than 50%, preferably more than 60%, preferably more than 70%, more preferably more than 80%, most preferably more than 90%.

[0029] A first alternating pulse width modulation signal may be supplied to a first inductor coil during a second step to reduce the temperature of the first part of the susceptor array from the first operating temperature to the second operating temperature, and the first alternating pulse width modulation signal is supplied during the second step with a duty cycle of less than 50%, preferably less than 40%, preferably less than 30%, more preferably less than 20%, most preferably less than 10%.

[0030] A second alternating pulse width modulation signal may be supplied to a second inductor coil during the first step to increase the temperature of the second part of the susceptor array from an initial temperature to a third operating temperature, and the second alternating pulse width modulation signal is supplied during the first step with a duty cycle of less than 50%, preferably less than 40%, preferably less than 30%, more preferably less than 20%, and most preferably less than 10%.

[0031] A second alternating pulse width modulation signal may be supplied to the second inductor coil during the second stage to increase the temperature of the second part of the susceptor array from the third operating temperature to the fourth operating temperature, and the second alternating pulse width modulation signal is supplied during the second stage with a duty cycle of more than 50%, preferably more than 60%, preferably more than 70%, more preferably more than 80%, most preferably more than 90%.

[0032] The first alternating pulse width modulation signal can be supplied during the first stage with an 80% duty cycle, and the second alternating pulse width modulation signal is supplied during the first stage with a 20% duty cycle.

[0033] The first alternating pulse width modulation signal can be supplied during the first stage with a duty cycle of 90%, and the second alternating pulse width modulation signal is supplied during the first stage with a duty cycle of 10%.

[0034] The first alternating pulse width modulation signal can be supplied during the second stage with a duty cycle of 20%, and the second alternating pulse width modulation signal is supplied during the second stage with a duty cycle of 80%.

[0035] The first alternating pulse width modulation signal can be supplied during the second stage with a duty cycle of 10%, and the second alternating pulse width modulation signal is supplied during the second stage with a duty cycle of 90%.

[0036] As used herein, the term "aerosol-forming substrate" relates to a substrate capable of releasing volatile compounds capable of forming an aerosol. These volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may generally be part of an aerosol-generating article.

[0037] As used herein, the term “aerosol generating article” refers to an article comprising an aerosol-forming material capable of releasing a volatile compound capable of forming an aerosol. For example, an aerosol generating article may be an article that generates an aerosol that can be inhaled directly by a user inhaling or puffing over a mouthpiece at the proximal end of the system or at the user-side end. An aerosol generating article may be disposable. An article comprising an aerosol-forming material containing tobacco may be referred to herein as a tobacco stick.

[0038] As used herein, "aerosol generating device" refers to a device that generates an aerosol by interacting with an aerosol-forming substrate.

[0039] As used herein, the term "aerosol generating system" refers to a combination of an aerosol generating device and an aerosol generating article. In an aerosol generating system, the aerosol generating article and the aerosol generating device cooperate to generate breathable aerosols.

[0040] As used herein, the term "variable current" includes any current that varies over time to generate a variable magnetic field. The term "variable current" is intended to include alternating current. When the variable current is alternating current, the alternating current generates an alternating magnetic field.

[0041] As used herein, the term "length" refers to the main longitudinal dimension of an aerosol generating device or an aerosol generating article, or a component of an aerosol generating device or an aerosol generating article.

[0042] As used herein, the term "width" refers to the main transverse dimension of an aerosol generating device or aerosol generating article, or a component of an aerosol generating device or aerosol generating article. The term "thickness" refers to the transverse dimension perpendicular to the width.

[0043] As used herein, the term “transverse section” is used to describe a cross-section of an aerosol generating device or aerosol generating article, or a component of an aerosol generating device or aerosol generating article, in a direction perpendicular to the longitudinal direction at a specific location along its length.

[0044] As used herein, the term "proximal" refers to the user end or mouse end of an aerosol generator or aerosol generating article. The proximal end of a component of an aerosol generator or aerosol generating article is the end of the component closest to the user end or mouse end of the aerosol generator or aerosol generating article. As used herein, the term "distal" refers to the end opposite to the proximal end.

[0045] The first stage may have a predetermined duration. The second stage may have a predetermined duration. The duration of the first stage and the duration of the second stage may be the same. The duration of the second stage may differ from the duration of the first stage. Advantageously, this enables the system to heat the first portion of the aerosol-forming substrate and the second portion of the aerosol-forming substrate for different periods of time. The duration of the second stage may be shorter than the duration of the first stage. The duration of the second stage may be longer than the duration of the first stage.

[0046] The duration of the first stage may be approximately 50 seconds to approximately 200 seconds. The duration of the second stage is approximately 50 seconds to approximately 200 seconds. The combined duration of the first and second stages may be approximately 100 seconds to approximately 400 seconds. The combined duration of the first and second stages may be approximately 150 seconds to approximately 300 seconds.

[0047] In some embodiments, the system further includes a puff detector configured to detect when a user puffs the system to receive an aerosol. In these embodiments, the duration of the first stage may be based on a first predetermined number of puffs detected by the puff detector. The first predetermined number of puffs may be 2 to 5. In these embodiments, the duration of the second stage may be based on a second predetermined number of puffs detected by the puff detector. The second predetermined number of puffs may be 2 to 5. In these embodiments, the combined duration of the first and second stages may be based on a combined predetermined number of puffs detected by the puff detector. The combined predetermined number of puffs may be 3 to 10 user puffs.

[0048] In some preferred embodiments, the first step is terminated earlier after a first maximum puff number is detected or when a first maximum duration is reached. The first maximum puff number may be 2 to 5, and the first maximum duration is 50 seconds to about 200 seconds.

[0049] In some preferred embodiments, the second step is terminated earlier after the second maximum number of puffs is detected or when the second maximum duration is reached. The second maximum number of puffs may be 2 to 5, and the second maximum duration may be 50 seconds to about 200 seconds.

[0050] The first alternating pulse width modulation signal can be controlled so that the temperature of the first section of the susceptor array increases from an initial temperature according to the first operating temperature profile. The first temperature profile is a predetermined desired temperature of the first section of the susceptor array over time. At any given point in time, when the actual temperature of the first section of the susceptor array differs from the temperature of the first temperature profile at that point in time, the first alternating pulse width modulation signal is adjusted to adjust the temperature of the first section of the susceptor array to the temperature specified by the first temperature profile at that point in time.

[0051] Similarly, the second alternating pulse width modulation signal can be controlled to increase the temperature of the second section of the susceptor array from the initial temperature according to the second temperature profile. The second temperature profile is a predetermined desired temperature of the second section of the susceptor array over time. At any given point in time, when the actual temperature of the second section of the susceptor array differs from the temperature of the second temperature profile at that point in time, the second alternating pulse width modulation signal is adjusted to adjust the temperature of the second section of the susceptor array to the temperature specified by the second temperature profile at that point in time.

[0052] In some embodiments, the first operating temperature profile is substantially constant. In some embodiments, the first operating temperature profile varies over time.

[0053] In some embodiments, the second operating temperature profile is substantially constant. In some embodiments, the second operating temperature profile varies over time.

[0054] In some embodiments, at least in part of the first stage, the first operating temperature profile is greater than the second operating temperature profile. In these embodiments, at least in part of the first stage, the first operating temperature profile is greater than the second operating temperature profile by at least about 50°C. The first operating temperature profile may be greater than the second operating temperature profile throughout the entire first stage.

[0055] In some embodiments, in the second step, the first operating temperature profile and the second operating temperature profile are substantially the same. In some embodiments, in the second step, the second operating temperature profile is within about 5°C of the first operating temperature profile.

[0056] In some embodiments, at least a portion of the second step, the second operating temperature profile is greater than the first operating temperature profile. In these embodiments, in the second step, the second operating temperature profile may be greater than the first operating temperature profile by about 50°C or less.

[0057] In some embodiments, the first operating temperature profile is substantially constant for at least a portion of the first stage. The first operating temperature profile may be constant during the first stage.

[0058] In some embodiments, the first operating temperature profile is substantially constant for at least a portion of the second stage. The first operating temperature profile may be constant during the second stage.

[0059] In some embodiments, the second operating temperature profile is substantially constant for at least a portion of the second stage. The second operating temperature profile may be constant during the second stage.

[0060] The first operating temperature profile may be about 180°C to 300°C for at least a portion of the first stage. The first operating temperature profile may be about 160°C to 260°C for at least a portion of the second stage. The second operating temperature profile may be about 180°C to 300°C for at least a portion of the second stage.

[0061] The susceptor array may have any suitable shape. The susceptor array may have a monolithic structure. The susceptor array may include multiple monolithic structures. The susceptor array may be elongated. The susceptor array may have any suitable cross-section. For example, the susceptor array may have a circular, elliptical, square, rectangular, triangular, or other polygonal cross-section.

[0062] In some embodiments, the susceptor array may include an internal heating element. As used herein, the term "internal heating element" refers to a heating element configured to be inserted into an aerosol-forming substrate.

[0063] In some embodiments, the susceptor array may be configured to penetrate the aerosol-forming substrate when the aerosol-forming substrate is received by the device. In these embodiments, the internal heating element is preferably configured to be insertable into the aerosol-forming substrate. The internal heating element may be in the form of a blade. The internal heating element may be in the form of a pin. The internal heating element may be in the form of a cone. If the aerosol generator includes a device cavity for receiving the aerosol-forming substrate, the internal heating element preferably extends into the device cavity.

[0064] In some embodiments, the susceptor array may be an external heating element. As used herein, the term "external heating element" refers to a heating element configured to heat the external surface of an aerosol-forming substrate. The external heating element is preferably configured to at least partially surround the aerosol-forming substrate when the aerosol-forming substrate is received by an aerosol generating device. The susceptor array may be configured to heat the external surface of the aerosol-forming substrate when the aerosol-forming substrate is received within the susceptor array cavity.

[0065] The susceptor array can be configured to substantially surround the aerosol-forming substrate when the aerosol-forming substrate is received by the device.

[0066] The susceptor array may include a cavity for receiving an aerosol-forming substrate. The susceptor array may include an outer side and an inner side facing the outer side. The outer side may at least partially define the susceptor array cavity for receiving the aerosol-forming substrate. A first part of the susceptor array may be tubular and may define a portion of the susceptor array cavity. A second part of the susceptor array may be tubular and may define a portion of the susceptor array cavity.

[0067] In some embodiments, the susceptor array includes a plurality of internal cavities for receiving an aerosol-forming substrate. An internal cavity of a first portion of the susceptor array may form a first cavity of the susceptor array, and an internal cavity of a second portion of the susceptor array may form a second cavity of the susceptor array.

[0068] In some preferred embodiments, the susceptor array comprises a single internal cavity for receiving an aerosol-forming substrate. In these embodiments, the internal cavity of the first part of the susceptor array defines a portion of the single internal cavity of the susceptor array, and the internal cavity of the second part of the susceptor array defines a second portion of the single internal cavity of the susceptor array. In some preferred embodiments, the susceptor array is a tubular susceptor array. The internal surface of the tubular susceptor array may define the susceptor array cavity.

[0069] In an embodiment in which an aerosol generating device includes a device cavity for receiving an aerosol forming substrate, a susceptor array may at least partially surround the device cavity. The susceptor array cavity may be aligned with the device cavity.

[0070] In some embodiments, the susceptor array includes at least one internal heating element and at least one external heating element.

[0071] The susceptor array includes at least one susceptor. The susceptor array may include a single susceptor. The susceptor array may be composed of a single susceptor. A first part of the susceptor array may include a first susceptor. A second part of the susceptor array may include a second susceptor.

[0072] As used herein, the term "susceptor" refers to an element comprising a material capable of converting electromagnetic energy into heat. When the susceptor is placed within a variable magnetic field, the susceptor is heated. The heating of the susceptor may be the result of at least one of hysteresis loss or eddy current induced in the susceptor, depending on the electrical and magnetic properties of the susceptor material.

[0073] The susceptor may comprise any suitable susceptor material. The susceptor may be formed of any material capable of being inductively heated to a temperature sufficient to aerosolize the aerosol-forming substrate. A preferred susceptor may be heated to a temperature exceeding 250°C. A preferred susceptor may be formed of an electrically conductive material. As used herein, "electrically conductive" means, at 20°C, 1 x 10⁻⁶ -4 It refers to a material having an electrical resistivity of Ωm or less. A preferred susceptor may be formed of a thermally conductive material. As used herein, the term “thermally conductive material” is used to describe a material having a thermal conductivity of at least about 10 W (W / (m·K)) per meter Kelvin at 23°C and 50% relative humidity as measured using the modified transient plan source (MTPS) method.

[0074] Materials suitable for the susceptor include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, nickel, nickel-containing compounds, titanium, and composites of metallic materials. Some preferred susceptors include metal or carbon. Some preferred susceptors include ferromagnetic materials, such as ferrite iron, ferromagnetic alloys like ferromagnetic steel or stainless steel, ferromagnetic particles, and ferrite. Some preferred susceptors are made of ferromagnetic materials. Suitable susceptors may include aluminum. Suitable susceptors may be composed of aluminum. The susceptor may contain at least about 5%, at least about 20%, at least about 50%, or at least about 90% of a ferromagnetic or paramagnetic material.

[0075] Preferably, the susceptor is formed of a material that is substantially impermeable to gases. That is, preferably, the susceptor is formed of a material that is not permeable to gases.

[0076] The susceptors in the susceptor array can have any suitable shape. For example, the susceptors can be elongated. The susceptors can have any suitable cross-section. For example, the susceptors can have circular, elliptical, square, rectangular, triangular, or other polygonal cross-sections.

[0077] A first part of the susceptor array may be a tubular susceptor. A second part of the susceptor array may be a tubular susceptor. The tubular susceptor includes an annular body that defines an internal cavity. The susceptor cavity may be configured to accommodate an aerosol-forming material. The susceptor cavity may be an open cavity. The susceptor cavity may be open at one end. The susceptor cavity may be open at both ends.

[0078] In some embodiments having multiple susceptors, each susceptor may be substantially identical. For example, a second susceptor may be substantially identical to a first susceptor. Each susceptor may be formed of the same material. Each susceptor may have substantially the same shape and dimensions. Making each susceptor substantially identical to another susceptor allows each susceptor to be heated to substantially the same temperature and heated at substantially the same rate when exposed to a given variable magnetic field.

[0079] In some embodiments, the second susceptor differs from the first susceptor in at least one feature. The second susceptor may be formed of a material different from the first susceptor. The second susceptor may have a shape and dimensions different from the first susceptor. The second susceptor may have a length greater than that of the first susceptor. Making each susceptor different from the other susceptors allows each susceptor to be adapted to provide optimal heat for different aerosol-forming substrates.

[0080] In one embodiment, the first aerosol-forming substrate may require heating to a first temperature to generate a first aerosol having desired characteristics, and the second aerosol-forming substrate may require heating to a second temperature different from the first temperature to generate a second aerosol having desired characteristics. In this embodiment, the first susceptor may be formed of a first material suitable for heating the first aerosol-forming substrate to the first temperature, and the second susceptor may be formed of a second material different from the first material suitable for heating the second aerosol-forming substrate to the second temperature.

[0081] In another embodiment, the aerosol generating article may comprise a first aerosol forming substrate having a first length and a second aerosol forming substrate having a second length different from the first length, so that heating the second aerosol forming substrate generates an amount of aerosol different from heating the first aerosol forming substrate. In this embodiment, the first susceptor may have a length substantially equal to the first length, and the second susceptor may have a length substantially equal to the second length.

[0082] In some preferred embodiments, the first susceptor is an elongated tubular susceptor, and the second susceptor is an elongated tubular susceptor. In these preferred embodiments, the first susceptor and the second susceptor can be substantially aligned. That is, the first susceptor and the second susceptor can be coaxially aligned.

[0083] A susceptor array may include any appropriate number of susceptors. A susceptor array may include multiple susceptors. A susceptor array may include at least two susceptors. For example, a susceptor array may include three, four, five, or six susceptors. If a susceptor array includes more than two susceptors, an intermediate element may be placed between each adjacent pair of susceptors.

[0084] In some preferred embodiments, the susceptor may include a susceptor layer provided on a support body. In an embodiment having a first susceptor and a second susceptor, the first susceptor and the second susceptor may each be formed of a support body and a susceptor layer. When the susceptor is placed in a variable magnetic field, eddy currents are induced very close to the surface of the susceptor due to an effect referred to as the skin effect. Thus, it is possible to form the susceptor from a relatively thin layer of susceptor material so that the susceptor is effectively heated in the presence of a variable magnetic field. Making the susceptor from a support body and a relatively thin susceptor layer can facilitate the manufacture of a simple, inexpensive, and robust aerosol-generating article.

[0085] The support body can be formed by a manufacturing process that is not sensitive to induction heating. Advantageously, this can reduce heating of the surface of the susceptor that does not come into contact with the aerosol-forming substrate, and the surface of the support body forms the surface of the susceptor that does not come into contact with the aerosol-forming substrate.

[0086] The support body may comprise an electrically insulating material. As used herein, "electrically insulating" means at least 1 x 10⁻⁶ at 20°C. 4 It refers to a material having an electrical resistivity of Ωm.

[0087] The supporting body may include a thermal insulator. As used herein, the term 'thermal insulating material' is used to describe a material having a bulk thermal conductivity of about 40 mW / (m·K) or less at 23°C and 50% relative humidity as measured using the modified transient plane source (MTPS) method.

[0088] Forming a support body from a thermal insulating material can provide a thermal insulating barrier between the susceptor layer and other components of the susceptor array, such as an inductor coil surrounding the susceptor array. Advantageously, this can reduce heat transfer between the susceptor and other components of the induction heating system.

[0089] The support body may be a tubular support body, and the susceptor layer may be provided on the inner surface of the tubular support body. By providing the susceptor layer on the inner surface of the support body, the susceptor layer is positioned adjacent to the aerosol-forming substrate within the cavity of the susceptor array, thereby improving heat transfer between the susceptor layer and the aerosol-forming substrate.

[0090] In some preferred embodiments having a first susceptor and a second susceptor, the first susceptor comprises a tubular support body formed of a thermal insulating material and a susceptor layer on the inner surface of the tubular support body. In some preferred embodiments, the second susceptor comprises a tubular support body formed of a thermal insulating material and a susceptor layer on the inner surface of the tubular support body.

[0091] The susceptor may be provided with a protective outer layer, for example, a protective ceramic layer or a protective glass layer. The protective outer layer may improve the durability of the susceptor and facilitate the cleaning of the susceptor. The protective outer layer may substantially surround the susceptor. The susceptor may include a protective coating formed by glass, ceramic, or an inert metal.

[0092] The susceptor array may include a separation portion between a first part of the susceptor array and a second part of the susceptor array.

[0093] The separation portion may be of any suitable size to thermally isolate the first portion of the susceptor array from the second portion of the susceptor array.

[0094] A susceptor array may include an intermediate element disposed between a first part of the susceptor array and a second part of the susceptor array. The intermediate element may be disposed within a separation portion between the first part of the susceptor array and the second part of the susceptor array. The intermediate element may extend between the first part of the susceptor array and the second part of the susceptor array. The intermediate element may contact the end of the first part of the susceptor array. The intermediate element may contact the end of the second part of the susceptor array. The intermediate element may be fixed to the end of the first part of the susceptor array. The intermediate element may be fixed to the end of the second part of the susceptor array. The intermediate element may connect the second part of the susceptor array to the first part of the susceptor array. When the intermediate element connects the second part of the susceptor array to the first part of the susceptor array, the intermediate element may provide a susceptor array having a structural support. Advantageously, the intermediate element can be provided as a single integral element that allows the susceptor array to be simply removed from and replaced from the induction heating array.

[0095] The intermediate element may have any suitable shape. The intermediate element may have any suitable cross-section. For example, the intermediate element may have a circular, elliptical, square, rectangular, triangular, or other polygonal cross-section. The intermediate element may be tubular. A tubular intermediate element includes an annular body that defines an internal cavity. The intermediate element may be configured to allow gas to permeate from the outside of the intermediate element into the internal cavity. The intermediate element cavity may be configured to accommodate a portion of an aerosol-generating article. The intermediate element cavity may be an open cavity. The intermediate element cavity may be open at one end. The intermediate element cavity may be open at both ends.

[0096] In some preferred embodiments, the first part of the susceptor array and the second part of the susceptor array are tubular susceptors, and the intermediate element is a tubular intermediate element. In these embodiments, the tubular first susceptor, the tubular second susceptor, and the tubular intermediate element may be substantially aligned. The tubular first susceptor, the tubular intermediate element, and the tubular second susceptor may be end-to-end arranged in the form of tubular rods. The internal cavities of the tubular first susceptor, the tubular intermediate element, and the tubular second susceptor may be substantially aligned. The internal cavities of the tubular first susceptor, the tubular intermediate element, and the tubular second susceptor may define the susceptor array cavity.

[0097] The intermediate element can be formed from any suitable material.

[0098] In a preferred embodiment, the intermediate element is formed of a material different from the first part of the susceptor array and the second part of the susceptor array.

[0099] The intermediate element may comprise a thermal insulating material for thermally insulating the first part of the susceptor array from the second part of the susceptor array. The intermediate element may comprise a material having a bulk thermal conductivity of about 100 mW / (m·K) or less at 23°C and 50% relative humidity, as measured using the modified transient plane source (MTPS) method. Providing an intermediate element formed of a thermal insulating material within the separation between the first part of the susceptor array and the second part of the susceptor array may further reduce heat transfer between the first part of the susceptor array and the second part of the susceptor array. Advantageously, this may improve the ability of the susceptor array to selectively heat individual parts of the aerosol-forming substrate. This also allows the size of the separation between the first part of the susceptor array and the second part of the susceptor array to be reduced, and subsequently allows the size of the susceptor array to be reduced.

[0100] The intermediate element may include an electrically insulating material for electrically insulating the first part of the susceptor array from the second part of the susceptor array. The susceptor, at 20°C, has at least 1 x 10 4 It may include a material having an electrical resistivity of Ωm.

[0101] The intermediate element may comprise at least one of: a thermal insulating material for thermally insulating a first portion of the susceptor array from a second portion of the susceptor array; and an electrical insulating material for electrically insulating a first portion of the susceptor array from a second portion of the susceptor array. In some preferred embodiments, the intermediate element comprises a thermal insulating material for thermally insulating a first portion of the susceptor array from a second portion of the susceptor array, and an electrical insulating material for electrically insulating a first portion of the susceptor array from a second portion of the susceptor array.

[0102] Materials particularly suitable for the intermediate element may include polymeric materials, such as polyetheretherketone (PEEK), liquid crystal polymers, such as Kevlar®, certain cements, glass, and ceramic materials, such as zirconium dioxide (ZrO2), silicon nitride (Si3N4), and aluminum oxide (Al2O3).

[0103] The intermediate element may be gas permeable. That is, the intermediate element is configured so that gas can pass through the intermediate element. Typically, the intermediate element is configured so that gas can pass from one side of the intermediate element to another side of the intermediate element. The intermediate element may include an outer side and an inner side facing the outer side. The intermediate element may be configured so that gas can pass from the outer side to the inner side.

[0104] In some embodiments, the intermediate element includes air passages configured to allow air to pass through the intermediate element. In these embodiments, the intermediate element may not need to be formed of a gas-permeable material. Accordingly, in some embodiments, the intermediate element is formed of a material that is not permeable to gas and includes air passages configured to allow air to pass through the intermediate element. The intermediate element may include a plurality of air passages. The intermediate element may include any suitable number of air passages, for example, two, three, four, five, or six air passages. If the intermediate element includes a plurality of air passages, the air passages may be regularly spaced apart on the intermediate element.

[0105] If the intermediate element is a tubular intermediate element defining an internal cavity, the intermediate element may include an air passage configured to allow air to flow from the outer surface of the intermediate element into the internal cavity. The intermediate element may include an air passage extending from the outer surface to the inner surface. If the tubular intermediate element includes a plurality of air passages, the air passages may be regularly spaced around the circumference of the tubular intermediate element.

[0106] The first inductor coil is configured such that a variable current supplied to the first inductor coil generates a variable magnetic field. The first inductor coil is arranged relative to the susceptor array such that a variable current supplied to the first inductor coil generates a variable magnetic field that heats a first portion of the susceptor array.

[0107] The second inductor coil is configured such that a variable current supplied to the second inductor coil generates a variable magnetic field. The second inductor coil is arranged relative to the susceptor array such that a variable current supplied to the second inductor coil generates a variable magnetic field that heats a second part of the susceptor array.

[0108] The inductor coil can have any suitable shape. For example, the inductor coil may be a flat inductor coil. A flat inductor coil may be wound spirally in a substantially flat plane. Preferably, the inductor coil is a tubular inductor coil defining an internal cavity. Typically, a tubular inductor coil is wound spirally around an axis. The inductor coil may be slender. Particularly preferably, the inductor coil may be a slender tubular inductor coil. The inductor coil may have any suitable cross-section. For example, the inductor coil may have a circular, elliptical, square, rectangular, triangular, or other polygonal cross-section.

[0109] The inductor coil can be formed of any suitable material. The inductor coil is formed of an electrically conductive material. Preferably, the inductor coil is formed of a metal or a metal alloy.

[0110] If the inductor coil is a tubular inductor coil, preferably, a portion of the susceptor array is arranged within the internal cavity of the inductor coil. Particularly preferably, the first inductor coil is a tubular inductor coil, and at least a portion of the first portion of the susceptor array is arranged within the internal cavity of the first inductor coil. The length of the tubular first inductor coil may be substantially similar to the length of the first portion of the susceptor array. Particularly preferably, the second inductor coil is a tubular inductor coil, and at least a portion of the second portion of the susceptor array is arranged within the internal cavity of the second inductor coil. The length of the tubular second inductor coil may be substantially similar to the length of the second portion of the susceptor array.

[0111] In some embodiments, the second inductor coil is substantially identical to the first inductor coil. That is, the first inductor coil and the second inductor coil have the same shape, dimensions, and number of turns. Particularly preferably, the second inductor coil is substantially identical to the first inductor coil in an embodiment where the second part of the susceptor array is substantially identical to the first part of the susceptor array.

[0112] In some embodiments, the second inductor coil is different from the first inductor coil. For example, the second inductor coil may have a different length, number of turns, or cross-section than the first inductor coil. Particularly preferably, the second inductor coil is different from the first inductor coil in an embodiment where the second part of the susceptor array is different from the first part of the susceptor array.

[0113] The first inductor coil and the second inductor coil may be arranged in any suitable arrangement. Particularly preferably, the first inductor coil and the second inductor coil are aligned coaxially along an axis. If the first inductor coil and the second inductor coil are slender tubular inductor coils, the first inductor coil and the second inductor coil may be aligned coaxially along a longitudinal axis so that the internal cavity of the coil is aligned along the longitudinal axis.

[0114] In some embodiments, the first inductor coil and the second inductor coil are wound in the same direction. In some embodiments, the second inductor coil is wound in a different direction from the first inductor coil.

[0115] An induction heating array may include any suitable number of inductor coils. A susceptor array includes a plurality of inductor coils. An induction heating array includes at least two inductor coils. Preferably, the number of inductor coils in the induction heating array is equal to the number of susceptors in the susceptor array. The number of inductor coils in the induction heating array may differ from the number of susceptors in the susceptor array. When the number of inductor coils is equal to the number of susceptors, preferably each inductor coil is placed around the susceptor. Particularly preferably, each inductor coil is substantially extended to the length of the susceptor on which it is placed.

[0116] The susceptor array may include a flux concentrator. The flux concentrator may be placed around the inductor coil of the induction heating array. The flux concentrator is configured to distort the variable magnetic field generated by the inductor coil toward the susceptor array.

[0117] Advantageously, by distorting the magnetic field toward the susceptor array, the flux concentrator can concentrate the magnetic field in the susceptor array. This can increase the efficiency of the induction heating array compared to an embodiment in which the flux concentrator is not provided. As used herein, the phrase “concentrate the magnetic field” means to distort the magnetic field such that the magnetic energy density of the magnetic field is increased at the place where the magnetic field is “concentrated.”

[0118] As used herein, the term "flux concentrator" refers to a component having high relative magnetic permeability that acts to concentrate and guide a magnetic field or magnetic field line generated by an inductor coil. As used herein, the term "relative magnetic permeability" refers to the ratio of the magnetic permeability of a material or a medium, such as a flux concentrator, to the magnetic permeability of free space, "μ0," where μ0 is 4πX10 -7 NA -2 am.

[0119] As used herein, the term “high relative magnetic transmittance” refers to a relative magnetic transmittance of at least 5, e.g., at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 80, or at least 100 at 25°C. These exemplary values ​​preferably represent relative magnetic transmittance values ​​for a frequency of 6 to 8 MHz and a temperature of 25°C.

[0120] The flux concentrator may be formed from any suitable material or a combination of materials. Preferably, the flux concentrator comprises any other suitable material, such as a ferromagnetic material, e.g., a ferrite material, ferrite powder contained in a binder, or a ferrite material such as ferrite iron, ferromagnetic steel, or stainless steel.

[0121] In some embodiments, the induction heating array includes a flux concentrator positioned around a first inductor coil and a second inductor coil. In these embodiments, the flux concentrator is configured to distort the variable magnetic field generated by the first inductor coil toward a first portion of the susceptor array and to distort the variable magnetic field generated by the second inductor coil toward a second portion of the susceptor array.

[0122] In some of these embodiments, a portion of the flux concentrator extends into an intermediate element between the first portion of the susceptor array and the second portion of the susceptor array. Extending a portion of the flux concentrator into an intermediate element between the first portion of the susceptor array and the second portion of the susceptor array can further distort the magnetic field generated by the first inductor coil and the magnetic field generated by the second inductor coil. This additional distortion can result in the magnetic field generated by the first inductor coil being further concentrated toward the first portion of the susceptor array and the magnetic field generated by the second inductor coil being further concentrated toward the second portion of the susceptor array. This can further improve the efficiency of the induction heating array.

[0123] In some embodiments, the induction heating array includes a plurality of flux concentrators. In some preferred embodiments, individual flux concentrators are positioned around each inductor coil. Providing a dedicated flux concentrator for each inductor coil allows the flux concentrator to be optimally configured to distort the magnetic field generated by the inductor coil. This arrangement also allows the induction heating array to be formed into modular induction heating units. Each induction heating unit may include an inductor coil and a flux concentrator. Providing modular induction heating units can facilitate the standardized manufacturing of the induction heating array and allows individual units to be removed and replaced.

[0124] In some preferred embodiments, the induction heating array comprises: a first flux concentrator disposed around a first inductor coil, said first flux concentrator configured to distort a variable magnetic field generated by the first inductor coil toward a first portion of the susceptor array; and a second flux concentrator disposed around a second inductor coil, said second flux concentrator configured to distort a variable magnetic field generated by the second inductor coil toward a second portion of the susceptor array.

[0125] In these preferred embodiments, a portion of the first flux concentrator may extend into an intermediate element between the first portion of the susceptor array and the second portion of the susceptor array. In these preferred embodiments, a portion of the second flux concentrator may extend into an intermediate element between the first portion of the susceptor array and the second portion of the susceptor array. Extending a portion of the flux concentrator into an intermediate element between the susceptors enables the flux concentrator to further distort the magnetic field generated by the inductor coil toward the susceptor.

[0126] The induction heating array may further include an induction heating array housing. The housing can accommodate the susceptor array, inductor coil, and flux concentrator together. This can help fix the relative arrangement of the components of the induction heating array and improve coupling between the components. Preferably, the induction heating array housing is formed of an electrically insulating material.

[0127] When an induction heating array comprises individual induction heating units each comprising an inductor coil and a flux concentrator, each induction heating unit may comprise an induction heating unit housing. The induction heating unit housing can hold the components of the induction heating unit together and improve coupling between the components. Preferably, the induction heating unit housing is formed of an electrically insulating material.

[0128] The aerosol generator may include a power supply. The power supply may be any suitable type of power supply. The power supply may be a DC power supply. In some preferred embodiments, the power supply is a battery, such as a rechargeable lithium-ion battery. The power supply may be another form of charge storage device, such as a capacitor. The power supply may require recharging. The power supply may have a capacity that allows for the storage of sufficient energy for one or more uses of the device. For example, the power supply may have a capacity sufficient to continuously generate an aerosol for a period of about 6 minutes, corresponding to the usual time it takes to smoke a regular cigarette, or for a period of several times 6 minutes. In other examples, the power supply may have a capacity sufficient to allow for a predetermined number of device uses or individual activations. In one embodiment, the power supply is a DC power supply having a DC supply voltage in the range of about 2.5 volts to about 4.5 volts and a DC supply current in the range of about 1 ampere to about 10 amperes (corresponding to a DC power supply in the range of about 2.5 watts to about 45 watts).

[0129] The aerosol generator may include a controller connected to an induction heating array and a power supply. In particular, the aerosol generator may include a first inductor coil and a second inductor coil and a controller connected to the power supply. The controller is configured to control the power supply from the power supply to the induction heating array. The controller may include a programmable microprocessor, a microcontroller, or an application-specific integrated chip (ASIC) or other electronic circuit capable of providing control. The controller may include additional electronic components. The controller may be configured to regulate the current supply to the induction heating array. Current may be supplied to the induction heating array continuously following the activation of the aerosol generator, or intermittently, for example, on a per-puff basis.

[0130] Advantageously, the controller may include a DC / AC converter, which may include a Class C, Class D, or Class E power amplifier. The DC / AC converter may be positioned between the power supply and the induction heating array.

[0131] The aerosol generator may further include a DC / DC converter between the power supply unit and the DC / AC converter.

[0132] The aerosol generating device may include a first switch between a power supply and a first inductor coil, and a second switch between a power supply and a second inductor coil. A controller may be configured to turn the first switch on and off at a first switching speed to drive a first alternating pulse width modulation signal within the first inductor coil when the second switch is kept off. A controller may be configured to turn the second switch on and off at a second switching speed to drive a second alternating pulse width modulation signal within the second inductor coil when the first switch is kept off.

[0133] The controller may be configured to supply an alternating pulse width modulation signal to an induction heating array having any suitable frequency. The controller may be configured to supply an alternating pulse width modulation signal to an induction heating array having a frequency of about 5 kHz to about 30 MHz. In some preferred embodiments, the controller is configured to supply an alternating pulse width modulation signal to an induction heating array having a frequency of about 5 kHz to about 500 kHz. In some embodiments, the controller is configured to supply a high frequency alternating pulse width modulation signal to an induction heating array. As used herein, the term “high frequency alternating pulse width modulation signal” means an alternating pulse width modulation signal having a frequency of about 500 kHz to about 30 MHz. The high frequency alternating pulse width modulation signal may have a frequency of about 1 MHz to about 30 MHz, such as about 1 MHz to about 10 MHz, or about 5 MHz to about 8 MHz.

[0134] The aerosol generating device may include a device housing. The device housing may be elongated. The device housing may include any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials comprising one or more of these materials, or thermoplastic resins suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and non-brittle.

[0135] The device housing may include a device cavity for receiving an aerosol-forming material. The device cavity is configured to receive at least a portion of an aerosol-generating article. The device cavity may have any suitable shape and size. The device cavity may be substantially cylindrical. The device cavity may have a substantially circular transverse cross-section.

[0136] The susceptor array may be placed within the device cavity. The susceptor array may be placed around the device cavity. If the susceptor array is a tubular susceptor array, the susceptor array may surround the device cavity. The inner surface of the susceptor array may form the inner surface of the device cavity.

[0137] The first inductor coil and the second inductor coil may be placed within the device cavity. The first inductor coil and the second inductor coil may be placed around the device cavity. The first inductor coil and the second inductor coil may surround the device cavity. The inner surfaces of the first inductor coil and the second inductor coil may form the inner surface of the device cavity.

[0138] The above device may have a proximal end and a distal end opposite to the proximal end. Preferably, the device cavity is arranged at the proximal end of the device.

[0139] The device cavity may have a proximal end and a distal end opposite to the proximal end. The proximal end of the device cavity may be substantially open to receive an aerosol-generating article.

[0140] In some embodiments, the aerosol generating device further includes a cover movable over the proximal end of the device cavity to prevent insertion of an aerosol generating article into the device cavity.

[0141] In some preferred embodiments, a first inductor coil is arranged toward the proximal end of the device cavity, and a second inductor coil is arranged toward the distal end of the device cavity. In these preferred embodiments, a controller may be configured to initiate heating of the aerosol-forming substrate by driving a first variable current in the first inductor coil and subsequently driving a second variable current in the second inductor coil. This operation heats the proximal part of the device cavity before heating the distal part of the device cavity.

[0142] The device housing includes an air inlet. The air inlet may be configured to allow ambient air to enter the device housing. The device housing may include any appropriate number of air inlets. The device housing may include a plurality of air inlets.

[0143] The device housing may include an air outlet. The air outlet may be configured to allow air to enter the device cavity from inside the device housing. The device housing may include any suitable number of air outlets. The device housing may include a plurality of air outlets.

[0144] If the intermediate element of the susceptor array is gas permeable, the aerosol generator can define an airflow path extending from the air inlet to the intermediate element of the susceptor array. This airflow path allows air to be drawn from the air inlet through the intermediate element into the device cavity through the aerosol generator.

[0145] In some embodiments, the device cavity comprises a proximal end and a distal end opposite to the proximal end. In these embodiments, the device cavity may be open at the proximal end to accommodate an aerosol generating article. In these embodiments, the device cavity may be substantially closed at the distal end. The device housing may include an air outlet at the distal end of the device cavity. The aerosol generating device may further include an annular seal toward the proximal end of the device cavity. The annular seal may extend into the device cavity. The annular seal may provide a substantially hermetic seal between the device housing and the outer surface of the aerosol generating article accommodated within the device cavity. This may, in use, reduce the volume of air drawn into the device cavity through any gap existing between the outer surface of the aerosol generating article and the inner surface of the device cavity. This may increase the volume of air drawn into the aerosol generating article through a permeable intermediate element.

[0146] In some embodiments, the device housing includes a mouthpiece. The mouthpiece may include at least one air inlet and at least one air outlet. The mouthpiece may include more than one air inlet. One or more of the air inlets may reduce the temperature of the aerosol before the aerosol is delivered to the user and may reduce the concentration of the aerosol before the aerosol is delivered to the user.

[0147] In some embodiments, a mouthpiece may be provided as part of an aerosol generating article. As used herein, the term “mouthpiece” refers to a part of an aerosol generating system that is placed in the user’s mouth to directly inhale an aerosol generated by the aerosol generating system from an aerosol generating article received by an aerosol generating device.

[0148] In some embodiments, the controller may be configured to monitor the current supplied to the induction heating array. The controller may be configured to determine the temperature of the susceptor array based on the monitored current. The controller may be configured to monitor a first variable current and determine the temperature of a first portion of the susceptor array based on the monitored first variable current. The controller may be configured to monitor a second variable current and determine the temperature of a second portion of the susceptor array based on the monitored second variable current.

[0149] The aerosol generator may include a temperature sensor. The temperature sensor may be arranged to detect the temperature of the susceptor array. A controller may be configured to control a first variable current based on the temperature of the susceptor array detected by the temperature sensor. A controller may be configured to control a second variable current based on the temperature of the susceptor array detected by the temperature sensor.

[0150] The temperature sensor can be any suitable type of temperature sensor. For example, the temperature sensor can be a thermocouple, a negative temperature coefficient resistance temperature sensor, or a positive temperature coefficient resistance temperature sensor.

[0151] In some preferred embodiments, the aerosol generator may include a first temperature sensor arranged to detect the temperature of a first portion of the susceptor array. In these embodiments, the controller may be configured to control a first variable current based on the temperature of the first portion of the susceptor array detected by the first temperature sensor.

[0152] In some preferred embodiments, the aerosol generator may include a second temperature sensor arranged to detect the temperature of a second portion of the susceptor array. In these embodiments, the controller may be configured to control a second variable current based on the temperature of the second portion of the susceptor array detected by the second temperature sensor.

[0153] The aerosol generating device may include a user interface for activating the device, for example, a button for initiating heating of an aerosol generating article.

[0154] The aerosol generating device may include a display for indicating the state of the device or the aerosol forming substrate.

[0155] An aerosol generating device may include a detector for detecting the presence of an aerosol-forming substrate. If the aerosol generating device includes a device cavity for receiving an aerosol-forming substrate, the aerosol generating device may include a detector for detecting the presence of the aerosol-forming substrate within the device cavity. If the aerosol generating device is configured to receive at least a portion of an aerosol-generating article, the aerosol generating device may include an aerosol-generating article detector configured to detect the presence of the aerosol-generating article within the device cavity.

[0156] When the aerosol-forming material detector detects the presence of the aerosol-forming material, the controller may be configured to start heating by driving a first variable current within the first inductor coil.

[0157] When the aerosol generating item detector detects the presence of an aerosol generating item within the device cavity, the controller may be configured to initiate heating by driving a first variable current within the first inductor coil.

[0158] The aerosol-forming material detector and the aerosol-generating article detector may include any suitable type of detector. For example, the detector may be an optical, acoustic, capacitive, or inductive detector.

[0159] An aerosol generating device may include a puff detector configured to detect when a user puffs on an aerosol generating system. As used herein, the term "puff" is used to indicate that a user inhales the aerosol generating system to receive an aerosol.

[0160] Preferably, the aerosol generator is portable. The aerosol generator may have a size similar to a conventional cigar or cigarette. The aerosol generator may have a total length of about 30 mm to about 150 mm. The aerosol generator may have an outer diameter of about 5 mm to about 30 mm.

[0161] An aerosol generator may also form part of an aerosol generation system.

[0162] The aerosol generating system may further include an aerosol generating article. The aerosol generating article may include an aerosol forming substrate. The aerosol generating article may include a first aerosol forming substrate; and a second aerosol forming substrate. When the aerosol generating article is received within the device cavity, at least a portion of the first aerosol forming substrate may be received in a first portion of the device cavity, and at least a portion of the second aerosol forming substrate may be received in a second portion of the device cavity.

[0163] A susceptor array forming part of the induction heating array of an aerosol generator is configured to heat an aerosol-forming substrate.

[0164] The aerosol-forming substrate may contain nicotine. The nicotine-containing aerosol-forming substrate may be a nicotine salt matrix.

[0165] The aerosol-forming substrate may be a liquid. The aerosol-forming substrate may include a solid component and a liquid component. Preferably, the aerosol-forming substrate may be a solid.

[0166] The aerosol-forming substrate may include a plant-based material. The aerosol-forming substrate may include tobacco. The aerosol-forming substrate may include a tobacco-containing material containing volatile tobacco flavor compounds that are released from the aerosol-forming substrate upon heating. The aerosol-forming substrate may include a non-tobacco material. The aerosol-forming substrate may include a homogenized plant-based material. The aerosol-forming substrate may include a homogenized tobacco material. The homogenized tobacco material may be formed by aggregating fine tobacco particles. In a particularly preferred embodiment, the aerosol-forming substrate comprises a crimped sheet of homogenized tobacco material. As used herein, the term 'crimped sheet' refers to a sheet having a plurality of substantially parallel ridges or wavy folds.

[0167] The aerosol-forming substrate may comprise at least one aerosol-forming agent. The aerosol-forming agent is any suitable known compound or mixture of compounds that facilitates the formation of a dense and stable aerosol upon use and is substantially resistant to thermal sensitivity at the operating temperature of the system. Suitable aerosol-forming agents are well known in the art and include, but are not limited to, polyhydric alcohols such as triethylene glycol, 1,3-butanediol, and glycerin; esters of polyhydric alcohols such as glycerol mono-, di-, or triacetate; and aliphatic esters of mono-, di-, or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. Preferred aerosol-forming agents may comprise polyhydric alcohols or mixtures thereof, such as triethylene glycol and 1,3-butanediol. Preferably, the aerosol-forming agent is glycerin. The homogenized tobacco material may have an aerosol-forming agent content of 5% by weight or more based on dry weight, such as 5% by weight to 30% by weight, where present. The aerosol-forming material may include other additives and components, such as flavoring agents.

[0168] An aerosol-forming substrate may be included within the aerosol-generating article. An aerosol-generating device comprising an induction heating array may be configured to accommodate at least a portion of the aerosol-generating article. The aerosol-generating article may have any suitable shape. The aerosol-generating article may be substantially cylindrical in shape. The aerosol-generating article may be substantially elongated. The aerosol-generating article may have a length and a circumference substantially perpendicular to this length.

[0169] An aerosol-forming substrate may be provided as an aerosol-forming site containing an aerosol-forming substrate. The aerosol-generating site may include a plurality of aerosol-forming substrates. The aerosol-generating site may include a first aerosol-forming substrate and a second aerosol-forming substrate. In some embodiments, the second aerosol-forming substrate is substantially identical to the first aerosol-forming substrate. In some embodiments, the second aerosol-forming substrate is different from the first aerosol-forming substrate.

[0170] If the aerosol generating site includes multiple aerosol-forming materials, the number of aerosol-forming materials may be equal to the number of susceptors in the susceptor array. Similarly, the number of aerosol-forming materials may be equal to the number of inductor coils in the induction heating array.

[0171] The aerosol generating site may be substantially cylindrical in shape. The aerosol generating site may be substantially elongated. The aerosol generating site may also have a length and a circumference substantially perpendicular to that length.

[0172] When the aerosol generating site comprises a plurality of aerosol-forming substrates, the aerosol-forming substrates may be arranged from one end to the other along the axis of the aerosol generating site. In some embodiments, the aerosol generating site may include a separator between adjacent aerosol-forming substrates.

[0173] In some preferred embodiments, the aerosol generating article may have a total length of 30 mm and 100 mm. In some embodiments, the aerosol generating article has a total length of approximately 45 mm. The aerosol generating article may have an outer diameter of approximately 5 mm to approximately 12 mm. In some embodiments, the aerosol generating article may have an outer diameter of approximately 7.2 mm.

[0174] The aerosol generating area may have a length of about 7 mm to about 15 mm. In some embodiments, the aerosol generating area may have a length of about 10 mm or 12 mm.

[0175] The aerosol generating portion preferably has an outer diameter approximately equal to the outer diameter of the aerosol generating article. The outer diameter of the aerosol forming substrate may be about 5 mm to about 12 mm. In one embodiment, the aerosol generating portion may have an outer diameter of about 7.2 mm.

[0176] The aerosol generating article may include a filter plug. The filter plug may be located at the proximal end of the aerosol generating article. The filter plug may be a cellulose acetate filter plug. In some embodiments, the filter plug may have a length of about 5 mm to about 10 mm. In some preferred embodiments, the filter plug may have a length of about 7 mm.

[0177] A first portion of the susceptor array may be arranged to heat a first portion of the aerosol-forming substrate. A first portion of the susceptor array may be arranged to substantially surround a first portion of the aerosol-forming substrate. A second portion of the susceptor array may be arranged to heat a second portion of the aerosol-forming substrate. A second portion of the susceptor array may be arranged to substantially surround a second portion of the aerosol-forming substrate.

[0178] The aerosol generating article may include an outer wrapper. The outer wrapper may be formed of paper. The outer wrapper may be gas permeable at the aerosol generating site. In particular, in an embodiment comprising a plurality of aerosol generating substrates, the outer wrapper may include perforations or other air inlets at the interface between adjacent aerosol generating substrates. If a separation portion is provided between adjacent aerosol generating substrates, the outer wrapper may include perforations or other air inlets upon separation. This may allow the aerosol generating substrate to directly provide air that is not drawn in through other aerosol generating substrates. This may increase the amount of air received by each aerosol generating substrate. This improves the characteristics of the aerosol generated from the aerosol generating substrate.

[0179] Additionally, the aerosol generating article may include a separator between the aerosol forming substrate and the filter plug. The separator may be approximately 18 mm, but may be in the range of approximately 5 mm to approximately 25 mm.

[0180] In addition, it should be understood that specific combinations of the various features mentioned above may be implemented, supplied, or used independently. Brief explanation of the drawing

[0181] Embodiments of the present disclosure will now be described by way of example with reference to the accompanying drawings: FIG. 1 shows a schematic diagram of a susceptor array according to an embodiment of the present disclosure arranged between a pair of inductor coils; FIG. 2 shows a schematic diagram of a susceptor array according to an embodiment of the present disclosure arranged between a pair of inductor coils; FIG. 3 shows an exploded perspective view of a susceptor array according to an embodiment of the present disclosure; FIG. 4 shows a perspective view of the susceptor array of FIG. 3; FIG. 5 shows a cross-sectional view of an aerosol generating system according to an embodiment of the present disclosure, wherein the aerosol generating system comprises an aerosol generating article and an aerosol generating device having an induction heating array; FIG. 6 shows a cross-sectional view of the proximal end of the aerosol generator of FIG. 5; FIG. 7 shows a cross-sectional view of the aerosol generating system of FIG. 5, wherein an aerosol generating article is housed in an aerosol generating device; FIG. 8 shows a schematic diagram of a susceptor array according to an embodiment of the present disclosure arranged between a pair of inductor coils; FIG. 9 shows a cross-sectional view of an aerosol generating system according to another embodiment of the present disclosure, wherein the aerosol generating system comprises an aerosol generating article and an aerosol generating device having an induction heating array; Figure 10 shows a temperature graph over time for the susceptor array of Figure 8; FIG. 11 shows an exemplary circuit of an induction heating array; FIG. 12 shows an exemplary circuit for controlling an induction heating array; Figure 13 shows a diagram of a pulse width modulation signal for driving an induction heating array. Specific details for implementing the invention

[0182] FIG. 1 shows a schematic diagram of a susceptor array (10) according to an embodiment of the present disclosure. The susceptor array (10) is an elongated tubular element having a circular cross section. The susceptor array (10) includes a first susceptor (12), a second susceptor (14), and a separation portion (15) between the first susceptor (12) and the second susceptor (14). The first susceptor (12) and the second susceptor (14) are each elongated tubular elements having a circular cross section. The first susceptor (12) and the second susceptor (14) are end-to-end coaxially aligned along the longitudinal axis AA.

[0183] The susceptor array (10) includes a cylindrical cavity (20) open at both ends, defined by the inner surfaces of the first susceptor (12) and the second susceptor (14). The cavity (20) is configured to accommodate a portion of a cylindrical aerosol generating article (not shown) containing an aerosol forming substrate, so that the outer surface of the aerosol generating article can be heated by the first susceptor and the second susceptor, thereby heating the aerosol forming substrate.

[0184] The cavity (20) comprises three parts: a first part (22) at a first end defined by the inner surface of a tubular first susceptor (12), a second part (24) at a second end opposite to the first end defined by the inner surface of a tubular second susceptor (14), and an intermediate part (26) bordered by a separation part (15) between the first susceptor (12) and the second susceptor (14). The first susceptor (12) is arranged to heat a first part of an aerosol generating article received in the first part (22) of the cavity (20), and the second susceptor (14) is arranged to heat a second part of an aerosol generating article received in the second part (24) of the cavity (20).

[0185] The first inductor coil (32) is positioned around the first susceptor (12), and the length of the first susceptor (12) is substantially extended. Thus, the first susceptor (12) is surrounded by the first inductor coil (32) substantially along its length. When a variable current, preferably an AC current, is supplied to the first inductor coil (32), the first inductor coil (32) generates a variable magnetic field that is concentrated in the first part (22) of the cavity (20). This variable magnetic field generated by the first inductor coil (32) induces eddy currents within the first susceptor (12), causing the first susceptor (12) to heat up.

[0186] A second inductor coil (34) is positioned around the second susceptor (14), and the length of the second susceptor (14) is substantially extended. Thus, the second susceptor (14) is surrounded by the second inductor coil (34) along substantially its length. When a variable current, preferably an AC current, is supplied to the second inductor coil (34), the second inductor coil (34) generates a variable magnetic field that is concentrated in the second part (24) of the cavity (20). This variable magnetic field generated by the second inductor coil (34) induces eddy currents within the second susceptor (14), causing the second susceptor (14) to heat up.

[0187] The separation portion (15) between the first susceptor (12) and the second susceptor (14) provides a space between the first susceptor (12) and the second susceptor (14), and the first susceptor is not heated by induction when exposed to a variable magnetic field generated by the first inductor coil (32) or the second inductor coil (34). Additionally, the separation portion (15) thermally insulates the second susceptor (14) from the first susceptor (12), so that the rate of heat transfer between the first susceptor (12) and the second susceptor (14) is reduced compared to susceptor elements in which the first susceptor and the second susceptor are arranged adjacent to each other in direct thermal contact. As a result, by providing a separation portion (15) between the first susceptor (12) and the second susceptor (14), selective heating of the first portion (22) of the cavity (20) by the first susceptor (12) is made possible by minimal heating of the second portion (22) of the cavity (20), and selective heating of the second portion (24) of the cavity (20) by the second susceptor (14) is made possible by minimal heating of the first portion (22) of the cavity (20).

[0188] The first susceptor (12) and the second susceptor (14) may be heated simultaneously by simultaneously supplying a variable current, preferably an AC current, to the first inductor coil (32) and the second inductor coil (34). Alternatively, the first susceptor (12) and the second susceptor (14) may be heated independently or alternately by supplying a variable current, preferably an AC current, to the first inductor coil (32) without supplying current to the second inductor coil (34), and subsequently supplying a variable current, preferably an AC current, to the second inductor coil (34) without supplying current to the first inductor coil (32). Additionally, it is expected that a variable current, preferably an AC current, may be supplied sequentially to the first inductor coil (32) and the second inductor coil (34).

[0189] FIG. 2 shows a schematic diagram of a susceptor array according to another embodiment of the present disclosure. The susceptor array shown in FIG. 2 is substantially the same as the susceptor array shown in FIG. 1, and the same reference numerals are used to describe similar features.

[0190] The susceptor array (10) of FIG. 2 is an elongated tubular element having a circular cross-section. The susceptor array (10) includes a first susceptor (12) and a second susceptor (14). The difference between the susceptor array (10) of FIG. 1 and the susceptor array (10) of FIG. 2 is that the susceptor array (10) of FIG. 2 includes an intermediate element (16) positioned between the first susceptor (12) and the second susceptor (14). In the embodiment of FIG. 2, there is still a separation between the first susceptor (12) and the second susceptor (14), but the separation is filled by the intermediate element (16). In this embodiment, the intermediate element (16) is fixed to the end of the first susceptor (12) and also fixed to the end of the second susceptor (14). Fixing the intermediate element (16) to the end of the first susceptor (12) and fixing the intermediate element (16) to the end of the second susceptor (14) indirectly connects the first susceptor (12) to the second susceptor (14). Advantageously, fixing the first susceptor (12) indirectly to the second susceptor (14) allows the susceptor array to form an integral structure.

[0191] The intermediate element (16) comprises a thermal insulating material. The thermal insulating material is also electrically insulating. In this embodiment, the intermediate element (16) is formed from a polymer material such as PEEK. Thus, the intermediate element (16) between the first susceptor (12) and the second susceptor (14) provides space between the first susceptor (12) and the second susceptor (14), and the first susceptor is not heated by induction when exposed to a variable magnetic field generated by the first inductor coil (32) or the second inductor coil (34). Additionally, the intermediate element (16) thermally insulates the second susceptor (14) from the first susceptor (12), so that the rate of heat transfer between the first susceptor (12) and the second susceptor (14) is reduced compared to a susceptor arrangement in which the first susceptor and the second susceptor are arranged adjacent to each other in direct thermal contact. The intermediate element (16) can also further reduce the heat transfer rate between the first susceptor (12) and the second susceptor (14) compared to the separation portion (15) of the susceptor array (10) of FIG. 1. Consequently, providing the intermediate element (16) between the first susceptor (12) and the second susceptor (14) enables selective heating of the first portion (22) of the cavity (20) by the first susceptor (12) with minimal heating of the second portion (24) of the cavity (20), and enables selective heating of the second portion (24) of the cavity (20) by the second susceptor (14) with minimal heating of the first portion (22) of the cavity (20).

[0192] FIGS. 3 to 7 show schematic diagrams of an aerosol generating system according to an embodiment of the present disclosure. The aerosol generating system includes an aerosol generating device (100) and an aerosol generating article (200). The aerosol generating device (100) includes an induction heating array (110) according to the present disclosure. The induction heating array (110) includes a susceptor array (120) according to the present disclosure.

[0193] FIGS. 3 and 4 show a schematic diagram of a susceptor array (120). The susceptor array (120) includes: a first susceptor (122), a second susceptor (124), a third susceptor (126), a first intermediate element (128), and a second intermediate element (130). The first intermediate element (128) is positioned between the first susceptor (122) and the second susceptor (124). The second intermediate element (130) is positioned between the second susceptor (124) and the third susceptor 126.

[0194] In the present embodiment, the first susceptor (122), the second susceptor (124), and the third susceptor (126) are each identical. Each susceptor (122, 124, 126) is an elongated tubular susceptor defining an internal cavity. Each susceptor and its corresponding internal cavity are substantially cylindrical, having a constant circular cross-section along the length of the susceptor. The internal cavity of the first susceptor (122) defines a first region (134). The internal cavity of the second susceptor (124) defines a second region (136). The internal cavity of the third susceptor defines a third region (138).

[0195] Similarly, the first intermediate element (128) and the second intermediate element (130) are identical. The intermediate elements (128, 130) are tubular, defining an internal cavity. Each intermediate element (128, 130) is substantially cylindrical and has a constant circular cross-section along the length of the intermediate element. The outer diameter of the intermediate elements (128, 130) is the same as the outer diameter of the susceptor (122, 124, 126), so that the outer surface of the intermediate elements (128, 130) can be aligned coplanarly with the outer surface of the susceptor (122, 124, 126). The inner diameter of the intermediate element (128, 130) is also the same as the inner diameter of the susceptor (122, 124, 126), so that the inner surface of the intermediate element (128, 138) can be aligned coplanarly with the inner surface of the susceptor (122, 124, 126).

[0196] The first susceptor (122), the first intermediate element (128), the second susceptor (124), the second intermediate element (130), and the third susceptor (126) are arranged end-to-end and are aligned coaxially on the axis BB. In this arrangement, the susceptors (122, 124, 126) and the intermediate elements (128, 130) form a tubular, elongated cylindrical structure. This structure forms a susceptor array (120) according to an embodiment of the present disclosure.

[0197] The elongated tubular susceptor array (120) includes an internal cavity (140). The susceptor array cavity (140) is defined by the internal cavity of the susceptors (122, 124, 126) and the internal cavity of the intermediate elements (128, 130). The susceptor array cavity (140) is configured to accommodate an aerosol generating portion of an aerosol generating article (200), as described in more detail below.

[0198] The intermediate elements (128, 130) are formed of an electrically insulating and thermally insulating material. As such, the susceptors (122, 124, 126) are substantially electrically and thermally insulated from one another. The material of the intermediate elements (128, 130) is also substantially impermeable to gases. In this embodiment, the tubular susceptor array (120) is substantially impermeable to gases from the outer surface to the inner surface defining the susceptor array cavity (140).

[0199] FIGS. 5, FIGS. 6 and FIGS. 7 show schematic cross-sectional views of an aerosol generating device (100) and an aerosol generating article (200).

[0200] The aerosol generating device (100) comprises a substantially cylindrical device housing (102) having a shape and size similar to a conventional cigar. The device housing (102) defines a device cavity (104) at a proximal end. The device cavity (104) is substantially cylindrical, open at the proximal end and substantially closed at the distal end opposite the proximal end. The device cavity (104) is configured to accommodate an aerosol generating portion (210) of an aerosol generating article (200). Thus, the length and diameter of the device cavity (104) are substantially similar to the length and diameter of the aerosol generating portion (210) of the aerosol generating article (200).

[0201] The aerosol generator (100) further comprises a power supply (106) in the form of a rechargeable nickel-cadmium battery, a controller (108) in the form of a printed circuit board containing a microprocessor, an electrical connector (109), and an induction heating array (110). The power supply (106), the controller (108), and the induction heating array (110) are all housed within a device housing (102). The induction heating array (110) of the aerosol generator (100) is arranged at the proximal end of the device (100) and is generally positioned around the device cavity (104). The electrical connector (109) is arranged at the distal end of the device housing (109) facing the device cavity (104).

[0202] The controller (108) is configured to control the power supply from the power supply unit (106) to the induction heating array (110). The controller (108) further includes a DC / AC converter including a D-grade power amplifier and is configured to supply a variable current, preferably an AC current, to the induction heating array (110). Additionally, or alternatively, the DC / AC inverter may include at least one of a C-grade and an E-grade power amplifier. The controller (108) is also configured to control the recharging of the power supply unit (106) from the electrical connector (109). Additionally, the controller (108) includes a puff sensor (not shown) configured to detect when a user inhales an aerosol generating item contained within the device cavity (104).

[0203] The induction heating array (110) comprises three induction heating units, including a first induction heating unit (112), a second induction heating unit (114), and a third induction heating unit (116). The first induction heating unit (112), the second induction heating unit (114), and the third induction heating unit (116) are substantially identical.

[0204] The first induction heating unit (112) includes a cylindrical, tubular first inductor coil (150), a cylindrical, tubular first flux concentrator (152) disposed around the first inductor coil (150), and a cylindrical, tubular first inductor unit housing (154) disposed around the first flux concentrator (152).

[0205] The second induction heating unit (114) includes a cylindrical, tubular second inductor coil (160), a cylindrical, tubular second flux concentrator (162) disposed around the second inductor coil (160), and a cylindrical, tubular second inductor unit housing (164) disposed around the second flux concentrator (162).

[0206] The third induction heating unit (116) includes a cylindrical, tubular third inductor coil (170), a cylindrical, tubular third flux concentrator (172) disposed around the third inductor coil (170), and a cylindrical, tubular third inductor unit housing (174) disposed around the third flux concentrator (172).

[0207] Accordingly, each induction heating unit (112, 114, 116) forms a substantially tubular unit having a circular cross-section. In each induction heating unit (112, 114, 116), a flux concentrator extends over the proximal and distal ends of an inductor coil so that the inductor coil is arranged within the annular cavity of the flux concentrator. Similarly, each induction heating unit housing extends over the proximal and distal ends of a flux concentrator so that the flux concentrator and the inductor coil are arranged within the annular cavity of the induction heating unit housing. This arrangement allows the flux concentrator to concentrate the magnetic field generated by the inductor coil within the inner cavity of the inductor coil. This arrangement also allows the inductor unit housing to contain the flux concentrator and the inductor coil within the inductor unit housing.

[0208] The induction heating array (110) further includes a susceptor array (120). The susceptor array (120) is positioned around the inner surface of the device cavity (104). In this embodiment, the device housing (102) defines the inner surface of the device cavity (104). However, in some embodiments, the inner surface of the device cavity is expected to be defined by the inner surface of the susceptor array (120).

[0209] Induction heating units (112, 114, 116) are positioned around the susceptor array (120) so that the susceptor array (120) and the induction heating units (112, 114, 116) are arranged concentrically around the device cavity (104). A first induction heating unit (112) is positioned around a first susceptor (122) at the distal end of the device cavity (104). A second induction heating unit (114) is positioned around a second susceptor (124) at the central part of the device cavity (104). A third induction heating unit (116) is positioned around a third susceptor (126) at the proximal end of the device cavity (104). In some embodiments, it is considered that a flux concentrator may extend into an intermediate element of the susceptor array to further distort the magnetic field generated by the inductor coil toward the susceptor.

[0210] The first inductor coil (150) is connected to a controller (108) and a power supply unit (106), and the controller (108) is configured to supply a variable current, preferably an AC current, to the first inductor coil (150). When the variable current, preferably an AC current, is supplied to the first inductor coil (150), the first inductor coil (150) generates a variable magnetic field, which heats the first susceptor (122) by induction.

[0211] The second inductor coil (160) is connected to a controller (108) and a power supply unit (106), and the controller (108) is configured to supply a variable current, preferably an AC current, to the second inductor coil (160). When the variable current, preferably an AC current, is supplied to the second inductor coil (160), the second inductor coil (160) generates a variable magnetic field, which heats the second susceptor (124) by induction.

[0212] The first inductor coil (170) is connected to a controller (108) and a power supply unit (106), and the controller (108) is configured to supply a variable current, preferably an AC current, to the third inductor coil (170). When the variable current, preferably an AC current, is supplied to the third inductor coil (170), the third inductor coil (170) generates a variable magnetic field, which heats the third susceptor (126) by induction.

[0213] The device housing (102) also defines an air inlet (180) near the distal end of the device cavity (106). The air inlet (180) is configured so that ambient air can be drawn into the device housing (102). An airflow path (181) is defined through the device between the air inlet (180) and the air outlet within the distal end of the device cavity (104), allowing air to be drawn from the air inlet (180) into the device cavity (104).

[0214] The aerosol generating article (200) is generally in the form of a cylindrical rod having a diameter similar to the inner diameter of the device cavity (104). The aerosol generating article (200) comprises a cylindrical aerosol generating portion (210) wrapped together by a cylindrical cellulose acetate filter plug (204) and an outer wrapper (220) of cigarette paper.

[0215] A filter plug (204) is arranged at the proximal end of an aerosol generating article (200) and forms a mouthpiece of an aerosol generating system that allows a user to inhale aerosol generated by the system.

[0216] The aerosol generating portion (210) is arranged at the distal end of the aerosol generating article (200) and has a length substantially equal to the length of the device cavity (104). The aerosol generating portion (210) comprises a plurality of aerosol generating materials, including: a first aerosol generating material (212) at the distal end of the aerosol generating article (200), a second aerosol generating material (214) adjacent to the first aerosol generating material (212), and a third aerosol generating material (216) at the proximal end of the aerosol generating portion (210) adjacent to the second aerosol generating material (216). In some embodiments, it will be understood that two or more aerosol generating materials may be formed of the same material. However, in this embodiment, each aerosol generating material (212, 214, 216) is different. The first aerosol-forming substrate (212) comprises a corrugated sheet of homogenized tobacco material without additional flavoring agents. The second aerosol-forming substrate (214) comprises a corrugated sheet of homogenized tobacco material containing a flavoring agent in the form of menthol. The third aerosol-forming substrate contains a flavoring agent in the form of menthol and does not contain tobacco material or any other nicotine source. Each of the aerosol-forming substrates (212, 214, 216) also comprises one or more aerosol-forming agents and additional components such as water, so that the aerosol-forming substrate is heated to produce an aerosol having desirable sensory characteristics.

[0217] The proximal end of the first aerosol-forming substrate (212) is exposed because it is not covered by the outer wrapper (220). In this embodiment, air can be drawn into the aerosol generating site (210) through the proximal end of the first aerosol-forming substrate (212) at the proximal end of the article (200).

[0218] In this embodiment, the first aerosol-forming substrate (212), the second aerosol-forming substrate (214), and the third aerosol-forming substrate (216) are arranged end-to-end. However, in other embodiments, it is expected that a separation portion may be provided between the first aerosol-forming substrate and the second aerosol-forming substrate, and a separation portion may be provided between the second aerosol-forming substrate and the third aerosol-forming substrate.

[0219] As illustrated in FIG. 7, when the aerosol generating portion (210) of the aerosol generating article (200) is received within the device cavity (104), the length of the first aerosol generating material (212) is such that the first aerosol generating material (212) extends from the distal end of the device cavity (104) through the first region (134) of the first susceptor (122) to the first intermediate member (128). The length of the second aerosol generating material (214) is such that the second aerosol generating material (214) extends from the first intermediate member (128) through the second region (136) of the second susceptor (124) to the second intermediate member (130). The length of the third aerosol-forming material (216) is such that the third aerosol-forming material (216) extends from the second intermediate member (130) to the proximal end of the device cavity (104).

[0220] When in use, when the aerosol generating item (200) is received within the device cavity (104), the user can inhale the aerosol generated by the aerosol generating system by inhaling the proximal end of the aerosol generating item (200). When the user inhales the proximal end of the aerosol generating item (200), air is drawn into the device housing (102) from the air inlet (180) and into the device cavity (104) along the airflow path (181). Air is drawn into the aerosol generating item (200) from the proximal end of the first aerosol forming material (212) through the outlet within the distal end of the device cavity (104).

[0221] In this embodiment, the controller (108) of the aerosol generator (100) is configured to supply power to the inductor coils of the induction heating array (110) in a predetermined sequence. The predetermined sequence includes the step of supplying a variable current, preferably an AC current, to the first inductor coil (150) during a first suction from a user; the step of supplying a variable current, preferably an AC current, to the second inductor coil (160) during a second suction from a user after the first suction is finished; and the step of supplying a variable current, preferably an AC current, to the third inductor coil (170) during a third suction from a user after the second suction is finished. In the fourth suction, the sequence starts again from the first inductor coil (150). This sequence results in the heating of the first aerosol-forming substrate (212) on the first puff, the heating of the second aerosol-forming substrate (214) on the second puff, and the heating of the third aerosol-forming substrate (216) on the third puff. Since the aerosol-forming substrates (212, 214, 216) of the article (100) are all different, this sequence results in a different experience for the user of each puff of the aerosol-generating system.

[0222] The controller (108) will understand that it may be configured to supply power to the inductor coils in different order or simultaneously, depending on the aerosol delivery desired by the user. In some embodiments, the aerosol generator may be controlled by the user to change the order.

[0223] FIG. 8 shows a schematic diagram of a susceptor array (310) according to an embodiment of the present disclosure. The susceptor array (310) is an elongated tubular element having a circular cross section. The susceptor array (310) comprises a single elongated susceptor having a first part (312) and a second part (314). The first part (312) and the second part (314) are each elongated tubular elements having a circular cross section. The first part (312) and the second part (314) are coaxially aligned end-to-end along the longitudinal axis AA.

[0224] The susceptor array (310) includes a cylindrical cavity (320) open at both ends, defined by the inner surfaces of the first portion (312) and the second portion (314). The cavity (320) is configured to accommodate a portion of a cylindrical aerosol generating article (not shown) containing an aerosol forming substrate so that the outer surface of the aerosol generating article can be heated by the first susceptor and the second susceptor, thereby heating the aerosol forming substrate.

[0225] The cavity (320) is configured to accommodate a portion of an aerosol generating article including an aerosol forming material.

[0226] The cavity (320) comprises two parts: a first part (322) at a first end defined by the inner surface of a first part (312) of the susceptor array (310), and a second part (324) at a second end opposite to the first end defined by the inner surface of a second part (314) of the susceptor array (310). The first part (312) of the susceptor array (310) is arranged to heat a first part of an aerosol generating article received in the first part (322) of the cavity (320), and the second part (314) of the susceptor array (310) is arranged to heat a second part of an aerosol generating article received in the second part (324) of the cavity (320).

[0227] The first inductor coil (332) is positioned around the first part (312) of the susceptor array (310) and extends substantially along the length of the first part (312) of the susceptor array (310). Thus, the first part (312) of the susceptor array (310) is surrounded by the first inductor coil (332) substantially along its length. When a variable current, preferably an AC current, is supplied to the first inductor coil (332), the first inductor coil (332) generates a variable magnetic field that is concentrated in the first part (322) of the cavity (320). This variable magnetic field generated by the first inductor coil (332) induces eddy currents in the first part (312) of the susceptor array (310), causing the first part (312) of the susceptor array (310) to heat up.

[0228] The second inductor coil (334) is positioned around the second part (314) of the susceptor array (310) and extends substantially along the length of the second part (314) of the susceptor array (310). Thus, the second part (314) of the susceptor array (310) is surrounded substantially along its length by the second inductor coil (334) of the susceptor array (310). When a variable current, preferably an AC current, is supplied to the second inductor coil (334), the second inductor coil (334) generates a variable magnetic field that is concentrated in the second part (324) of the cavity (320). This variable magnetic field generated by the second inductor coil (334) induces eddy currents within the second part (314) of the susceptor array (310), causing the second susceptor (314) to heat up.

[0229] The first part (312) of the susceptor array (310) and the second part (314) of the susceptor array (310) can be heated simultaneously by simultaneously supplying a variable current, preferably an AC current, to the first inductor coil (332) and the second inductor coil (334). Alternatively, the first part (312) of the susceptor array (310) and the second part (314) of the susceptor array (310) can be heated independently or alternately by supplying a variable current, preferably an AC current, to the first inductor coil (332) without supplying current to the second inductor coil (334), and subsequently supplying a variable current, preferably an AC current, to the second inductor coil (334) without supplying current to the first inductor coil (332). In addition, it is expected that a variable current, preferably an AC current, can be supplied sequentially to the first inductor coil (332) and the second inductor coil (334).

[0230] Temperature sensors in the form of thermocouples are also provided on the outer surface of the susceptor array (310). A first thermocouple (342) is provided on the outer surface of a first part (312) of the susceptor array (310) to detect the temperature of the first part (312) of the susceptor array (310). A second thermocouple (344) is provided on the outer surface of a second part (314) of the susceptor array (310) to detect the temperature of the second part (314) of the susceptor array (310).

[0231] FIG. 9 shows a cross-sectional view of an aerosol generating system (600) according to another embodiment of the present disclosure. The aerosol generating system (600) includes an aerosol generating device (602) comprising a susceptor array (310) of FIG. 8, a first inductor coil (332), and a second inductor coil (334). The aerosol generating device (602) is similar to the aerosol generating device (100) of FIG. 5, and the same reference numerals are used to indicate the same parts.

[0232] The aerosol generating system (600) also includes an aerosol generating article (700). The aerosol generating article (700) includes an aerosol forming substrate (702) in the form of a cylindrical rod and includes a tobacco strand made of homogenized tobacco and an aerosol forming agent. The cylindrical rod of the aerosol forming substrate (702) has a length substantially equal to the length of the device cavity (104). The aerosol generating article (700) also includes a tubular cooling portion (704), a filter portion (706), and a mouse end portion (708). The aerosol forming substrate (702), the tubular cooling portion (704), the filter portion (706), and the mouse end portion (708) are held together by an external wrapper (710).

[0233] In one embodiment, the aerosol generating substrate (702) has a length of 34 mm to 50 mm, more preferably the aerosol generating substrate (702) has a length of 38 mm to 46 mm, and even more preferably the aerosol generating substrate (702) has a length of 42 mm.

[0234] In one embodiment, the total length of the article (700) is 71 mm to 95 mm, more preferably the total length of the article (700) is 79 mm to 87 mm, and even more preferably the total length of the article (700) is 83 mm.

[0235] In one embodiment, the cooling section (704) is an annular tube and defines an air gap within the cooling section (704). The air gap provides a chamber for the heated volatile components generated from the aerosol-forming substrate (702) to flow through. The cooling section (704) is hollow to provide a chamber for aerosol accumulation that is sufficiently rigid to withstand axial compressive forces and bending moments that may occur during manufacturing, but is in use while the article (700) is inserted into the aerosol-generating device (602). In one embodiment, the wall thickness of the cooling section (704) is approximately 0.29 mm.

[0236] The cooling section (704) provides a physical displacement between the aerosol-forming substrate (702) and the filter section (706). The physical displacement provided by the cooling section (704) provides a thermal gradient along the length of the cooling section (704) during use. In one embodiment, the cooling section (704) is configured to provide a temperature difference of at least 40°C between the heated volatile component entering the distal end of the cooling section (704) and the heated volatile component exiting the proximal end of the cooling section (704). In one embodiment, the cooling section (704) is configured to provide a temperature difference of at least 60°C between the heated volatile component entering the distal end of the cooling section (704) and the heated volatile component exiting the proximal end of the cooling section (704). This temperature difference along the length of the cooling element (704) protects the temperature-reducing filter portion (706) from the high temperature of the aerosol formed from the aerosol forming substrate (702).

[0237] In one embodiment, the length of the cooling portion (704) is at least 15 mm. In one embodiment, the length of the cooling portion (704) is 20 mm to 30 mm, more particularly 23 mm to 27 mm, more particularly 25 mm to 27 mm, more particularly 25 mm.

[0238] The cooling portion (704) is made of paper. In one embodiment, the cooling portion (704) is manufactured as a spirally wound paper tube that provides a hollow inner chamber while maintaining mechanical rigidity. The spirally wound paper tube can meet the tight dimensional accuracy requirements of the high-speed manufacturing process for tube length, outer diameter, roundness, and straightness. In another embodiment, the cooling portion (704) is a recess created from hard plug wrap or tipping paper. The hard plug wrap or tipping paper is manufactured to have sufficient rigidity to withstand axial compressive force and bending moment that may occur during manufacturing and to be used while the article (700) is inserted into the aerosol generator (602).

[0239] In each embodiment of the cooling portion (704), the dimensional accuracy of the cooling portion is sufficient to satisfy the dimensional accuracy requirements of the high-speed manufacturing process.

[0240] The filter portion (706) may be formed of any filter material sufficient to remove one or more volatile compounds from heated volatilized components from the aerosol-forming substrate (702). In one embodiment, the filter portion (706) is made of a single acetate material such as cellulose acetate. The filter portion (706) provides cooling and irritation reduction from heated volatilized components without depleting the amount of heated volatilized components to an unsatisfactory level for the user.

[0241] The density of the cellulose acetate tow material of the filter portion (706) controls the pressure drop across the filter portion (706), which in turn controls the suction resistance of the article (700). Therefore, the selection of the material of the filter portion (706) is important for controlling the suction resistance of the article (700). Additionally, the filter portion performs a filtration function in the article (700).

[0242] The presence of the filter portion (706) provides an insulating effect by providing additional cooling to the heated volatile components escaping the cooling portion (704). This additional cooling effect reduces the contact temperature of the user's lips on the surface of the filter portion (706).

[0243] One or more flavors may be added to the filter portion (706) by directly injecting a liquid having flavor into the filter portion (706) or by embedding or arranging a brittle capsule or other flavor carrier having one or more flavors inside the cellulose acetate tow of the filter portion (706). In one embodiment, the filter portion (706) has a length of 6 mm to 10 mm, more preferably 8 mm.

[0244] The mouse end portion (708) is an annular tube and defines an air gap within the mouse end portion (708). The air gap provides a chamber for heated volatile components flowing from the filter portion (706). The mouse end portion (708) is hollow to provide a chamber for aerosol accumulation, which is used while the article is inserted into the aerosol generator (602), while having sufficient rigidity to withstand axial compressive force and bending moment that may occur during manufacturing. In one embodiment, the wall thickness of the mouse end portion (708) is approximately 0.29 mm.

[0245] In one embodiment, the length of the mouse end portion (708) is 6 mm to 10 mm, more preferably 8 mm.

[0246] The mouse end portion (708) can be manufactured from a spirally wound paper tube that provides a hollow inner chamber, which maintains significant mechanical rigidity. The spirally wound paper tube can meet the strict dimensional accuracy requirements of the high-speed manufacturing process for tube length, outer diameter, roundness, and straightness.

[0247] The mouse end portion (708) provides a function to prevent any liquid condensate accumulated at the outlet of the filter portion (706) from coming into direct contact with the user.

[0248] In one embodiment, it should be understood that the mouse end portion (708) and the cooling portion (704) may be formed as a single tube, and the filter portion (706) is located inside the tube separating the mouse end portion (708) and the cooling portion (704).

[0249] Ventilation holes (707) are located in the cooling portion (704) to help cool the article (700). In one embodiment, the ventilation holes (707) include one or more rows of holes, and preferably, each row of holes is arranged circumferentially around the article (700) in a cross-section substantially perpendicular to the longitudinal axis of the article (700).

[0250] In one embodiment, there are between 1 to 4 rows of ventilation holes (707) to provide ventilation for the article (700). Each row of ventilation holes (707) may have 12 to 36 ventilation holes (707). The ventilation holes (707) may, for example, have a diameter of 100 to 500 μm. In one embodiment, the axial separation between rows of ventilation holes (707) is 0.25 mm to 0.75 mm, and more preferably, the axial separation between rows of ventilation holes (707) is 0.5 mm.

[0251] In one embodiment, the ventilation holes (707) are of uniform size. In another embodiment, the ventilation holes (707) are of varying sizes. The ventilation holes (707) may be made using any suitable technique, for example, one or more of the following techniques, before being formed into the article (700): laser technique, mechanical perforation of the cooling area (704), or preliminary perforation of the cooling area (704). The ventilation holes (707) are positioned to provide effective cooling to the article (700).

[0252] In one embodiment, the rows of ventilation holes (707) are positioned at least 11 mm from the proximal end of the article (700), and more preferably, the ventilation holes (707) are positioned 17 mm to 20 mm from the proximal end of the article (700). The position of the ventilation holes (707) is such that the user does not block the ventilation holes (707) when the article (700) is in use.

[0253] Advantageously, providing a series of ventilation holes (707) 17 mm to 20 mm from the proximal end of the article (700) allows the ventilation holes (707) to be located outside the aerosol generator (602) when the article (700) is fully inserted into the aerosol generator (602). By locating the ventilation holes (707) outside the device (602), unheated air can enter the article (700) through the ventilation holes (707) from outside the device (602), thereby helping to cool the article (700).

[0254] FIG. 10 shows a graph of temperature (404) as a function of time (402) during one heating cycle for a first part (312) of the susceptor array (310) using a reading from the first thermocouple (342) and a second part of the susceptor array (310) using a reading from the second thermocouple (344). In FIG. 10, the temperature of the first part (312) of the susceptor array (310) from the first thermocouple (342) is shown by a solid line (406). In FIG. 10, the temperature of the second part (314) of the susceptor array (310) from the second thermocouple (344) is shown by a dashed line (408).

[0255] As illustrated in FIG. 10, when heating begins, the first part (312) of the susceptor array (310) is heated rapidly during the first stage (410) and reaches the operating temperature after a first period (414) of about 60 seconds. The second part (314) of the susceptor array (310) is heated during the first stage (410), but at a much slower rate than the first part (312). The temperature of the first part (312) of the susceptor array (310) is higher than the temperature of the second part (314) of the susceptor array (310) throughout the first stage (410). The second part (314) of the susceptor array (310) does not reach the operating temperature during the first stage (410). In this embodiment, the operating temperature refers to the desired temperature at which the most desirable aerosol is released from the aerosol-forming substrate.

[0256] Also, as illustrated in FIG. 10, after the second period (416), about 150 seconds from the start of heating, the first stage (410) ends and the second stage (412) begins. In the second stage (412), the first part (312) of the susceptor array (312) is heated to a lower temperature, but is still within about 50°C of the operating temperature. Also, in the second stage (412), the second part (314) of the susceptor array (310) is rapidly heated to the operating temperature and reaches the operating temperature after the third period (418) of about 210 seconds from the start of heating.

[0257] In particular, FIG. 10 shows a preferred temperature profile for an aerosol generating system, wherein a first portion (312) of the susceptor array (310) is arranged to heat the proximal portion of the aerosol generating substrate, and a second portion (314) of the susceptor array (310) is arranged to heat the distal portion of the aerosol generating substrate. The proximal portion of the aerosol generating substrate is closer to the mouthpiece end of the aerosol generating article containing the aerosol generating substrate. This temperature profile across the aerosol generating substrate allows an aerosol with desired characteristics to be generated throughout the entire extended aerosol generating period. Heating the proximal portion of the aerosol generating substrate before heating the distal portion of the substrate facilitates optimal delivery of the generated aerosol to the user. In particular, this is believed to be because the hot aerosol from the heated proximal portion of the aerosol-forming substrate does not interact with the unheated distal portion of the aerosol-forming substrate during the first stage, and thus the hot aerosol from the proximal portion does not release volatile compounds from the distal portion.

[0258] This temperature profile can be achieved by driving a variable current, preferably an AC current, in the first inductor coil (312) and the second inductor coil (314) in various ways. For example, in the first step, the first variable current, preferably an AC current, can be driven in the first inductor coil (312) in a first duty cycle, and the second variable current, preferably an AC current, can be driven in the second inductor coil (314), and the duty cycle of the second variable current is less than the duty cycle of the first variable current, so that the current driven in the first inductor coil (312) is greater than the current driven in the second inductor coil (314) during the first step. In some embodiments, it will be understood that the variable current is not supplied to the second inductor coil (314) in the first step (410). In the second step, the opposite may be applied, so that the duty cycle of the first variable current is lower than the duty cycle of the second variable current.

[0259] In FIG. 11, an induction heating array (501) is illustrated. The induction heating array (501) includes a first LC circuit (510). The first LC circuit (510) includes a first inductor coil (512) and a first capacitor (514). The first inductor coil (512) has a first inductance. The first capacitor (514) has a first capacitance. The resonant frequency of the first LC circuit (510) is determined by the first inductance and the first capacitance.

[0260] FIG. 11 further shows a first transistor (516), such as an FET, connected to the first LC circuit (510). Also, a terminal (518) of a DC power supply is shown in FIG. 11. The terminal (518) of the DC power supply is connected to the power supply of the device, preferably a battery. The first LC circuit (510) is configured to inductively heat a first portion of a susceptor array. The first portion of the susceptor array may be arranged adjacent to a first inductor coil so that the first inductor coil can heat the first portion of the susceptor element by either or both of eddy current and hysteresis.

[0261] The induction heating array (501) of FIG. 11 also includes a second LC circuit (520) comprising a second inductor coil (522) and a second capacitor (524). A second transistor (526) is coupled to the second LC circuit (520).

[0262] The first transistor (516) is configured to control the operation of the first LC circuit (510). The second transistor (526) is configured to control the operation of the second LC circuit (520).

[0263] The components of the second LC circuit (520) may be similar to the components of the first LC circuit (510). That is, the second inductor coil (522) may have a second inductance, the second capacitor (524) may have a second capacitance, and the second transistor (526) may be a FET. The two LC circuits (510, 520) may be connected in parallel to a DC power supply.

[0264] FIG. 12 shows a controller (527) in addition to a power stage (528). The power stage (528) may include a first LC circuit (510) and a first transistor (516) as shown in FIG. 11. Alternatively, the power stage (528) may include all the components shown in FIG. 11. The controller (527) shown in FIG. 12 may include an oscillator (530). The oscillator (530) may be connected to one or both of the first transistor (516) and the second transistor (526). A DC power supply (532) is also shown in FIG. 12. The DC power supply (532) may be used to supply power to the elements shown in FIG. 11. Additionally, the DC power supply (532) may be used to supply power to the controller (527), preferably the oscillator (530).

[0265] The controller (527) further includes a pulse width modulation module (534). The pulse width modulation module (534) may be configured to modulate a signal used to drive the LC circuit (510, 520). The controller (527) may be configured to drive the LC circuit (510, 520). That is, the controller (527) may be configured to supply an electrical signal to the LC circuit (510, 520).

[0266] The controller (527) may be configured to drive the first LC circuit (510) with an AC current of a first frequency. The first frequency may correspond to the resonant frequency of the first LC circuit (510). The controller (527) may be configured to drive the second LC circuit (520) with an AC current of a second frequency. The second frequency may correspond to the resonant frequency of the second LC circuit (520).

[0267] The resonant frequency of the first LC circuit (510) may be the same as the resonant frequency of the second LC circuit (520). In this scenario, the controller (527) may be configured to supply AC current to the first LC circuit (510) at a frequency corresponding to the resonant frequency of the first LC circuit (510) during the first stage. The first stage may be a stage in which a first portion of the aerosol-forming substrate is heated primarily by a first portion of the susceptor array. During the first stage, the controller (527) may be configured to supply AC current to the second LC circuit (520) at a frequency different from the resonant frequency of the second LC circuit (520). Consequently, the second LC circuit (520) will be heated to a lower temperature than the first LC circuit (510). In the second step, where the second part of the aerosol-forming substrate is heated primarily by the second part of the susceptor array, a complementary AC current may be supplied to the LC circuit (510, 520) by a controller. In the second step, an AC current corresponding to the resonant frequency of the second LC circuit (520) may be supplied to the second LC circuit (520), and an AC current at a frequency different from the resonant frequency of the first LC circuit (510) may be supplied to the first LC circuit (510).

[0268] The resonant frequency of the first LC circuit (510) may be different from the resonant frequency of the second LC circuit (520). In this case, during the first stage, the controller (527) may be configured to supply AC current to the first LC circuit (510) at a frequency corresponding to the resonant frequency of the first LC circuit (510). AC current having the same frequency may be supplied to the second LC circuit (520). Because the resonant frequency of the second LC circuit (520) is different from the resonant frequency of the first LC circuit (510), the second LC circuit (520) may only heat the second part of the susceptor array to a lower temperature than the first LC circuit (510) which heats the first part of the susceptor array. In the second stage where heating of the second part of the susceptor array is required, the controller (527) may be configured to supply an AC current at a frequency corresponding to the resonant frequency of the second LC circuit (520), while this AC current will reduce the heating of the first part of the susceptor array by the first LC circuit (510).

[0269] FIG. 13 shows an embodiment in which the first LC circuit (510) is heated primarily in the first stage, while the second LC circuit (520) is heated to a lower temperature during the first stage. This is reversed in the second stage, where the first LC circuit (510) is heated to a lower temperature than the second LC circuit (520). To facilitate this, pulse width modulation is used. More specifically, the top of FIG. 13 shows the complementary duty cycle of the first alternating pulse width modulation signal (top left) and the second alternating pulse width modulation signal (top right). The first alternating pulse width modulation signal will be referred to herein as the first signal (536). The second alternating pulse width modulation signal will be referred to herein as the second signal (538). A duty cycle refers to a percentage of the time each signal is turned on. As can be seen in FIG. 13, the first signal (536) has a high duty cycle of about 80%, while the second signal (538) has a low duty cycle of about 20%. The embodiment illustrated in FIG. 13 corresponds to a first stage in which the first part (541) of the susceptor array (540) is heated mainly, while the second part (542) of the susceptor array (540) is heated to a lower temperature. Below the signal illustrated in FIG. 13, a first inductor coil (512) and a second inductor coil (522) are illustrated. Below the inductor coils (512, 522), a susceptor array (540) comprising the first part (541) and the second part (542) is illustrated. Below the susceptor array (540), an aerosol generating article (542) comprising an aerosol forming substrate is illustrated. Below the aerosol generating article (542), a diagram (544) showing heat according to distance is shown. Heat is mainly high in the first part (541) of the susceptor array (540), but heat is lower in the second part (542) of the susceptor array (540). During the second stage, the heating of the susceptor array (540) will be different.During the second stage, the second LC circuit (520) will heat the second part (542) of the susceptor array (540) to a higher temperature, and the temperature of the first part (541) of the susceptor array (540) will be lower than in the first stage. To facilitate this, pulse width modulation may be used similarly to in the first stage. The duty cycle of the second signal (538) may be increased, while the duty cycle of the first signal (536) may be decreased. The degree may be gradual from the first stage to the second stage. The duty cycle of the first signal (536) and the duty cycle of the second signal (538) may be added up to 100%. Alternatively, the duty cycle of the first signal (536) and the duty cycle of the second signal (538) may be added up to an amount lower than 100%. For example, in the first stage, the duty cycle of the first signal (536) may exceed 50%, e.g. 80%, and the duty cycle of the second signal (538) may be close to 0% or 0%; and during the second stage, the opposite may be true.

[0270] It will be understood that the foregoing embodiments are merely specific examples, and that other embodiments are considered in accordance with the present disclosure.

Claims

Claim 1 An aerosol generating device comprising an induction heating array configured to heat an aerosol forming substrate and a controller, wherein the induction heating array comprises: a susceptor array capable of being heated by penetrating a variable magnetic field to heat the aerosol forming substrate; at least a first inductor coil; and at least a second inductor coil, wherein the controller is configured to drive the first inductor coil with a first alternating pulse width modulation signal to generate a first alternating magnetic field to heat a first portion of the susceptor array, wherein the controller is configured to drive the second inductor coil with a second alternating pulse width modulation signal to generate a second alternating magnetic field to heat a second portion of the susceptor array, and wherein the controller is configured to supply the first alternating pulse width modulation signal and the second alternating pulse width modulation signal with a complementary duty cycle. Claim 2 An aerosol generating device according to claim 1, wherein the controller is configured to supply the first alternating pulse width modulation signal to the first inductor coil during a first step to increase the temperature of the first part of the susceptor array from an initial temperature to a first operating temperature, and the controller is configured to supply the first alternating pulse width modulation signal with a duty cycle of more than 50% during the first step. Claim 3 An aerosol generating device according to paragraph 2, wherein the controller is configured to supply the first alternating pulse width modulation signal to the first inductor coil during a second step to reduce the temperature of the first part of the susceptor array from the first operating temperature to the second operating temperature, and the controller is configured to supply the first alternating pulse width modulation signal with a duty cycle of less than 50% during the second step. Claim 4 An aerosol generating device according to claim 3, wherein the controller is configured to supply the second alternating pulse width modulation signal to the second inductor coil during the first step to increase the temperature of the second part of the susceptor array from an initial temperature to a third operating temperature lower than the first operating temperature, and the controller is configured to supply the second alternating pulse width modulation signal with a duty cycle of less than 50% during the first step. Claim 5 An aerosol generating device according to claim 4, wherein the controller is configured to supply the second alternating pulse width modulation signal to the second inductor coil during the second step to increase the temperature of the second part of the susceptor array from the third operating temperature to a fourth operating temperature higher than the second operating temperature, and the controller is configured to supply the second alternating pulse width modulation signal with a duty cycle of more than 50% during the second step. Claim 6 An aerosol generating device according to claim 1, wherein the aerosol generating device further comprises a power supply unit for providing power to the induction heating array. Claim 7 An aerosol generating device according to claim 1, wherein the controller includes a microcontroller. Claim 8 An aerosol generating device according to claim 7, wherein the microcontroller is configured to use the clock frequency of the microcontroller as one or both of the frequencies of the first alternating pulse width modulation signal and the second alternating pulse width modulation signal. Claim 9 The aerosol generating device according to claim 1, wherein the aerosol generating device further comprises an oscillator for generating one or both of the frequencies of the first alternating pulse width modulation signal and the second alternating pulse width modulation signal. Claim 10 The aerosol generating device according to claim 1, wherein the aerosol generating device further comprises a first power stage, wherein the first power stage comprises at least the first inductor coil and the first capacitor. Claim 11 An aerosol generating device according to claim 10, wherein the first inductor coil and the first capacitor are arranged as a first LC circuit. Claim 12 The aerosol generating device according to claim 1, wherein the aerosol generating device further comprises a second power stage, wherein the second power stage comprises at least the second inductor coil and the second capacitor. Claim 13 An aerosol generating device according to claim 12, wherein the second inductor coil and the second capacitor are arranged as a second LC circuit. Claim 14 An aerosol generating device according to claim 1, wherein the second inductor coil is wound in a different direction from the first inductor coil. Claim 15 An aerosol generating device according to claim 1, wherein the second inductor coil has a different number of turns compared to the first inductor coil. Claim 16 An aerosol generating device according to claim 1, wherein the second inductor coil has a different length with respect to the first inductor coil. Claim 17 The aerosol generating device according to claim 1, wherein the aerosol generating device comprises a device cavity configured to accommodate an aerosol forming substrate, the first inductor coil is disposed around the device cavity, and the second inductor coil is disposed around the device cavity. Claim 18 An aerosol generating device according to claim 17, wherein the device cavity has a proximal end and a distal end opposite to the proximal end, and the proximal end of the device cavity is substantially open to receive an aerosol generating article. Claim 19 An aerosol generating device according to claim 18, wherein the first inductor coil is arranged toward the proximal end of the device cavity and the second inductor coil is arranged toward the distal end of the device cavity. Claim 20 An aerosol generating system comprising an aerosol generating article comprising an aerosol generating device and an aerosol forming substrate according to any one of claims 1 to 19. Claim 21 A method for controlling an aerosol generating device, wherein the aerosol generating device comprises: an induction heating array configured to heat an aerosol forming substrate, and a controller, wherein the induction heating array comprises: a susceptor array capable of being heated by penetrating a variable magnetic field to heat the aerosol forming substrate, at least a first inductor coil, and at least a second inductor coil, wherein the controller is configured to drive the first inductor coil and the second inductor coil, and the method comprises the steps of: driving the first inductor coil with a first alternating pulse width modulation signal to generate a first alternating magnetic field for heating a first portion of the susceptor array; driving the second inductor coil with a second alternating pulse width modulation signal to generate a second alternating magnetic field for heating a second portion of the susceptor array; and supplying the first alternating pulse width modulation signal with a duty cycle complementary to the duty cycle of the second alternating pulse width modulation signal. Claim 22 A method according to claim 21, wherein the first alternating pulse width modulation signal is supplied to the first inductor coil during a first step to increase the temperature of the first part of the susceptor array from an initial temperature to a first operating temperature, and the first alternating pulse width modulation signal is supplied during the first step with a duty cycle of more than 50%. Claim 23 A method according to claim 22, wherein the first alternating pulse width modulation signal is supplied to the first inductor coil during a second step to reduce the temperature of the first part of the susceptor array from the first operating temperature to the second operating temperature, and the first alternating pulse width modulation signal is supplied during the second step with a duty cycle of less than 50%. Claim 24 A method according to claim 23, wherein the second alternating pulse width modulation signal is supplied to the second inductor coil during the first step to increase the temperature of the second part of the susceptor array from an initial temperature to a third operating temperature, and the second alternating pulse width modulation signal is supplied during the first step with a duty cycle of less than 50%. Claim 25 A method according to claim 24, wherein the second alternating pulse width modulation signal is supplied to the second inductor coil during the second step to increase the temperature of the second part of the susceptor array from the third operating temperature to the fourth operating temperature, and the second alternating pulse width modulation signal is supplied during the second step with a duty cycle of more than 50%. Claim 26 A method according to claim 21 or 22, wherein the aerosol generating device is an aerosol generating device according to any one of claims 1 to 19.

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