Aerosol-generating system with detection of liquid aerosol-forming substrate supply to susceptor elements

Abstract

A power circuit (66) for an aerosol-generating device (60) configured to heat a susceptor element (16, 18) to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element (16, 18). The power supply circuit (66) comprises an inductor coil (68) for generating an alternating magnetic field for heating the susceptor element (16, 18) to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element (16, 18); a power source (72); and a controller (70). The controller (70) is configured to: control at least one of a current and a voltage between the power source (72) and the inductor coil (68); comparing at least one of a current and a voltage between the power source (72) and the inductor coil (68) to a dry receptor threshold; and determining whether the susceptor element (16, 18) is supplied with the liquid aerosol-forming substrate based on the comparison. An aerosol-generating device (60) comprising the power circuit (66), an aerosol-generating system comprising the aerosol-generating device (60), and a method of operating an aerosol-generating device (60) comprising the power circuit (66) are also provided.

Description

[0001] The present disclosure relates to a power supply circuit for an aerosol generating device, an aerosol generating device comprising the power supply circuit, an aerosol generating system comprising the aerosol generating device, and a method of operating an aerosol generating device. More specifically, the present disclosure relates to a power supply circuit for an aerosol generating device, the power supply circuit being configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element.

[0002] Aerosol generating systems that use induction heating to heat a liquid aerosol-forming substrate so as to generate an aerosol for a user to inhale are generally known in the prior art. These systems generally include: an aerosol generating device including an induction heating component, and a barrel including a liquid aerosol-forming substrate, the liquid aerosol-forming substrate being capable of releasing volatile compounds when heated, and the volatile compounds cooling to form an inhalable aerosol. The barrel is configured to be connected to the aerosol generating device. The induction heating component includes an inductor coil, which is configured to generate an alternating magnetic field. A susceptor element forming a part of the barrel or device is arranged in close proximity to the aerosol-forming substrate and within the alternating magnetic field. When the susceptor element is penetrated by the alternating magnetic field, the susceptor element is heated by at least one of Joule heating and hysteresis losses from the induced eddy current in the susceptor element. The heated susceptor element heats the liquid aerosol-forming substrate supplied to the susceptor element, so that the volatile compounds are released from the liquid aerosol-forming substrate, and the volatile compounds cool to form an inhalable aerosol.

[0003] Typically, an aerosol generating device is reusable and the liquid aerosol-forming substrate is contained in a disposable cartridge. In use, the liquid aerosol-forming substrate evaporates to generate an aerosol, and after a period of use, such as a predetermined number of puffs by a user, the liquid aerosol-forming substrate will be exhausted. Once the liquid aerosol-forming substrate is exhausted, the cartridge should be replaced before the subsequent use of the aerosol generating device.

[0004] It is desirable to provide an aerosol generating device that is capable of detecting when insufficient liquid aerosol-forming substrate is supplied to a susceptor element to generate an aerosol. It is desirable to provide an aerosol generating device that is capable of detecting when the liquid aerosol-forming substrate in a cartridge is depleted.

[0005] According to the present disclosure, a power supply circuit for an aerosol generating device is provided. The aerosol generating device is configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element. The power supply circuit may include an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element. The power supply circuit may also include a power supply; and a controller. The controller may be configured to control at least one of a current and a voltage between the power supply and the inductor coil. The controller may also be configured to compare at least one of a current and a voltage between the power supply and the inductor coil with a dry susceptor threshold. The controller may also be configured to determine whether the susceptor element is supplied with a liquid aerosol-forming substrate based on the comparison.

[0006] The inventors have realised that, while the susceptor element is supplied with a liquid aerosol-forming substrate, the current and voltage supplied by the power supply to the inductor coil remain substantially constant while the liquid aerosol-forming substrate is heated and evaporated. Therefore, a sufficiently large deviation of at least one of the current and voltage supplied from the power supply to the inductor coil from a constant value achieved while the liquid aerosol-forming substrate is heated and evaporated may indicate that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0007] Determining whether the susceptor element is supplied with a liquid aerosol-forming substrate may be beneficial for several reasons. For example, determining that the susceptor element is not supplied with a liquid aerosol-forming substrate may indicate that a reservoir of the liquid aerosol-forming substrate is exhausted and needs to be refilled or replaced. For example, determining that the susceptor element is not supplied with a liquid aerosol-forming substrate may indicate that the device is not functioning properly. For example, determining that the susceptor element is not supplied with a liquid aerosol-forming substrate may indicate that the aerosol generating device is not generating the expected amount or quality of aerosol because not enough liquid aerosol-forming substrate is supplied to the susceptor element.

[0008] In some embodiments, the controller is configured to notify a user when it is determined that the susceptor element is not supplied with liquid aerosol-forming substrate.

[0009] The controller may be configured to notify the user in any suitable manner. The controller may be configured to send a notification signal when it is determined that the receptor element is not supplied with a liquid aerosol-forming substrate. The controller may be configured to provide a visual notification to the user. For example, the controller may be configured to illuminate a light emitting diode to notify the user. The controller may be configured to display the notification on a display. The controller may be configured to provide an audible notification to the user. For example, the controller may be configured to activate a buzzer, or play a sound through a speaker to notify the user.

[0010] In some preferred embodiments, the controller is configured to control at least one of a current and a voltage from a power source to the inductor coil such that power is supplied to the inductor coil to heat a susceptor element coupled to the inductor coil, thereby generating an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element.

[0011] The controller may be configured to control at least one of a current and a voltage from the power source to the inductor coil such that between about 6 watts and about 12 watts of power are supplied to the inductor coil. The controller may be configured to control at least one of a current and a voltage from the power source to the inductor coil such that between about 8 watts and about 10 watts of power are supplied to the inductor coil.

[0012] In some of these preferred embodiments, the controller is further configured to prevent current from being supplied to the inductor coil from the power supply when it is determined that the susceptor element is not supplied with liquid aerosol-forming substrate.

[0013] The controller may be configured to control at least one of a current and a voltage between the power source and the inductor coil. In some embodiments, the controller is configured to control the voltage between the power source and the inductor coil. In some preferred embodiments, the controller is configured to control the current between the power source and the inductor coil.

[0014] In some embodiments, the controller is configured to measure a voltage between the power source and the inductor coil.

[0015] In some preferred embodiments, the controller is configured to measure the current between the power source and the inductor coil.

[0016] The controller may be configured to measure the voltage and current between the power source and the inductor coil.

[0017] The voltage may be any suitable voltage. The voltage may be a supply voltage from a power supply. Preferably, the power supply is a DC power supply and the voltage is a DC supply voltage from the DC power supply. In some preferred embodiments, the power supply electronics may include a DC / DC converter. The DC / DC converter may receive a DC supply voltage from the DC power supply. The output of the DC / DC converter may be received by a DC / AC converter. The voltage may be the output of the DC / DC converter.

[0018] The current may be any suitable current.In some preferred embodiments, as described in more detail below, the power electronics may include a DC / AC converter, and the current may include a DC current received by the DC / AC converter.

[0019] The controller may be configured to compare at least one of the current and voltage between the power supply and the inductor coil to a dry receptor threshold. The dry receptor threshold may be any suitable threshold. The dry receptor threshold may be a threshold stored in a memory of the controller.

[0020] In some embodiments, the dry receptor threshold is recorded in a memory of the controller at the factory prior to use of the aerosol generating device.

[0021] In some preferred embodiments, the dry receptor threshold is determined by the power circuit system and stored in the memory of the controller. In the case of determining the dry receptor threshold, the controller can be configured to measure at least one of the initial current and the initial voltage between the power supply and the inductor coil, and determine the dry receptor threshold based on at least one of the measured initial current and the measured initial voltage. The measurement of at least one of the initial current and the initial voltage can be performed at any suitable time. When the aerosol generating device is first turned on, the measurement of at least one of the initial current and the initial voltage can be performed. When the aerosol generating device is first turned on, the measurement of at least one of the initial current and the initial voltage can be performed. When the first puff is taken on the aerosol generating device, the measurement of at least one of the initial current and the initial voltage can be performed. In the case where the aerosol generating system includes an aerosol generating device and a cartridge that can be connected to the aerosol generating device, the measurement of at least one of the initial current and the initial voltage can be performed when the cartridge is first connected to the aerosol generating device.

[0022] In some embodiments, the dry susceptor threshold is a maximum threshold above which it can be determined that the susceptor element is not supplied with liquid aerosol-forming substrate.

[0023] In some embodiments, the dry susceptor threshold is a minimum threshold below which it can be determined that the susceptor element is not supplied with liquid aerosol-forming substrate.

[0024] The comparison of at least one of the current and the voltage between the power supply and the sensor coil with the dry receptor threshold may be a comparison of the voltage between the power supply and the sensor coil with the dry receptor threshold. The comparison of at least one of the current and the voltage between the power supply and the sensor coil with the dry receptor threshold may be a comparison of the current between the power supply and the sensor coil with the dry receptor threshold. The comparison of at least one of the current and the voltage between the power supply and the sensor coil with the dry receptor threshold may be a comparison of both the current and the voltage between the power supply and the sensor coil with the dry receptor threshold.

[0025] The controller may be further configured to determine whether the susceptor element is supplied with liquid aerosol-forming substrate based on the comparison.

[0026] In some embodiments, the controller may be configured to determine that the susceptor element is not supplied with a liquid aerosol-forming substrate when at least one of the current and the voltage between the power supply and the sensor coil is greater than a dry susceptor threshold. In some embodiments, the controller may be configured to determine that the susceptor element is not supplied with a liquid aerosol-forming substrate when at least one of the current and the voltage between the power supply and the sensor coil is less than a dry susceptor threshold.

[0027] Determining that the susceptor element is not supplied with liquid aerosol-forming substrate may depend on the characteristics of the susceptor element. However, typically for a susceptor comprising a material having a positive temperature coefficient, a comparison of the current between the power supply and the sensor coil with the sensor coil will indicate that the susceptor element is not supplied with liquid aerosol-forming substrate when the current between the power supply is less than the dry susceptor threshold.

[0028] Where the dry susceptor threshold is based on a measurement of an initial current between the power supply and the inductor coil, the dry susceptor threshold may be at least 20% less than the measurement of the initial current. The dry susceptor threshold may be 15% to 50% less than the measurement of the initial current.

[0029] In some preferred embodiments, the controller is further configured to determine an equivalent resistance or an apparent resistance.As used herein, references to "resistance" refer to electrical ohmic resistance unless expressly indicated otherwise.

[0030] The controller may be configured to determine an equivalent resistance based on a quotient of a voltage and a current between the power source and the inductor coil. The equivalent resistance includes the resistance of the inductor coil and an apparent resistance of the susceptor element. The apparent resistance of the susceptor element is the additional resistance "seen" by the inductor coil when the susceptor element is coupled to the inductor coil. The apparent resistance of the susceptor element may be determined by subtracting the resistance of the coil from the equivalent resistance determined based on the quotient of the voltage and the current between the power source and the inductor coil.

[0031] In some of these preferred embodiments, the controller may be configured to compare the determined equivalent resistance to a dry susceptor threshold. In some of these preferred embodiments, the controller may be configured to compare the determined apparent resistance of the susceptor element to a dry susceptor threshold. In these preferred embodiments, the dry susceptor threshold may be at least 1.05 ohms. The dry susceptor threshold may be between about 1.05 ohms and 2.20 ohms.

[0032] In some embodiments, the controller is configured to control at least one of a current and a voltage between the power source and the inductor coil that corresponds to a target equivalent resistance or a target apparent resistance of the susceptor element. In these embodiments, the controller may be configured to determine the equivalent resistance or the apparent resistance of the susceptor element and control at least one of a current and a voltage between the power source and the inductor coil to achieve the target equivalent resistance or the target apparent resistance of the susceptor element. The target equivalent resistance or the target apparent resistance of the susceptor element may be between about 0.25 ohms and about 1.7 ohms.

[0033] In these embodiments, the dry susceptor threshold may be at least 15% greater than the target equivalent resistance or target apparent resistance of the susceptor element. The dry susceptor threshold may be at least 20% greater than the target equivalent resistance or target apparent resistance of the susceptor element. The dry susceptor threshold may be 15% to 50% greater than the target equivalent resistance or target apparent resistance of the susceptor element.

[0034] As described above, determining that the susceptor element is not supplied with a liquid aerosol-forming substrate may depend on the characteristics of the susceptor element. However, typically for a susceptor comprising a material having a positive temperature coefficient, a comparison of the determined equivalent resistance with the dry susceptor threshold will indicate that the susceptor element is not supplied with a liquid aerosol-forming substrate when the determined equivalent resistance is greater than the dry susceptor threshold.

[0035] In the case where the dry susceptor threshold is based on a measurement of at least one of an initial current and an initial voltage between the power supply and the inductor coil, the controller may be configured to determine an initial equivalent resistance or an initial apparent resistance of the susceptor element based on the measurement of at least one of the initial current and the initial voltage. In the case where the controller is configured to compare the determined equivalent resistance or the apparent resistance of the susceptor element with the dry susceptor threshold, the dry susceptor threshold may be at least 20% greater than the determined initial equivalent resistance or the determined initial apparent resistance of the susceptor element. The dry susceptor threshold may be 15% to 50% greater than the determined initial equivalent resistance or the determined initial apparent resistance of the susceptor element.

[0036] In some preferred embodiments, the controller is further configured to determine an equivalent conductance or an apparent conductance. The controller may be configured to determine the equivalent conductance based on the quotient of the current and the voltage between the power source and the inductor coil. The equivalent conductance includes the conductance of the inductor coil and the apparent conductance of the susceptor element. The apparent conductance of the susceptor element is the change in conductance "seen" by the inductor coil when the susceptor element is coupled to the inductor coil. The apparent conductance of the susceptor element may be determined by subtracting the conductance of the coil from the equivalent conductance determined based on the quotient of the current and the voltage between the power source and the inductor coil.

[0037] In some of these preferred embodiments, the controller may be configured to compare the determined equivalent conductance to a dry receptor threshold. In some of these preferred embodiments, the controller may be configured to compare the determined apparent conductance of the receptor element to a dry receptor threshold. In these preferred embodiments, the dry receptor threshold may be no less than 0.95 Siemens. The dry receptor threshold may be between about 0.70 Siemens and about 0.95 Siemens.

[0038] In some embodiments, the controller is configured to control at least one of a current and a voltage between the power source and the inductor coil corresponding to a target equivalent conductance or a target apparent conductance of the susceptor element. In these embodiments, the controller may be configured to determine the equivalent conductance or the apparent conductance of the susceptor element and control at least one of a current and a voltage between the power source and the inductor coil to achieve the target equivalent conductance or the target apparent conductance of the susceptor element. The target equivalent conductance or the target apparent conductance of the susceptor element is between about 0.60 Siemens and about 4.00 Siemens.

[0039] In these embodiments, the dry susceptor threshold may be at least 15% less than the target equivalent conductance or target apparent conductance of the susceptor element. The dry susceptor threshold may be at least 20% less than the target equivalent conductance or target apparent conductance of the susceptor element. The dry susceptor threshold may be 15% to 50% less than the target equivalent conductance or target apparent conductance of the susceptor element.

[0040] As described above, determining that the susceptor element is not supplied with a liquid aerosol-forming substrate may depend on the characteristics of the susceptor element. However, typically for a susceptor comprising a material having a positive temperature coefficient, a comparison of the determined equivalent conductance with the dry susceptor threshold will indicate that the susceptor element is not supplied with a liquid aerosol-forming substrate when the determined equivalent conductance is less than the dry susceptor threshold.

[0041] In the case where the dry susceptor threshold is based on a measurement of at least one of an initial current and an initial voltage between the power supply and the inductor coil, the controller may be configured to determine an initial equivalent conductance or an initial apparent conductance of the susceptor element based on the measurement of at least one of the initial current and the initial voltage. In the case where the controller is configured to compare the determined equivalent conductance or the determined initial apparent conductance of the susceptor element with the dry susceptor threshold, the dry susceptor threshold may be at least 20% less than the determined initial equivalent conductance or the determined initial apparent conductance of the susceptor element. The dry susceptor threshold may be 15% to 50% less than the determined initial equivalent conductance or the determined initial apparent conductance of the susceptor element.

[0042] The power circuit includes an inductor coil.

[0043] The inductor coil may have any suitable form. In some embodiments, the inductor coil is a tubular coil. In some embodiments, the inductor coil is a helical coil. In some embodiments, the inductor coil is a planar coil or a flat coil.

[0044] The power supply circuit may further comprise at least one flux concentrator arranged to contain the alternating magnetic field generated by the inductor coil.

[0045] The power circuit may include any suitable number of inductor coils. The power circuit may include a single inductor coil. The power circuit may include multiple inductor coils. The power circuit may include one, two, three, four, five, six, seven, or eight inductor coils.

[0046] The power source may be any suitable power source. Preferably, the power source is a DC power source. The power source may be a battery. The battery may be a lithium-based battery, such as a lithium cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. The battery may be a nickel metal hydride battery or a nickel cadmium battery. The power source may be another form of charge storage device, such as a capacitor. The power source may be rechargeable and configured for many charge and discharge cycles. The power source may have a capacity that allows storage of energy sufficient for one or more user experiences of the aerosol generating system; for example, the power source may have sufficient capacity to allow continuous generation of aerosol for a period of about six minutes (corresponding to the typical time spent smoking a conventional cigarette), or for a period of time that is a multiple of six minutes. In another example, the power source may have a capacity sufficient to perform a predetermined number of puffs or to discontinuously activate the atomizer assembly.

[0047] The controller may be any suitable controller. The controller may include a memory. The dry receptor threshold may be stored in the memory of the controller. The controller may include a microprocessor. The microprocessor may be a programmable microprocessor, a microcontroller, or an application specific integrated chip (ASIC) or other electronic circuit system capable of providing control. The controller may be configured to continuously supply power to the inductor coil after activation of the device, or may be configured to supply power intermittently, such as on a puff-by-puff basis. Power may be supplied to the inductor coil in the form of current pulses, for example by means of pulse width modulation (PWM).

[0048] The controller may be configured to supply an alternating current to the inductor coil. As used herein, "alternating current" means an electric current that periodically reverses direction. The alternating current may have any suitable frequency. A suitable frequency for the alternating current may be between 100 kilohertz (kHz) and 30 megahertz (MHz). In the case where the inductor coil is a solenoid coil or a tubular coil, the alternating current may have a frequency between 500 kilohertz (kHz) and 30 megahertz (MHz). In the case where the inductor coil is a flat coil, the alternating current may have a frequency between 100 kilohertz (kHz) and 1 megahertz (MHz).

[0049] Driving an alternating current through the inductor coil causes the inductor coil to generate an alternating magnetic field. The alternating magnetic field may have any suitable frequency for heating a heating portion of a susceptor element located in the alternating magnetic field. Suitable frequencies of the alternating magnetic field may be between 100 kilohertz (kHz) and 30 megahertz (MHz).

[0050] The power supply circuit may include further electronic components. For example, in some embodiments, the controller may include any one of a sensor, a switch, a display element.

[0051] In the case where the power supply is a DC power supply, the power supply circuit may further include a DC / AC converter. The DC / AC converter may be arranged between the DC power supply and the inductor coil. The DC / AC converter may include a capacitor. The DC / AC converter may include an LC (inductor capacitor) load network.

[0052] In some preferred embodiments, the DC / AC converter may include a capacitor, wherein the DC / AC converter further includes an LC (inductor capacitor) load network, and wherein the LC load network includes an inductor coil and a capacitor. In some of these preferred embodiments, the inductor coil is connected in series with the capacitor.

[0053] In some preferred embodiments, the DC / AC converter comprises a class E power amplifier. The DC / AC converter may comprise a class D power amplifier.

[0054] In some embodiments, the power supply circuit may further include a DC / DC converter. The DC / AC converter may be arranged between the DC power supply and the DC / AC converter. The DC / DC converter may enable a DC power supply with a different supply voltage to be used with the aerosol generating device without changing the function of the aerosol generating device.

[0055] The power circuit may also include a puff detector. The puff detector may be configured to detect when a user puffs on the aerosol generating system. The puff detector may be any suitable sensor capable of detecting when a user puffs on the aerosol generating device. For example, the puff detector may be an airflow sensor.

[0056] Where the power circuit comprises a puff detector, the controller may be configured to supply current and voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate an aerosol when the puff detector detects that the user has puffed on the aerosol generating device. The controller may also be configured to prevent current and voltage from being supplied to the inductor coil to not generate an alternating magnetic field to heat the susceptor element and generate an aerosol when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0057] There is also provided an aerosol generating device configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, wherein the aerosol generating device comprises a power supply circuit as described above.

[0058] It is contemplated that an aerosol generating device may be provided, the aerosol generating device being configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating device being connectable to a cartridge including a susceptor element. The aerosol generating device may include a power supply circuit including an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element. The power supply circuit may also include a power supply; and a controller. The controller may be configured to control at least one of a current and a voltage between the power supply and the inductor coil. The controller may also be configured to compare at least one of a current and a voltage between the power supply and the inductor coil with a dry susceptor threshold. The controller may also be configured to determine whether the susceptor element is supplied with a liquid aerosol-forming substrate based on the comparison.

[0059] In some preferred embodiments, the aerosol generating device may further include a cavity configured to receive a portion of the cartridge to couple the cartridge to the aerosol generating device. In some of these preferred embodiments, the inductor coil is arranged at or around the cavity. Preferably, the inductor coil is arranged to generate an alternating magnetic field in the cavity. The inductor coil may at least partially define the cavity.

[0060] An aerosol generating system is also provided, comprising an aerosol generating device having a power supply circuit as described above, and a cartridge comprising a liquid reservoir for holding a liquid aerosol-forming substrate. In some embodiments, the aerosol generating device comprises a susceptor element. In some preferred embodiments, the cartridge comprises a susceptor element.

[0061] In particular, there is provided an aerosol generating system comprising: a cartridge having a susceptor element and a liquid aerosol-forming substrate supplied to the susceptor element; and an aerosol generating device as described above having a power supply circuit as described above.

[0062] It is contemplated that an aerosol generating system may be provided, comprising a cartridge; and an aerosol generating device. The cartridge may comprise: a susceptor element; and a liquid aerosol-forming substrate supplied to the susceptor element. The aerosol generating device may be connectable to the cartridge. The aerosol generating device may be configured to heat the susceptor element to generate an aerosol from the liquid aerosol-forming substrate supplied to the susceptor element. The aerosol generating device may comprise a power supply circuit. The power supply circuit may comprise an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from the liquid aerosol-forming substrate supplied to the susceptor element. The power supply circuit may further comprise: a power supply; and a controller. The controller may be configured to control at least one of a current and a voltage between the power supply and the inductor coil. The controller may further be configured to compare at least one of a current and a voltage between the power supply and the inductor coil with a dry susceptor threshold. The controller may further be configured to determine whether the susceptor element is supplied with a liquid aerosol-forming substrate based on the comparison.

[0063] As used herein, "susceptor element" means an element that can be heated by the penetration of an alternating magnetic field. The susceptor element is generally heatable by at least one of Joule heating and hysteresis losses through eddy currents induced in the susceptor element.

[0064] Possible materials for the susceptor element include graphite, molybdenum, silicon carbide, stainless steel, niobium, aluminum, and virtually any other conductive element. The susceptor element may be a ferrite element. The material and geometry of the susceptor element may be selected to provide the desired resistance and heat generation.

[0065] The susceptor element may include a magnetic material that can be heated by the penetration of an alternating magnetic field. The term "magnetic material" is used herein to describe a material that can interact with a magnetic field, including both paramagnetic materials and ferromagnetic materials. The magnetic material may be any suitable magnetic material that can be heated by the penetration of an alternating magnetic field. In some preferred embodiments, the magnetic material includes ferritic stainless steel. Suitable ferritic stainless steels include SAE 400 series stainless steels, such as SAE 409, 410, 420, and 430 stainless steels.

[0066] The susceptor element may have any suitable form. The susceptor element may comprise, for example, a mesh, a flat spiral coil, fibers or a fabric. The susceptor element may be fluid permeable.

[0067] In some preferred embodiments, the susceptor element is planar.A planar susceptor element may extend substantially in a plane.

[0068] In some preferred embodiments, the susceptor element comprises a mesh. The susceptor element may comprise an array of filaments forming a mesh. As used herein, the term "mesh" encompasses grids and arrays of filaments with spaces between them. The term mesh also includes woven and nonwoven fabrics.

[0069] The filaments may define interstices between the filaments, and the interstices may have a width of between 10 and 100 microns.Preferably, the filaments create capillary action in the interstices such that, in use, source liquid is drawn into the interstices thereby increasing the contact area between the susceptor element and the liquid.

[0070] The filaments may form a mesh having a size between 160 and 600 US Siemens mesh (+ / - 10%), i.e. between 160 and 600 filaments per inch (+ / - 10%). The width of the gaps may be between 35 microns and 140 microns, or between 25 microns and 75 microns. For example, the width of the gaps may be 40 microns or 63 microns. The percentage of open area of ​​the mesh, which is the ratio of the area of ​​the gaps to the total area of ​​the mesh, is preferably between 25% and 56%. The mesh may be formed using different types of weaves or mesh structures. Alternatively, the filaments consist of an array of filaments arranged parallel to each other.

[0071] The filaments may be formed by etching a sheet such as foil. This may be particularly advantageous when the heater assembly comprises an array of parallel filaments. If the heating element comprises a mesh or fabric of filaments, the filaments may be formed individually and woven together.

[0072] Preferably, the mesh is sintered. The filaments of the mesh may be sintered together. Advantageously, the sintered mesh produces electrical bonds between the filaments extending in different directions. In particular, where the mesh comprises one or more of a woven and a non-woven fabric, it is advantageous to sinter the mesh to produce electrical bonds between overlapping filaments.

[0073] As is well known in the art, a mesh may also be characterized by its ability to retain liquids.

[0074] The diameter of the filaments of the mesh may be between 8 and 100 microns, between 30 and 100 microns, between 8 and 50 microns, or between 8 and 39 microns. The filaments of the mesh may have a diameter of about 50 microns.

[0075] The filaments of the mesh may have any suitable cross-section. For example, the filaments may have a circular cross-section or may have a flat cross-section.

[0076] Advantageously, the mesh susceptor element may have a relative permeability between 1 and 40,000. When it is desired that most of the heating be dependent on eddy currents, a lower permeability material may be used, whereas when a hysteresis effect is desired, a higher permeability material may be used. Preferably, the material has a relative permeability between 500 and 40,000. This may provide efficient heating of the susceptor element.

[0077] The aerosol generating system comprises a cartridge. The cartridge may be connectable to an aerosol generating device.

[0078] The cartridge comprises a liquid reservoir. Preferably, the cartridge further comprises a susceptor element. In some preferred embodiments, wherein the cartridge comprises the susceptor element and the aerosol generating device comprises a cavity configured to receive a portion of the cartridge to couple the cartridge to the aerosol generating device, the susceptor element is arranged in the cartridge at a position received in the cavity of the aerosol generating device when the cartridge is coupled to the aerosol generating device.

[0079] In the case where the aerosol generating system comprises a tube, and the tube comprises a receptor element, the inductor coil may be arranged in the device so that when the tube is coupled to the aerosol generating device, the alternating magnetic field penetrates the tube, and in particular penetrates the receptor element in the tube. In the case where the aerosol generating device comprises a cavity for receiving the tube, the inductor coil may be arranged so that the alternating magnetic field penetrates the cavity. The inductor coil may be arranged at the cavity, in the cavity, or around the cavity. In some embodiments, the inductor coil may define the cavity. The inductor coil may be a tubular, spiral or helical coil that substantially defines the cavity. In other embodiments, the coil may be arranged at one side of the cavity.

[0080] In some embodiments where the susceptor element is planar and extends parallel to a plane, the inductor coil may be arranged to generate an alternating magnetic field penetrating the susceptor assembly in a direction substantially parallel to the plane.

[0081] In some embodiments where the susceptor element is planar and extends parallel to the plane, the inductor coil may be arranged to generate an alternating magnetic field penetrating the susceptor assembly in a direction substantially perpendicular to the plane.

[0082] A tubular or spiral inductor coil may define a susceptor element. A planar or flat inductor coil may be arranged at one side of the susceptor element. The planar or flat inductor coil may be circular, oval or rectangular. Preferably, the shape of the planar or flat inductor coil substantially corresponds to the shape of the susceptor element.

[0083] Where the susceptor element is substantially planar, extending parallel to a first plane, the inductor coil may be a flat inductor coil extending in a second plane substantially parallel to the first plane. In this arrangement, the inductor coil is arranged to generate an alternating magnetic field penetrating the susceptor assembly in a direction substantially perpendicular to the first plane.

[0084] In some preferred embodiments, the susceptor assembly includes a planar susceptor element, and the power circuit system includes a first flat inductor coil and a second flat inductor coil. The planar susceptor element extends in a first plane, the first inductor coil extends in a second plane parallel to the first plane, and the second inductor coil extends in a third plane parallel to the first plane and the second plane. The susceptor element is arranged between the first inductor coil and the second inductor coil. In this arrangement, the first inductor coil generates an alternating magnetic field that penetrates the susceptor element from a first side in a direction substantially perpendicular to the first plane, and the second inductor coil generates an alternating magnetic field that penetrates the susceptor assembly from a second side opposite to the first side in a direction substantially perpendicular to the first plane. Advantageously, this arrangement can provide efficient, uniform heating of the susceptor element. In these preferred embodiments, the induction heating assembly is configured so that the first inductor coil and the second inductor coil generate alternating magnetic fields of similar magnitude in opposite directions.

[0085] In some of these preferred embodiments, the first inductor coil and the second inductor coil may be electrically connected to form a single conductive path. In these embodiments, the first inductor coil may be wound in an opposite direction to the second inductor coil, so that the alternating magnetic fields generated by the first inductor coil and the second inductor coil are generated in opposite directions. Alternatively, the first inductor coil and the second inductor coil may be wound in the same direction, and the controller may be configured to supply an alternating current to each of the first inductor coil and the second inductor coil, so that the alternating magnetic fields generated by the first inductor coil and the second inductor coil are generated in opposite directions. The first inductor coil and the second inductor coil may be substantially identical. The first inductor coil and the second inductor coil may be substantially identical, but wound in opposite directions.

[0086] The cartridge comprises a liquid reservoir. The liquid reservoir is configured to hold a liquid aerosol-forming substrate. In particular, the liquid reservoir is configured to hold a liquid aerosol-forming substrate supplied to the susceptor element. The liquid reservoir may have any suitable shape and size, depending on the requirements of the aerosol generating system.

[0087] In certain embodiments, the liquid reservoir comprises a holding material for holding the liquid aerosol to form a matrix. In the case where the liquid reservoir comprises a plurality of parts, the holding material may be positioned in one or more parts in the parts, or may be positioned in all parts. The holding material may be a foam material, a sponge material or a fiber collection. The holding material may be formed by a polymer or a copolymer. In one embodiment, the holding material is a spinning polymer.

[0088] Where the cartridge comprises a wicking element and a retention material, the wicking element and the retention material may be formed of the same material or different materials. The retention material may be in fluid communication with the susceptor assembly. The retention material may contact the susceptor assembly. The retention material may be in fluid contact with the wicking element of the susceptor assembly. The retention material may contact the wicking element of the susceptor assembly.

[0089] In some embodiments, the cartridge includes a susceptor assembly. The susceptor assembly includes a susceptor element. The susceptor assembly may also include a liquid transport element. The liquid transport element may be in fluid communication with the susceptor element. The liquid transport element may be in fluid communication with a liquid reservoir. The liquid transport element may be arranged to transport a liquid aerosol-forming substrate from the liquid reservoir to the susceptor element. In particular, the liquid transport element may be arranged to transport a liquid aerosol-forming substrate from the liquid reservoir across a major surface of the susceptor element. The susceptor element may be fixed to the liquid transport element. The susceptor element may be integral with the liquid transport element. The provision of the liquid transport element may improve the wetting of the susceptor element and thereby increase aerosol generation of the system.

[0090] In some preferred embodiments, the liquid transport element is a wicking element. A wicking element may allow the susceptor element to be made of a material that does not inherently provide good wicking or wetting properties.

[0091] The susceptor assembly may comprise a plurality of susceptor elements. Where the susceptor assembly comprises a plurality of susceptor elements and a liquid transport element, each susceptor element may be arranged in fluid communication with the liquid transport element. The susceptor assembly may comprise a plurality of susceptor elements and a plurality of wicking elements.

[0092] In some preferred embodiments, the susceptor assembly includes a first susceptor element and a second susceptor element, the second susceptor element being spaced apart from the first susceptor element. The wicking element may be arranged in the space between the first susceptor element and the second susceptor element. In some particularly preferred embodiments, the first susceptor element, the second susceptor element and the wicking element are substantially planar, and the first susceptor element is arranged at a first side of the planar wicking element, and the second susceptor element is arranged at a second side of the planar wicking element opposite the first side.

[0093] The susceptor assembly may include a heating zone and at least one mounting area. The heating zone is an area of ​​the susceptor assembly that is configured to be heated to a temperature required to evaporate the aerosol-forming substrate when penetrated by a suitable alternating magnetic field. The at least one mounting area of ​​the susceptor assembly is an area configured to contact the housing of the cartridge or the susceptor element holder. In some preferred embodiments, the at least one mounting area extends into the liquid reservoir.

[0094] In the case where the liquid transfer component includes a wicking element, the wicking element may include a capillary material. Capillary material is a material that can transfer liquid from one end of the material to the other end by means of capillary action. The capillary material may have a fibrous or sponge-like structure. The capillary material preferably includes a capillary bundle. For example, the capillary material may include a plurality of fibers or threads or other fine-pore tubes. The fibers or threads may be generally aligned to transport the liquid aerosol-forming substrate toward the receptor element. In some embodiments, the capillary material may include a sponge-like or foam-like material. The structure of the capillary material may form a plurality of pores or tubules, and the liquid aerosol-forming substrate may be transported through the plurality of pores or tubules by capillary action. In the case where the receptor element includes a void or pore, the capillary material may extend into the void or pore in the receptor element. The receptor element may draw the liquid aerosol-forming substrate into the void or pore by capillary action.

[0095] The wicking element may include an electrically insulating material. The wicking element may include a thermally insulating material. The wicking element may include a hydrophilic material. The wicking element may include a lipophilic material. Advantageously, forming the wicking element from a hydrophilic or lipophilic material may facilitate the transport of the aerosol-forming substrate through the wicking element.

[0096] The wicking element may comprise a non-metallic material. Examples of suitable materials for the wicking element are sponges or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamed metals or plastic materials, for example fibrous materials made by spinning or extruding fibers, such as cellulose acetate, polyester or bonded polyolefins, polyethylene, polyester or polypropylene fibers, nylon fibers or ceramic fibers or glass fibers. Suitable materials for the wicking element may include cellulosic materials, such as cotton or rayon. Preferably, the wicking element may include rayon. The wicking element may be composed of rayon. When one or both of the susceptor elements include a conductive material deposited on the wicking element, a wicking element comprising a porous ceramic material may be particularly advantageous. A wicking element comprising a porous ceramic material may be an advantageous substrate for a manufacturing process associated with the deposition of a conductive material.

[0097] The cartridge may include an aerosol-forming substrate. As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds that can form an aerosol. The volatile compounds can be released by heating the aerosol-forming substrate. Preferably, the cartridge contains a liquid aerosol-forming substrate.

[0098] The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may include both liquid and solid components. The liquid aerosol-forming substrate may include nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt substrate. The liquid aerosol-forming substrate may include a plant-based material. The liquid aerosol-forming substrate may include tobacco. The liquid aerosol-forming substrate may include a tobacco-containing material containing volatile tobacco flavor compounds, which are released from the aerosol-forming substrate when heated. The liquid aerosol-forming substrate may include a homogenized tobacco material. The liquid aerosol-forming substrate may include a material that does not contain tobacco. The liquid aerosol-forming substrate may include a homogenized plant-based material.

[0099] The liquid aerosol-forming substrate may include one or more aerosol formers. An aerosol former is any suitable known compound or mixture of compounds that promotes the formation of a dense and stable aerosol in use and is substantially resistant to thermal degradation at the operating temperature of the system. Examples of suitable aerosol formers include glycerol and propylene glycol. Suitable aerosol formers are well known in the art and include, but are not limited to: polyols such as triethylene glycol, 1,3-butylene glycol and glycerol; esters of polyols such as mono-, di- or tri-acetates of glycerol; and aliphatic esters of mono-, di- or polycarboxylic acids such as dimethyl dodecanedioate and dimethyl tetradecanedioate. The liquid aerosol-forming substrate may include water, solvents, ethanol, plant extracts and natural or artificial flavoring agents.

[0100] The liquid aerosol-forming substrate may include nicotine and at least one aerosol former. The aerosol former may be glycerol or propylene glycol. The aerosol former may include both glycerol and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of between about 0.5% and about 10%, for example about 2%.

[0101] The cartridge may include an outer shell. The outer shell may be formed of a durable material. The outer shell may be formed of a liquid-impermeable material. The outer shell may be formed of a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET).

[0102] The susceptor assembly may be arranged in the outer housing. Where the cartridge comprises a susceptor element holder, the susceptor element holder may be arranged in the outer housing. In some embodiments, the susceptor element holder may be formed integrally with the outer housing. The susceptor element holder may be formed of the same material as the outer housing of the cartridge, or may be formed of a different material.

[0103] The outer housing may define a portion of the liquid reservoir. The outer housing may define the liquid reservoir. The outer housing and the liquid reservoir may be integrally formed. Alternatively, the liquid reservoir may be formed separately from the outer housing and arranged in the outer housing.

[0104] The cartridge may have a mouth end through which a user may inhale the generated aerosol.The cartridge may have a connection end configured to couple the cartridge to an aerosol generating device.

[0105] The barrel may define an air inlet. The air inlet may be arranged at or around the connection end of the barrel. The barrel may define a mouth end opening. A user may be able to inhale an aerosol generated from the barrel through the mouth end opening. The barrel may define a closed air flow path from the air inlet to the air outlet. The closed air flow path may extend from the air inlet through the susceptor element to the mouth end opening.

[0106] The closed gas flow passage may pass through the liquid reservoir.For example, the liquid reservoir may have an annular cross-section defining an internal passage, and the gas flow passage may extend through the internal passage of the liquid reservoir.

[0107] The aerosol generating device may include a housing. The housing may be elongated. The housing may include any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics or composite materials containing one or more of these materials, or thermoplastic materials suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK) and polyethylene. Preferably, the material is lightweight and non-brittle.

[0108] The aerosol generating device housing may define a cavity for receiving a portion of the cartridge. The aerosol generating device may comprise one or more air inlets. The one or more air inlets may enable ambient air to be drawn into the cavity.

[0109] The aerosol generating device may have a connecting end configured to connect the aerosol generating device to the cartridge. The connecting end may comprise a cavity for receiving the cartridge.

[0110] The aerosol generating device may have a distal end opposite the connection end.The distal end may include an electrical connector configured to connect the aerosol generating device to an electrical connector of an external energy source for charging the energy source of the aerosol generating device.

[0111] The aerosol generating system may be a handheld aerosol generating system configured to allow a user to inhale on a mouthpiece to draw an aerosol through a mouth end opening. The aerosol generating system may have dimensions comparable to a conventional cigar or cigarette. The aerosol generating system may have an overall length between about 30 mm and about 150 mm. The aerosol generating system may have an outer diameter between about 5 mm and about 30 mm.

[0112] The aerosol generating system may be configured to deliver nicotine, among other things, to a user.

[0113] A method of operating an aerosol generating device is also provided, the aerosol generating device comprising a power supply and an inductor coil, and being configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element. The method may include controlling at least one of a current and a voltage between the power supply and the inductor coil. The method may also include comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry susceptor threshold. The method may also include determining whether the susceptor element is supplied with the liquid aerosol-forming substrate based on the comparison.

[0114] In some embodiments, the method further comprises notifying a user when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0115] In some embodiments, the method further comprises preventing current from being supplied to the inductor coil from the power supply when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0116] The method may also include controlling at least one of a current and a voltage from the power source to the inductor coil such that between about 6 watts and about 12 watts of power is supplied to the inductor coil. In some embodiments, the current and the voltage from the power source to the inductor coil are controlled such that the power delivered to the inductor coil is between about 8 watts and about 10 watts.

[0117] In some preferred embodiments, the method further comprises determining an equivalent resistance or apparent resistance of the susceptor element. The equivalent resistance comprises the quotient of the voltage and current between the power source and the inductor coil. The apparent resistance of the susceptor element may be determined by subtracting the resistance of the coil from the equivalent resistance determined from the quotient of the voltage and current between the power source and the inductor coil.

[0118] In some of these preferred embodiments, comparing at least one of current and voltage to a dry receptor threshold is a comparison of an equivalent resistance to a dry receptor threshold.The dry receptor threshold may be at least 1.05 ohms, and optionally may be between about 1.05 ohms and 2.20 ohms.

[0119] In some embodiments, the method further comprises controlling at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent resistance or a target apparent resistance of the susceptor element. Optionally, the target equivalent resistance or the target apparent resistance of the susceptor element may be between about 0.25 ohms and about 1.7 ohms. The dry susceptor threshold may be at least 15% greater than the target equivalent resistance or the target apparent resistance of the susceptor element. Optionally, the dry susceptor threshold may be at least 20% greater than the target equivalent resistance or the target apparent resistance of the susceptor element, or 15% to 50% greater than the target equivalent resistance or the target apparent resistance of the susceptor element.

[0120] In some embodiments, the method further comprises determining an equivalent conductance or apparent conductance of the susceptor element. As described above, the equivalent conductance comprises the quotient of the current and the voltage between the power source and the inductor coil. The apparent conductance of the susceptor element can be determined by subtracting the conductance of the coil from the equivalent conductance determined from the quotient of the current and the voltage between the power source and the inductor coil.

[0121] In some of these embodiments, comparing at least one of the current and the voltage to the dry receptor threshold is comparing the equivalent conductance or apparent conductance of the receptor element to the dry receptor threshold. The dry receptor threshold may be no less than 0.95 Siemens, and optionally may be between about 0.70 Siemens and about 0.95 Siemens.

[0122] In some embodiments, the method further comprises controlling at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent conductance or a target apparent conductance of the susceptor element. Optionally, the target equivalent conductance or the target apparent conductance of the susceptor element is between about 0.60 Siemens and about 4.00 Siemens. The dry susceptor threshold may be at least 15% less than the target equivalent conductance or the target apparent conductance of the susceptor element. Optionally, the dry susceptor threshold may be at least 20% less than the target equivalent conductance or the target apparent conductance of the susceptor element, or about 15% to about 50% less than the target equivalent conductance or the target apparent conductance of the susceptor element.

[0123] In some preferred embodiments, the method further comprises measuring a voltage between the power supply and the inductor coil.

[0124] In some preferred embodiments, the method further comprises measuring a current between the power source and the inductor coil.

[0125] In some embodiments, the aerosol generating device further comprises a puff detector, and the method further comprises detecting, using the puff detector, when a user takes a puff on the aerosol generating device. In some of these embodiments, the method further comprises supplying a current and a voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate an aerosol when the puff detector detects that the user takes a puff on the aerosol generating device.

[0126] In some embodiments, the method further comprises, when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate, preventing current and voltage from being supplied to the inductor coil so as not to generate an alternating magnetic field to heat the susceptor element and generate an aerosol.

[0127] It will be appreciated that any features described herein with respect to one embodiment may also apply to other embodiments.Features described with respect to the power circuit may equally apply to an aerosol generating device comprising the power circuit or an aerosol generating system comprising the power circuit.

[0128] The invention is defined in the claims. However, a non-exhaustive list of non-limiting examples is provided below. Any one or more features of these examples may be combined with any one or more features of another example, embodiment or aspect described herein.

[0129] 1. A power supply circuit for an aerosol generating device, the aerosol generating device being configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the power supply circuit comprising:

[0130] an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element;

[0131] Power supply; and

[0132] A controller, wherein the controller is configured to:

[0133] controlling at least one of a current and a voltage between the power source and the inductor coil;

[0134] comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; and

[0135] Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

[0136] 2. The power circuit according to example 1, wherein the controller is further configured to notify a user when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0137] 3. A power supply circuit according to any of examples 1 or 2, wherein the controller is further configured to prevent current from being supplied from the power supply to the inductor coil when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0138] 4. The power supply circuit of any one of examples 1 to 3, wherein the controller is configured to control at least one of a current and a voltage from the power supply to the inductor coil such that between about 6 Watts and about 12 Watts of power is supplied to the inductor coil, and optionally about 8 Watts to about 10 Watts is supplied to the inductor coil.

[0139] 5. A power supply circuit according to any one of Examples 1 to 4, wherein the controller is further configured to determine an equivalent resistance, the equivalent resistance being the quotient of the voltage and the current, and wherein the comparison of at least one of the current and the voltage with the dry receptor threshold is a comparison of the equivalent resistance with the dry receptor threshold.

[0140] 6. The power circuit of example 5, wherein the dry susceptor threshold is at least 1.05 ohms, and optionally between about 1.05 ohms and 2.20 ohms.

[0141] 7. The power circuit of example 5 or example 6, wherein the controller is configured to control at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent resistance, and optionally wherein the target equivalent resistance is between about 0.25 ohms and about 1.7 ohms.

[0142] 8. The power circuit of example 7, wherein the dry susceptor threshold is an equivalent resistance at least 15% greater than the target equivalent resistance, optionally at least 20% greater than the target equivalent resistance, and optionally 15% to 50% greater than the target equivalent resistance.

[0143] 9. A power circuit according to any one of Examples 1 to 4, wherein the controller is further configured to determine an equivalent conductance, the equivalent conductance being the quotient of the current and the voltage, and wherein the comparison of at least one of the current and the voltage to a dry receptor threshold is a comparison of the equivalent conductance to the dry receptor threshold.

[0144] 10. The power circuit of example 9, wherein the dry susceptor threshold is no less than 0.95 Siemens, and optionally between about 0.70 Siemens and about 0.95 Siemens.

[0145] 11. The power circuit of example 9 or example 10, wherein the controller is configured to control at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent conductance, and optionally wherein the target equivalent conductance is between about 0.60 Siemens and about 4.00 Siemens.

[0146] 12. The power circuit of example 11, wherein the dry susceptor threshold is at least 15% less than the target equivalent conductance, optionally at least 20% less than the target equivalent conductance, and optionally about 15% to about 50% less than the target equivalent conductance.

[0147] 13. The power supply circuit of any one of examples 1 to 12, wherein the controller is further configured to measure a voltage between the power supply and the inductor coil.

[0148] 14. The power supply circuit of any one of examples 1 to 13, wherein the controller is further configured to measure a current between the power supply and the inductor coil.

[0149] 15. The power supply circuit according to any one of examples 1 to 14, wherein the power supply is a DC power supply.

[0150] 16. The power supply circuit according to example 15, further comprising a DC / AC converter arranged between the DC power supply and the inductor coil.

[0151] 17. The power supply circuit according to example 16, wherein the DC / AC converter comprises a capacitor.

[0152] 18. The power supply circuit of example 16 or example 17, wherein the DC / AC converter comprises an LC (inductor capacitor) load network.

[0153] 19. A power supply circuit according to Example 16, wherein the DC / AC converter includes a capacitor, wherein the DC / AC converter also includes an LC (inductor capacitor) load network, and wherein the LC load network includes the inductor coil and the capacitor, and optionally wherein the inductor coil is connected in series with the capacitor.

[0154] 20. The power supply circuit of any one of examples 16 to 19, wherein the DC / AC converter comprises a class E power amplifier.

[0155] 21. The power supply circuit of any one of Examples 16 to 19, wherein the DC / AC converter comprises a class D power amplifier.

[0156] 22. A power circuit according to any one of Examples 1 to 21, further comprising a puff detector configured to detect when a user puffs on the aerosol generating device.

[0157] 23. A power supply circuit according to Example 22, wherein the controller is further configured to supply the current and the voltage to the inductor coil to generate an alternating magnetic field to heat the sensor element and generate the aerosol when the puff detector detects that a user puffs on the aerosol generating device.

[0158] 24. A power supply circuit according to example 23, wherein the controller is further configured to prevent the current and the voltage from being supplied to the inductor coil to generate the alternating magnetic field to heat the susceptor element and generate the aerosol when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0159] 25. An aerosol generating device configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating device comprising a power supply circuit according to any one of examples 1 to 24.

[0160] 26. An aerosol generating device configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating device being connectable to a cartridge comprising the susceptor element, and comprising a power supply circuit comprising:

[0161] an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element;

[0162] Power supply; and

[0163] A controller, wherein the controller is configured to:

[0164] controlling at least one of a current and a voltage between the power source and the inductor coil;

[0165] comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; and

[0166] Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

[0167] 27. An aerosol generating device according to example 25 or example 26, further comprising a cavity configured to receive a portion of a cartridge to couple the cartridge to the aerosol generating device.

[0168] 28. An aerosol generating device according to example 27, wherein the inductor coil is arranged at or around the cavity.

[0169] 29. An aerosol generating device according to example 27 or example 28, wherein the inductor coil is arranged to generate an alternating magnetic field in the cavity.

[0170] 30. An aerosol generating device according to any one of examples 27 to 29, wherein the inductor coil defines the cavity.

[0171] 31. An aerosol generating system comprising:

[0172] a cartridge comprising a susceptor element and a liquid aerosol-forming substrate supplied to the susceptor element; and

[0173] An aerosol generating device according to any one of examples 25 to 30.

[0174] 32. An aerosol generating system comprising:

[0175] A cartridge, comprising:

[0176] a receptor element; and

[0177] a liquid aerosol-forming substrate supplied to the susceptor element; and

[0178] an aerosol generating device, which is coupleable to the cartridge and is configured to heat the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating device comprising a power circuit comprising:

[0179] an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element;

[0180] Power supply; and

[0181] A controller, wherein the controller is configured to:

[0182] controlling at least one of a current and a voltage between the power source and the inductor coil;

[0183] comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; and

[0184] Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

[0185] 33. An aerosol generating system according to example 31 or example 32, wherein the cartridge further comprises a liquid transport element arranged to supply the liquid aerosol-forming substrate to the susceptor element.

[0186] 34. An aerosol generating system according to any one of examples 31 to 33, wherein the susceptor element is a mesh susceptor element.

[0187] 35. An aerosol generating system according to any one of Examples 31 to 34, wherein the aerosol generating device includes a cavity configured to receive a portion of a tube to connect the tube to the aerosol generating device, and wherein when the tube is connected to the aerosol generating device, the sensor element is arranged in the tube in a position received in the cavity of the aerosol generating device.

[0188] 36. A method of operating an aerosol generating device, the aerosol generating device comprising a power supply and an inductor coil, and configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the method comprising:

[0189] controlling at least one of a current and a voltage between the power source and the inductor coil;

[0190] comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; and

[0191] Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

[0192] 37. The method of example 36, further comprising notifying a user upon determining that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0193] 38. The method according to any of examples 36 or 37, further comprising preventing the supply of current from the power supply to the inductor coil when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0194] 39. The method of any one of Examples 36 to 38, further comprising controlling at least one of a current and a voltage from the power supply to the inductor coil such that between about 6 Watts and about 12 Watts of power is supplied to the inductor coil, and optionally between about 8 Watts and about 10 Watts is supplied to the inductor coil.

[0195] 40. The method of any one of Examples 36 to 39, further comprising determining an equivalent resistance, the equivalent resistance being a quotient of the voltage and the current, and wherein comparing at least one of the current and the voltage to the dry receptor threshold is a comparison of the equivalent resistance to the dry receptor threshold.

[0196] 41. The method of example 41, wherein the dry susceptor threshold is at least 1.05 ohms, and optionally between about 1.05 ohms and 2.20 ohms.

[0197] 42. The method of example 41 or example 42, further comprising controlling at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent resistance, and optionally wherein the target equivalent resistance is between about 0.25 ohms and about 1.7 ohms.

[0198] 43. The method of example 42, wherein the dry receptor threshold is an equivalent resistance at least 15% greater than the target equivalent resistance, optionally at least 20% greater than the target equivalent resistance, and optionally 15% to 50% greater than the target equivalent resistance.

[0199] 44. The method of any one of Examples 36 to 39, further comprising determining an equivalent conductance, the equivalent conductance being the quotient of the current and the voltage, and wherein the comparison of at least one of the current and the voltage to a dry receptor threshold is a comparison of the equivalent conductance to the dry receptor threshold.

[0200] 45. The method of example 44, wherein the dry receptor threshold is no less than 0.95 Siemens, and optionally between about 0.70 Siemens and about 0.95 Siemens.

[0201] 46. ​​The method of example 44 or example 45, further comprising controlling at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent conductance, and optionally wherein the target equivalent conductance is between about 0.60 Siemens and about 4.00 Siemens.

[0202] 47. The method of example 46, wherein the dry receptor threshold is at least 15% less than the target equivalent conductance, optionally at least 20% less than the target equivalent conductance, and optionally about 15% to about 50% less than the target equivalent conductance.

[0203] 48. The method of any one of Examples 36 to 47, further comprising measuring a voltage between the power source and the inductor coil.

[0204] 49. The method of any one of Examples 36 to 48, further comprising measuring a current between the power source and the inductor coil.

[0205] 50. A method according to any one of Examples 36 to 49, wherein the aerosol generating device further comprises a puff detector, and the method further comprises using the puff detector to detect when a user puffs on the aerosol generating device.

[0206] 51. The method according to Example 50 further includes supplying the current and the voltage to the inductor coil to generate the alternating magnetic field to heat the sensor element and generate the aerosol when the puff detector detects that the user puffs on the aerosol generating device.

[0207] 52. The method of example 51, further comprising preventing the current and the voltage from being supplied to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate the aerosol when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

[0208] Several examples will now be further described with reference to the accompanying drawings, in which:

[0209] Figure 1a shows a schematic diagram of an aerosol generating system according to an example of the present disclosure, the aerosol generating system comprising an aerosol generating device and a cartridge;

[0210] Figure 1b Shows Figure 1a Schematic diagram of an aerosol generating system rotated 90 degrees around a central longitudinal axis of the aerosol generating system;

[0211] Figure 2a shows a schematic diagram of a cartridge for an aerosol generating system according to an example of the present disclosure, wherein the cartridge is in a storage configuration;

[0212] Figure 2b Shows Figure 2a A schematic diagram of a cylinder rotated 90 degrees around the central longitudinal axis of the cylinder;

[0213] Figure 2c Shows Figure 2a A schematic diagram of a cartridge of , wherein the cartridge is in a use configuration;

[0214] Figure 3a Shows Figure 2a , 2b and a side view of the sensor assembly of the cartridge of 2c;

[0215] Figure 3b Shows Figure 3a A perspective view of the sensor assembly;

[0216] Figure 3c Shows Figure 3a A plan view of the receptor assembly;

[0217] Figure 4 Shows Figure 1a and 1b A schematic block diagram of a power supply circuit of an aerosol generating device;

[0218] Figure 5 Shows Figure 4 A schematic circuit diagram of a heater module of a power supply circuit;

[0219] Figure 6 The operation according to the embodiment of the present disclosure is shown Figure 4 A flowchart of a simplified method of a power supply circuit; and

[0220] Figure 7 The operation according to another embodiment of the present disclosure is shown Figure 4 A flow chart of a simplified method of a power supply circuit.

[0221] Figure 1a and 1b A schematic diagram of an aerosol generating system according to an example of the present disclosure is shown. The aerosol generating system comprises a cartridge 10 received in an aerosol generating device 60 in a use configuration. The aerosol generating system is portable and has a size comparable to a conventional cigar or cigarette.

[0222] Figure 2a , 2b and 2c shows Figure 1a and 1b Schematic diagram of a cartridge 10. The cartridge 10 has an oral end and a connecting end opposite to the oral end. As described in detail below, the connecting end is configured to connect the cartridge 10 to an aerosol generating device.

[0223] The barrel 10 includes an outer shell 36 formed of a moldable plastic material such as polypropylene. The outer shell 36 defines an orifice opening 38 at the orifice end of the barrel 10. The outer width of the outer shell 36 is greater at the orifice end of the barrel 10 than at the connection end, and the orifice end and the connection end are connected by a shoulder 37. This arrangement enables the connection end of the barrel 10 to be received in the cavity 64 of the aerosol generating device 60, wherein the shoulder 37 positions the barrel 10 in the correct position in the device. This also enables the orifice end of the barrel 10 to remain outside the aerosol generating device 60, wherein the orifice end matches the external shape of the aerosol generating device 60.

[0224] The cartridge 10 also includes a susceptor assembly 12 mounted in a susceptor element holder 14 .

[0225] The susceptor assembly 12 is described in more detail below.

[0226] The susceptor element holder 14 includes a tubular body formed of a moldable plastic material such as polypropylene. The tubular body of the susceptor element holder 14 includes a sidewall defining an internal passageway 26 having an open end and a central longitudinal axis. A pair of openings 28 extend through the sidewall at opposite sides of the tubular susceptor element holder 14. The openings 28 are centrally located along the length of the susceptor element holder 14. The susceptor element holder 14 also includes a base 30 that partially closes one end of the internal passageway 26. The base 30 includes a plurality of air inlets 32 that enable air to be drawn into the internal passageway 26 through the partially closed end.

[0227] The outer housing 36 forms a first portion of the cartridge 10, and the susceptor assembly 12 and the susceptor element holder 14 form a second portion of the cartridge 10. The second portion of the cartridge may be positioned relative to the first portion of the cartridge such as Figure 2a and 2b The storage configuration shown in Figure 2c The susceptor assembly 12 and susceptor element holder 14 are positioned towards the connection end of the cartridge 10 .

[0228] A liquid reservoir 40 is defined in the cartridge 10 for holding a liquid aerosol-forming substrate 42. The liquid reservoir 40 is divided into two parts: a first part 44 and a second part 46. The first part 44 is located towards the mouth end of the outer shell 36 and includes an annular space defined by the outer shell 36. The annular space has an internal passage 48 extending between the mouth end opening 38 and the open end of the internal passage 26 of the susceptor element holder 14. The second part 46 of the liquid reservoir 40 is located towards the connection end of the outer shell 36 and includes an annular space defined between the inner surface of the outer shell 36 and the outer surface of the susceptor element holder 14. The base 20 of the tubular susceptor element holder 14 is provided with an annular ribbed elastomeric seal 50 extending between the outer surface of the tubular susceptor element 14 and the inner surface of the outer shell 36. The seal 50 provides an airtight seal between the susceptor element holder 14 and the outer shell 36.

[0229] Figure 3a , 3b The susceptor assembly 12 is shown in more detail in FIGS. 3 and 3c. The susceptor assembly 12 is planar, thin, and generally rectangular. The susceptor assembly 12 includes three layers: a first susceptor element 16, a second susceptor element 18, and a wicking element 20 disposed between the first susceptor element 16 and the second susceptor element 18. The first susceptor element 16 and the second susceptor element 18 are substantially identical and include a sintered mesh formed of SAE 410 stainless steel, ferritic stainless steel wire. The wicking element 20 includes a porous body of rayon.

[0230] The first susceptor element 16 and the second susceptor element 18 and the wicking element 20 each form a substantially rectangular sheet. The wicking element 20 is arranged between the first susceptor element 16 and the second susceptor element 18, wherein the first susceptor element 16 and the second susceptor element 18 are arranged opposite to each other and centrally relative to the wicking element 20. The wicking element 20 has a length substantially the same as the length of the first susceptor element 16 and the second susceptor element 18, and a width greater than the width of the first susceptor element 16 and the second susceptor element 18. Two outer edge portions 22 of the wicking element 20 are not covered by the first susceptor element 16 and the second susceptor element 18. Therefore, the susceptor assembly 12 includes a pair of mounting areas 22 formed by the uncovered edge portions of the wicking element 20. The susceptor assembly 12 also includes a heating zone 24 formed by a central area including the first susceptor element 16 and the second susceptor element 18 and a central portion of the wicking element 20 between the first susceptor element 16 and the second susceptor element 18.

[0231] The wicking element 20 is configured to supply the liquid aerosol-forming substrate from the exposed outer edge portion 22 to the first susceptor element 16 and the second susceptor element 18. The heating zone 24 is configured to be heated by the penetration of the alternating magnetic field for evaporating the aerosol-forming substrate supplied by the wicking element 20 to the susceptor elements 16, 18.

[0232] The pair of mounting regions 22 are configured to extend into the liquid reservoir 40 of the cartridge 10 to deliver the liquid aerosol-forming substrate from the reservoir 40 to the first susceptor element 16 and the second susceptor element 18. The pair of mounting regions 22 are also configured to contact the susceptor element holder 14 so that the susceptor element holder 14 can support the susceptor assembly 12 in a suitable position in the cartridge 10.

[0233] The heating zone 24 of the susceptor assembly is disposed entirely within the internal passage 26 of the susceptor element holder 14, and each of the mounting areas 22 extends through one of the openings 28 in the side wall of the susceptor element holder 14. The openings 28 in the side wall of the susceptor element holder 14 are sized to receive the susceptor assembly 12 with a friction fit such that the susceptor assembly is secured in the susceptor element holder 14. The susceptor assembly 12 extends substantially in a plane parallel to the central longitudinal axis of the susceptor element holder 14.

[0234] The susceptor element holder 14 also includes a pair of piercing elements 34 extending from the outer surface of the side wall toward an open end of the susceptor element holder 14, the open end being opposite the end partially closed by the base 30. The opening 28 in the side wall of the susceptor element holder 14 is arranged around the circumference of the side wall between the piercing elements 34, such that the piercing elements 34 are offset from the opening 28 by about 90 degrees around the circumference of the side wall of the tubular susceptor element. Each of the piercing elements 34 includes a pointed tip facing in the direction of the open end of the susceptor element holder 14.

[0235] An air passage is formed through the cartridge 10 by the internal passage 26 of the susceptor element holder 14 and the internal passage 48 through the first portion 44 of the liquid reservoir 40. The air passage extends from the air inlet 32 ​​in the base 30 of the susceptor element holder 14, through the internal passage 26 of the susceptor element holder 14, and through the internal passage 48 of the first portion 44 of the liquid reservoir 40 to the mouth end opening 38. The air passage enables air to be drawn from the connection end through the cartridge 10 to the mouth end.

[0236] When the cartridge is in the storage configuration, Figure 2a and 2b , the base 30 of the susceptor element holder 14 extends out of the outer housing 36. The first portion 44 and the second portion 46 of the liquid reservoir 40 are fluidly isolated from each other by an aluminum foil seal 52, and the piercing element 34 of the susceptor element holder 14 is spaced apart from the seal 52 in the direction of the connection end of the cartridge 10. In this configuration, the liquid aerosol-forming substrate 42 is held in the first portion 44 of the liquid reservoir 40 and is isolated from the second portion 46 of the liquid reservoir 40 and the susceptor assembly 12 by the seal 52.

[0237] In the usage configuration, such as Figure 2c As shown in FIG, the susceptor element holder 14 and the susceptor assembly 12 are pushed into the outer housing 36 toward the mouth end. As the susceptor element holder 14 is pushed toward the mouth end of the outer housing 36, the seal 52 at the base 30 of the susceptor element holder 14 slides on the inner surface of the outer housing 36 to establish a liquid-tight seal between the inner surface of the outer housing 36 and the outer surface of the tubular susceptor element holder body. As the susceptor element holder 14 moves toward the mouth end, the piercing element 34 contacts and pierces the seal 52 to allow fluid communication between the first portion 44 of the liquid reservoir 40 and the second portion 46 of the liquid reservoir 40. The liquid aerosol-forming substrate 42 in the first portion 44 of the liquid reservoir 40 is released into the second portion 46 of the liquid reservoir 40, and the susceptor assembly 12 is exposed to the liquid aerosol-forming substrate 42.

[0238] In the use configuration, the mounting area 22 of the wicking element 20 extending into the second portion 46 of the liquid reservoir 40 is able to draw the liquid aerosol-forming substrate 42 from the second portion 46 of the liquid reservoir 40 to the first susceptor element 16 and the second susceptor element 18. Thus, in the use configuration, the first and second susceptor elements are supplied with the liquid aerosol-forming substrate 42 and the cartridge 10 is ready for generating an aerosol by heating the liquid aerosol-forming substrate 42.

[0239] like Figure 1a and 1b As shown in , the aerosol generating device 60 comprises a generally cylindrical housing 62 having a connection end and a distal end opposite the connection end. A cavity 64 for receiving the connection end of the cartridge 10 is located at the connection end of the device 60, and an air inlet 65 is provided through the outer housing 62 at the base of the cavity 64 to enable ambient air to be drawn into the cavity 64 at the base.

[0240] The device 60 also includes a power supply circuit 66. The power supply circuit 66 includes an inductor coil 68, a controller 70, and a power supply 72. The power supply 72 includes a rechargeable lithium iron phosphate battery having a DC supply voltage of 3.2 volts, which is recharged via an electrical connector (not shown) at the distal end of the device. The controller 70 is connected to the power supply 72 and to the inductor coil 68 so that the controller 70 controls the power supply to the inductor coil 68. The power supply circuit 66 is configured to supply an alternating current to the inductor coil 68.

[0241] The inductor coil 68 includes a solenoid coil that defines the cavity 64. When the cartridge 10 is received in the cavity 64, the first susceptor element 16 and the second susceptor element 18 are also defined by the inductor coil 68.

[0242] The inductor coil 68 is configured such that when the cartridge 10 is received in the cavity 64 , when an alternating current is supplied to the inductor coil 68 , the inductor coil 68 generates an alternating magnetic field in the cavity 64 that penetrates the first susceptor element 16 and the second susceptor element 18 .

[0243] The aerosol generating device 60 further comprises a flux concentrator element 69. The flux concentrator element 69 has a larger radius than the inductor coil 68 and therefore partially surrounds the inductor coil 68. The flux concentrator element 69 is configured to reduce stray power losses from the generated magnetic field.

[0244] In operation, Figure 1bAs shown by the arrows in FIG. 1 , when a user draws on the mouth end opening 38 of the cartridge 10, ambient air is drawn into the base of the cavity 64 through the air inlet 65 and into the cartridge 10 through the air inlet 32 ​​in the base 30 of the cartridge 10. Ambient air flows from the base 30 through the cartridge 10 to the mouth end opening 38, through the air passageway, and across the susceptor assembly 12.

[0245] When the system is activated, the controller 70 controls the supply of power from the power supply 72 to the inductor coil 68. The controller 72 includes a puff detector in the form of an airflow sensor (not shown), and when a user puffing on the cartridge 10 is detected by the puff detector, the controller 72 supplies power to the inductor coil 68.

[0246] When the system is activated, an alternating current is established in the inductor coil 68, which generates an alternating magnetic field in the cavity 64 that penetrates the first susceptor element 16 and the second susceptor element 18, causing the first susceptor element 16 and the second susceptor element 18 to heat up. The liquid aerosol-forming substrate in the second portion 44 of the liquid reservoir 40 is supplied to the first susceptor element 16 and the second susceptor element 18 by the wicking element 20. The liquid aerosol-forming substrate supplied to the first susceptor element 16 and the second susceptor element 18 is heated, and volatile compounds from the heated aerosol-forming substrate are released into the air passage of the cartridge 10, and the volatile compounds cool to form an aerosol. The aerosol is entrained in the air drawn through the air passage of the cartridge 10 and is drawn out of the cartridge 10 at the mouth end opening 38 for inhalation by the user.

[0247] Figure 4 The present invention is used to illustrate the embodiment of the present invention. Figure 1a and 1b Schematic block diagram of a power supply circuit 66 of an aerosol generating device 60. The power supply circuit 66 includes a microcontroller 70, a battery 72, and a heater engine or heater module 74 including an inductor coil 68. In the present example, the microcontroller 70 is mounted on the same printed circuit board (not shown) along with other electronic components and the heater module 74, but it should be understood that the heater module 74 may be provided on a separate dedicated printed circuit board.

[0248] When Figure 1a and Figure 1bWhen the cartridge 10 shown in FIG. 1 is coupled to the aerosol generating device 60, the microcontroller 70 is configured to control the heater module 74, and in particular to control the power delivered to the induction coil 68, which is inductively coupled to the first susceptor element 16 and the second susceptor element 18 in the cartridge 10. The microcontroller 70 is also configured to control the general operation of the aerosol generating device 60, and is connected to various other electronic components (not shown) of the aerosol generating device 60 to enable it to perform this function. For example, such other electronic components may include sensors, user interfaces such as LEDs or LCD screens for displaying information to a user, and switches for activating the aerosol generating device 60, devices for providing a data connection with an external device, and charging circuitry for recharging the battery 72.

[0249] In this example, a single microcontroller 70 is provided to control all features of the aerosol generating device 60. However, it will be appreciated that in some embodiments, several microcontrollers may be provided, each controlling a different feature of the aerosol generating device 60. For example, a first microcontroller may be provided to control a heater module, and a second microcontroller may be provided to control the general operation of the aerosol generating device. In this example, the first microcontroller may be part of the heater module, and may be dedicated to controlling the power delivered to the induction coil of the heater module. An advantage of the heater module having its own microcontroller is that it helps make the heater module reusable in different devices, because it can be programmed with its own firmware for controlling the heating process, and there is no need to include firmware related to heating in other components. This can make the heater module a stand-alone unit or module that can be integrated into a variety of different devices.

[0250] As referenced below Figure 5 As will be discussed in greater detail, the heater module 74 includes drive circuitry that drives the induction coil 68 to heat the first susceptor element 16 and the second susceptor element 18 in the cartridge 10. Figure 4 The heater module 74 also includes a DC / AC voltage converter ( Figure 4 ), the DC / AC voltage converter is connected to the drive circuit system and converts the DC voltage fed to the drive circuit system into an AC voltage so as to generate an alternating current in the induction coil 68, which in turn causes the induction coil 68 to generate a changing or alternating magnetic field. In this example, the induction coil 68 is part of the DC / AC voltage converter. This arrangement helps to reduce the number of electrical components required. However, it should be understood that the induction coil 68 can be separated from the DC / AC voltage converter, although this may require additional components in order to generate the AC voltage. The DC / AC voltage converter also includes a matching network ( Figure 4), the matching network is configured to operate under low ohmic loads and helps match the output impedance of the DC / AC converter to the load represented by the resistive losses in the induction coil and the apparent resistance of the susceptor elements 16, 18.

[0251] The power supply circuit 66 also includes a DC / DC voltage converter 76 configured to convert a DC power supply voltage V supply , and outputs a constant voltage of 2.95 volts at the voltage converter output 77. The voltage converter output 77 is connected to the heater module 74 and provides a voltage input to the heater module 74. Therefore, the output voltage from the DC / DC voltage converter 76 constitutes the heater module input voltage Vin. The heater module input voltage Vin is used to power the heater module 74. This heater module input voltage is selected based on the specific components of the heater module to provide a predetermined heating performance. It should be understood that different heater module input voltages can be used to provide different heating performances, and the DC / DC voltage converter 76 can be configured to output different voltages. However, once the heater module input voltage Vin has been set, a significant change in the heater module input voltage Vin will change the power delivered to the induction coil and may cause undesirable changes in heating performance. In addition, multiple component parameters of the heater module 74 are sensitive to the input voltage, and changing the heater module input voltage Vin may cause unstable conditions. Therefore, the DC / DC voltage converter 76 helps to reduce variability and improve stability by providing a constant heater module input voltage Vin. For clarity, the DC / DC voltage converter 76 has been shown as a separate component in this example, but it may be part of the heater module 74 .

[0252] Figure 1a and 1b The aerosol generating device 60 Figure 4 The power supply circuit 66 converts the DC supply voltage of the 3.2 volt lithium iron phosphate battery 72 into a constant heater module input voltage of 2.95 volts. In this case, the DC / DC voltage converter 76 helps maintain the constant heater module input voltage Vin, but in the absence of the DC / DC voltage converter 76, the heater module 74 can operate relatively normally with the 3.2 volt power supply from the lithium iron phosphate battery 72 because there is not much difference between this supply voltage and the heater module input voltage of 2.95 volts. However, it should be understood that the heater module 74 can be used in different aerosol generating devices using batteries with different battery chemistries. For example, Figure 1a and 1bThe aerosol generating device 60 may use a lithium nickel manganese cobalt oxide battery having a DC supply voltage of 4.2 volts. In this case, the DC / DC voltage converter 76 allows the heater module 74 to perform in a manner similar to the way the heater module 74 performs without the DC / DC voltage converter 76 by converting this higher DC supply voltage to 2.95 volts using the lithium iron phosphate battery 72 to supply voltage directly. In fact, the DC / DC voltage converter 76 is configured to accept a range of DC supply voltages and output a constant heater module input voltage. Therefore, the DC / DC voltage converter 76 of the heater module 74 allows the use of different types of batteries having a range of DC supply voltages.

[0253] Figure 5 Shown in more detail Figure 4 A portion of the power supply circuit 66, specifically, Figure 4 A heater module 74 is provided. Figure 5 The circuit is derived from Figure 4 The output voltage 77 of the DC / DC voltage converter 76 is Figure 5 The heater module 74 is powered by a heater module input voltage Vin received at point X in the circuit. The heater module 74 includes a transistor switch Q1 and a first inductor L1, which act as a drive circuit system for driving the inductive coil 68 and the DC / AC voltage converter. The transistor switch Q1 includes a field effect transistor (FET), such as a metal oxide semiconductor field effect transistor (MOSFET), and the first inductor L1 includes an RF choke. The heater module input voltage Vin is fed to the transistor switch Q1 via a resistor R3 (discussed in more detail below) and the first inductor L1. The first inductor L1 helps to reduce the entry of RF into the circuit that may be present at the input X. The gate G of the transistor switch Q1 is connected to Figure 4 The microcontroller 70 of the embodiment of the present invention receives a switching signal from the microcontroller 70 to turn on and off the transistor switch Q1. The switching signal is a square wave with a duty cycle of substantially 50%.

[0254] The heater module 74 also includes a first capacitor C1 connected in series with a second inductor L2 corresponding to the induction coil 68. The second capacitor C2 is connected between the drain D of the transistor switch Q1 and the electrical ground and acts as a shunt capacitor. The first capacitor C1, the second inductor L2 and the second capacitor C2 define a DC / AC voltage converter for converting the switching signal transmitted to the transistor switch Q1 into an AC voltage across an equivalent resistor R4. The equivalent resistor R4 is equivalent to the ohmic resistance R of the second inductor L2 connected in series with the apparent ohmic resistance Ra of the sensor elements 16, 18. coil The resistor R4 is Figure 51 is shown in dashed lines to indicate that it is the equivalent resistance of the second inductor L2 and the susceptor elements 16, 18 rather than the equivalent resistance of the actual resistor in the circuit.

[0255] The first inductor L1, the transistor switch Q1, the first capacitor C1, the second inductor L2 and the second capacitor C2 together form a class E power amplifier. The general operating principle of a class E power amplifier is known and described in detail in the article "Class E RF Power Amplifier" (Nathan O. Sokal, published in the bimonthly QEX, January / February 1001 edition, pages 9-20, American Radio Relay League (ARRL), Newington, Connecticut, USA), and is therefore not discussed further here.

[0256] It has been found that using a class E amplifier to power the second inductor L2 is efficient. This is because, due to the configuration of the circuit, the current through the transistor switch Q1 does not occur at the same time as the voltage exists across the transistor switch Q1. Therefore, substantially no energy is dissipated in the transistor switch Q1, and substantially all power is fed to the load equivalent resistor R4. In addition, the first capacitor C1 and the second inductor L2 form a series resonant circuit that is tuned to the switching frequency of the switching signal. The first capacitor C1 and the second inductor L2 act as a bandpass filter, which allows the AC voltage signal to be transmitted to the load equivalent resistor R4 only at the required operating frequency of the second inductor L2. This means that power is transmitted to the load equivalent resistor R4 only at the switching frequency of the switching signal, and any harmonic frequencies are significantly suppressed, which helps to further improve efficiency.

[0257] In addition, the second inductor L2 and the capacitors C1 and C2 form an LC load network or matching network that is configured to operate under a low ohmic load and helps match the output impedance of the DC / AC converter to the load equivalent resistance R4. In particular, the capacitors C1 and C2 are tuned to reduce the ohmic load of the second inductor L2 relative to the susceptor elements 16, 18 so that more heat is dissipated in the susceptor elements 16, 18 compared to the inductor L2, which is desirable for heating the aerosol-forming substrate.

[0258] Compared to other power supply circuits for an aerosol generating device, the heater module 74 comprises relatively few components, so the printed circuit board area required to mount these components can be kept small, which helps to reduce the overall size of the aerosol generating device 60. In addition, by using the second inductor L2 in the DC / AC conversion, the number of components is further reduced.

[0259] During operation, the second inductor L2 generates an alternating magnetic field that induces eddy currents in the susceptor elements 16, 18 of the cartridge 10, thereby heating the susceptor elements 16, 18. When the susceptor elements 16, 18 are heated during operation, the liquid aerosol-forming substrate supplied from the liquid reservoir 40 to the susceptor elements 16, 18 via the liquid transport element 20 evaporates.

[0260] The present inventors have realised that whilst liquid aerosol-forming substrate is being supplied to the susceptor elements 16, 18 and the liquid aerosol-forming substrate is evaporating, the apparent resistance Ra of the susceptor elements 16, 18 remains substantially constant. However, if the supply of liquid aerosol-forming substrate to the susceptor elements 16, 18 is reduced or stopped, then as the liquid reservoir is depleted, the apparent resistance Ra of the susceptor elements 16, 18 increases, causing the equivalent resistance R4 to increase and the DC current IDC drawn by the heater module 74 at a constant voltage to decrease.

[0261] Figure 5 The circuit also includes two sensor circuits for determining an equivalent resistance Re or an equivalent conductance G4 of the equivalent resistance R4: a current sensor circuit 80 and a voltage sensor circuit 82.

[0262] The current sensor circuit 80 includes a current sensor in the form of a resistor R3 having a known value. The resistor R3 is connected in series between point X (receiving the heater module input voltage Vin) and the first inductor L1. Therefore, during operation, the DC current IDC through the resistor R3 is substantially the same as the current drawn by the heater module 74. As discussed above, Figure 5 The circuit is derived from Figure 4 The DC current IDC through resistor R3 is equal to the DC current supplied by the DC / DC voltage converter 76. Resistor R3 has a suitably low resistance value to help reduce resistive losses.

[0263] The current sensor circuit 80 also includes a differential amplifier 84 having two inputs 84a and 84b connected at either side of the resistor R3 and thus receiving a voltage signal from either side of the resistor R3. The differential amplifier 84 has an output 84c, the voltage of which is proportional to the difference between the voltages received at its inputs 84a and 84b, i.e., the voltage drop VR3 across the resistor R3. The output 84c of the differential amplifier 84 is connected to an analog-to-digital converter (ADC) input of a microcontroller (MCU), which in this embodiment is Figure 4The microcontroller 70 is configured to determine the voltage drop VR3 across the resistor R3 based on the signal received from the output 84c of the differential amplifier 84. Since the resistor R3 has a known value, the DC current IDC fed to the heater module 74 through the resistor R3 can be determined by the microcontroller 70 by applying Ohm's law as shown in equation (1):

[0264] I DC = V R3 / R3 (1)

[0265] The voltage sensor circuit 82 includes a Figure 5 A first resistor R1 and a second resistor R2 are connected between a point X in the circuit and electrical ground, where the heater module input voltage Vin is received at point X. The resistors R1 and R2 form a voltage divider or potential divider and have equal resistance values ​​so that the voltage at a point Y between the resistors R1 and R2 is equal to half of the heater module input voltage Vin. Point Y is connected to a microcontroller (MCU), i.e. Figure 4 The analog-to-digital converter (ADC) input of the microcontroller 70 is connected to the microcontroller 70 to provide a voltage signal corresponding to the voltage at point Y to the microcontroller 70. This allows the microcontroller 70 to determine the heater module input voltage Vin by multiplying the voltage signal received from point Y by two. It should be understood that other resistance values ​​can be used for resistors R1 and R2, but this will involve corresponding adjustments to the voltage calculations performed by the microcontroller. Resistors R1 and R2 have relatively high resistance values ​​to reduce the current drawn through the divider.

[0266] The voltage sensor circuit 82 is optional because, as described above, the heater module input voltage Vin corresponds to the voltage from Figure 4 The constant voltage output of the DC / DC voltage converter 76 in the microcontroller 70 is used. Therefore, the heater module input voltage Vin is known and constant, and can therefore be stored as a value in the memory of the microcontroller 70. However, the provision of the voltage sensor circuit 82 allows the heater module input voltage Vin to be checked to confirm that it is the same as the voltage stored in the memory. The provision of the voltage sensor circuit 82 negates the need to store the heater module input voltage Vin in memory, thereby simplifying the programming of the microcontroller 70.

[0267] As described above, it has been found that the class E power amplifier is an efficient means for delivering power to the load equivalent resistance R4. Therefore, the DC current IDC through the resistor R3 indicates the current being supplied to the load equivalent resistance R4. In addition, the resistance value of the resistor R3 is relatively small, and therefore the voltage drop across the resistor R3 can be substantially ignored. Therefore, the value of the load equivalent resistance R4 can be determined by the microcontroller 70 by applying Ohm's law as shown in equation (2):

[0268] R4 = V in / I DC (2)

[0269] The above equation (2) can be rewritten as shown in the following equation (3) to obtain the equivalent conductance G4 of the load equivalent resistance R4:

[0270] G4 = I DC / V in (3)

[0271] The equivalent conductance G4 is the reciprocal of the equivalent resistance R4. The advantage of determining the equivalent conductance G4 according to equation (3) is that when the voltage Vin is constant, the conductance indicates or is directly related to the DC current IDC, which is because Vin is determined by Figure 4 The DC current IDC is provided by the DC / DC voltage converter 76. Therefore, the current supplied by the DC / DC voltage converter and measured by the current sensor circuit 80 provides a direct indication of the equivalent conductance G4 of the load equivalent resistance R4. Therefore, the measured value of the DC current IDC can be used by the microcontroller 70 as a proxy for the value of the equivalent conductance G4 without having to determine the equivalent conductance G4 or the equivalent resistance R4, thereby reducing and simplifying the calculations that need to be performed.

[0272] Figure 6 A flow chart is shown of a simplified method of operating the power supply circuit 66 according to an embodiment of the present disclosure.

[0273] In a first step 101 , the microcontroller 70 is configured to control a switching signal to switch the transistor switch Q1 on and off to control the current and voltage between the power source 72 and the inductor coil L2 .

[0274] In a second step 102 , the microcontroller 70 is configured to measure the current supplied by the DC / DC voltage converter 76 via the output of the current sensor 80 and to measure the heater module input voltage Vin by multiplying the voltage signal received from the voltage sensor circuit 82 by two.

[0275] In a third step 103 , the microcontroller 70 is configured to determine the equivalent resistance R4 by calculating the quotient of the heater module input voltage Vin and the current supplied by the DC / DC voltage converter 76 .

[0276] In a fourth step 104 , the microcontroller 70 is configured to compare the determined equivalent resistance R4 with a dry receptor threshold value stored in a memory of the microcontroller 70 .

[0277] In a fifth step 105 , if the microcontroller 70 determines that the determined equivalent resistance R4 is equal to or less than the dry susceptor threshold, the microcontroller 70 is configured to determine that the susceptor elements 16 , 18 are supplied with liquid aerosol-forming substrate and to return to the first step 101 .

[0278] In a sixth step 106, if the microcontroller 70 determines that the determined equivalent resistance R4 is greater than the dry susceptor threshold, the microcontroller 70 is configured to determine that the susceptor elements 16, 18 are not supplied with liquid aerosol-forming substrate, and is configured to notify the user that the susceptor elements are not supplied with sufficient liquid aerosol-forming substrate. In this embodiment, the notification includes the microcontroller 70 lighting a light emitting diode (not shown).

[0279] Figure 7 A flow chart is shown of a simplified method of operating the power supply circuit 66 according to another embodiment of the present disclosure.

[0280] In a first step 101 , the microcontroller 70 is configured to control a switching signal to switch the transistor switch Q1 on and off to control the current and voltage between the power source 72 and the inductor coil L2 .

[0281] In a second step 102 , the microcontroller 70 is configured to measure the current supplied by the DC / DC voltage converter 76 via the output of the current sensor 80 .

[0282] In a third step 104, the microcontroller is configured to compare the measured current supplied by the DC / DC voltage converter 76 with a dry receptor threshold value stored in the memory of the microcontroller 70. In this embodiment, the current supplied by the DC / DC voltage converter 76 is used as a proxy for the value of the equivalent conductance G4 of the load equivalent resistance R4.

[0283] In a fourth step 105 , if the microcontroller 70 determines that the measured current is greater than or equal to the dry susceptor threshold, the microcontroller 70 is configured to determine that the susceptor elements 16 , 18 are supplied with liquid aerosol-forming substrate and to return to the first step 101 .

[0284] In a fifth step 106, if the microcontroller 70 determines that the measured current is less than the dry susceptor threshold, the microcontroller 70 is configured to determine that the susceptor elements 16, 18 are not supplied with liquid aerosol-forming substrate, and is configured to notify the user that the susceptor elements are not supplied with sufficient liquid aerosol-forming substrate. In this embodiment, the notification includes the microcontroller 70 lighting a light emitting diode (not shown).

[0285] In a sixth step 107 , if the microcontroller 70 determines that the measured current is equal to or greater than the dry receptor threshold, the microcontroller 70 is configured to control the switch signal to turn off the transistor switch to prevent current and voltage between the power supply 72 and the inductor coil L2 .

[0286] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers representing amounts, quantities, percentages, etc. should be understood to be modified by the term "about" in all cases. Moreover, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein that may or may not be specifically listed herein. Therefore, in this context, the number A is understood to be A±{5%}A. Within this context, the number A can be regarded as including a value within the general standard error for the measurement of the attribute modified by the number A. In certain cases used in the appended claims, the number A may deviate from the percentages listed above, provided that the amount of A deviation does not substantially affect the basic features and novel features of the claimed invention. Moreover, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein that may or may not be specifically listed herein.

Claims

1. A power supply circuit for an aerosol generating device, the aerosol generating device being configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the power supply circuit comprising: an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element; power supply; as well as A controller, wherein the controller is configured to: controlling at least one of a current and a voltage between the power source and the inductor coil; comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; as well as Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

2. A power supply circuit according to claim 1, wherein the controller is further configured to notify a user when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

3. A power supply circuit according to any one of claims 1 or 2, wherein the controller is further configured to prevent current from being supplied from the power supply to the inductor coil when it is determined that the susceptor element is not supplied with the liquid aerosol-forming substrate.

4. The power supply circuit of any one of claims 1 to 3, wherein the controller is configured to control at least one of a current and a voltage from the power supply to the inductor coil such that between about 6 Watts and about 12 Watts of power is supplied to the inductor coil, and optionally about 8 Watts to about 10 Watts is supplied to the inductor coil.

5. The power supply circuit of any one of claims 1 to 4, wherein the controller is further configured to determine an equivalent resistance, the equivalent resistance being the quotient of the voltage and the current, and wherein the comparison of at least one of the current and the voltage with the dry receptor threshold is a comparison of the equivalent resistance with the dry receptor threshold.

6. The power circuit of claim 5, wherein the dry susceptor threshold is at least 1.05 ohms, and optionally between about 1.05 ohms and 2.20 ohms.

7. The power circuit of claim 5 or 6, wherein the controller is configured to control at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent resistance, and optionally wherein the target equivalent resistance is between about 0.25 ohms and about 1.7 ohms.

8. The power circuit of claim 7, wherein the dry susceptor threshold is an equivalent resistance at least 15% greater than the target equivalent resistance, optionally at least 20% greater than the target equivalent resistance, and optionally between 15% and 50% greater than the target equivalent resistance.

9. The power supply circuit of any one of claims 1 to 4, wherein the controller is further configured to determine an equivalent conductance, the equivalent conductance being the quotient of the current and the voltage, and wherein the comparison of at least one of the current and the voltage to a dry receptor threshold is a comparison of the equivalent conductance to the dry receptor threshold.

10. The power circuit of claim 9, wherein the dry susceptor threshold is no less than 0.95 Siemens, and optionally between about 0.70 Siemens and about 0.95 Siemens.

11. The power circuit of claim 9 or 10, wherein the controller is configured to control at least one of a current and a voltage from the power supply to the inductor coil corresponding to a target equivalent conductance, and optionally wherein the target equivalent conductance is between about 0.60 Siemens and about 4.00 Siemens.

12. The power circuit of claim 11, wherein the dry susceptor threshold is at least 15% less than the target equivalent conductance, optionally at least 20% less than the target equivalent conductance, and optionally between about 15% and about 50% less than the target equivalent conductance.

13. An aerosol generating device configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating device being connectable to a cartridge comprising the susceptor element, and comprising a power supply circuit comprising: an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element; power supply; as well as A controller, wherein the controller is configured to: controlling at least one of a current and a voltage between the power source and the inductor coil; comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; as well as Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

14. An aerosol generating system comprising: A cartridge, comprising: a receptor element; and a liquid aerosol-forming substrate supplied to the susceptor element; and an aerosol generating device, which is coupleable to the cartridge and is configured to heat the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating device comprising a power circuit comprising: an inductor coil for generating an alternating magnetic field for heating the susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element; Power supply; and A controller, wherein the controller is configured to: controlling at least one of a current and a voltage between the power source and the inductor coil; comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; and Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

15. A method of operating an aerosol generating device, the aerosol generating device comprising a power supply and an inductor coil, and configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the method comprising: controlling at least one of a current and a voltage between the power source and the inductor coil; comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry receptor threshold; as well as Based on the comparison it is determined whether the susceptor element is supplied with the liquid aerosol-forming substrate.

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