Aerosol generating system with detection of delivery of liquid aerosol-forming substrate to a susceptor element

Abstract

A power supply circuit (66) for an aerosol generating device (60), the aerosol generating device (60) configured to heat the susceptor elements (16, 18) to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor elements (16, 18). The power supply circuit (66) includes an inductor coil (68) for generating an alternating magnetic field for heating the susceptor elements (16, 18) to generate an aerosol from the liquid aerosol-forming substrate supplied to the susceptor elements (16, 18), a power supply (72), and a controller (70). The controller (70) is configured to control at least one of a current and a voltage between the power supply (72) and the inductor coil (68), compare at least one of the current and the voltage between the power supply (72) and the inductor coil (68) to a dry susceptor threshold, and determine whether the liquid aerosol-forming substrate is supplied to the susceptor elements (16, 18) based on the comparison. Also provided are an aerosol generation device (60) with a power supply circuit (66), an aerosol generation system including the aerosol generation device (60), and a method of operating an aerosol generation device (60) with a power supply circuit (66).

Description

[Technical Field]

[0001] The present disclosure relates to a power supply circuit for an aerosol generating device, an aerosol generating device including a power supply circuit, an aerosol generating system including an 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 configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element.

[0002] Aerosol generation systems employing induction heating to heat a liquid aerosol-forming substrate to generate an aerosol for inhalation by a user are generally known in the prior art. These systems typically include an aerosol generating device including an induction heating assembly and a cartridge containing a liquid aerosol-forming substrate capable of releasing a volatile compound upon heating, which cools to form an inhalable aerosol. The cartridge is configured to be coupled to the aerosol generating device. The induction heating assembly includes an inductor coil configured to generate an alternating magnetic field. A susceptor element forming part of either the cartridge or the device is disposed 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, it heats by at least one of Joule heating from eddy currents induced within the susceptor element and hysteresis losses. The heated susceptor element heats a liquid aerosol-forming substrate supplied to the susceptor element, releasing a volatile compound from the liquid aerosol-forming substrate, which cools to form an inhalable aerosol.

[0003] Typically, the aerosol generating device is reusable, and the liquid aerosol-forming substrate is contained in a disposable cartridge. During use, the liquid aerosol-forming substrate is vaporized to generate an aerosol, and after a period of use, e.g., a predetermined number of puffs by a user, the liquid aerosol-forming substrate will be depleted. Once the liquid aerosol-forming substrate is depleted, the cartridge should be replaced before the next use of the aerosol generating device.

[0004] It would be desirable to provide an aerosol generating device that has the ability to detect when insufficient liquid aerosol-forming substrate is supplied to the susceptor element to generate an aerosol.It would be desirable to provide an aerosol generating device that has the ability to detect when the liquid aerosol-forming substrate in the cartridge is depleted. Summary of the Invention

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

[0006] The inventors have realized 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 being heated and vaporized. As a result, a sufficiently large deviation in at least one of the current and voltage supplied from the power supply to the inductor coil from the constant value achieved while the liquid aerosol-forming substrate is being heated and vaporized may indicate that the susceptor element is not being supplied with a liquid aerosol-forming substrate.

[0007] Determining whether a susceptor element is being supplied with a liquid aerosol-forming substrate can be useful for several reasons. For example, determining that a susceptor element is not being supplied with a liquid aerosol-forming substrate may indicate that a reservoir of liquid aerosol-forming substrate has been depleted and requires refilling or replacement. For example, determining that a susceptor element is not being supplied with a liquid aerosol-forming substrate may indicate that the device is not functioning properly. For example, determining that a susceptor element is not being supplied with a liquid aerosol-forming substrate may indicate that an aerosol-generating device is not generating the expected quantity or quality of aerosol because insufficient liquid aerosol-forming substrate is being 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 being supplied with a 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 susceptor element is not being supplied with 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 notify the user by illuminating a light-emitting diode. The controller may be configured to display a 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 loudspeaker to notify the user.

[0010] In some preferred embodiments, the controller is configured to control at least one of the current and voltage from the power source to the inductor coil, thereby supplying power to the inductor coil to heat a susceptor element coupled to the inductor coil and generate 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, thereby providing between about 6 watts and about 12 watts of power 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, thereby providing between about 8 watts and about 10 watts of power to the inductor coil.

[0012] In some of these preferred embodiments, 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 a liquid aerosol-forming substrate.

[0013] The controller may be configured to control at least one of the current and the 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 source. Preferably, the power source is a DC power source and the voltage is a DC supply voltage from the DC power source. In some preferred embodiments, the powering electronics may comprise a DC / DC converter. The DC / DC converter may receive the DC supply voltage from the DC power source. 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, the powering electronics may comprise a DC / AC converter, and the current may comprise a DC current received by the DC / AC converter, as described in more detail below.

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

[0020] In some embodiments, the dry susceptor threshold is recorded in the memory of the controller at the factory before the aerosol generating device is used.

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

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

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

[0024] The comparison of at least one of the current and voltage between the power source and the inductor coil to a dry susceptor threshold may be a comparison of the voltage between the power source and the inductor coil to a dry susceptor threshold. The comparison of at least one of the current and voltage between the power source and the inductor coil to a dry susceptor threshold may be a comparison of the current between the power source and the inductor coil to a dry susceptor threshold. The comparison of at least one of the current and voltage between the power source and the inductor coil to a dry susceptor threshold may be a comparison of both the current and the voltage between the power source and the inductor coil to a dry susceptor threshold.

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

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

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

[0028] If 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 percent less than the initial current measurement. The dry susceptor threshold may be 15 percent to 50 percent less than the initial current measurement.

[0029] In some preferred embodiments, the controller is further configured to determine an equivalent or 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 from the quotient of the voltage and the current between the power source and the inductor coil. The equivalent resistance includes the resistance of the inductor coil and the apparent resistance of the susceptor element. The apparent resistance of the susceptor element is the additional resistance "see" 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 from 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 against 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 against 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 the current and voltage between the power source and the inductor coil corresponding to a target equivalent or apparent resistance of the susceptor element. In these embodiments, the controller may be configured to determine the equivalent or apparent resistance of the susceptor element and control at least one of the current and voltage between the power source and the inductor coil to achieve the target equivalent or apparent resistance of the susceptor element. The target equivalent or 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 percent greater than the target equivalent or apparent resistance of the susceptor element. The dry susceptor threshold may be at least 20 percent greater than the target equivalent or apparent resistance of the susceptor element. The dry susceptor threshold may be 15 to 50 percent greater than the target equivalent or apparent resistance of the susceptor element.

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

[0035] If 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 from the measurement of at least one of the initial current and the initial voltage. If the controller is configured to compare the determined equivalent resistance or apparent resistance of the susceptor element to the dry susceptor threshold, the dry susceptor threshold may be at least 20 percent greater than the determined initial equivalent resistance or the determined initial apparent resistance of the susceptor element. The dry susceptor threshold may be 15 percent to 50 percent 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 from 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 "seeing" 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 from 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 susceptor threshold. In some of these preferred embodiments, the controller may be configured to compare the determined apparent conductance of the susceptor element to a dry susceptor threshold. In these preferred embodiments, the dry susceptor threshold may be 0.95 siemens or greater. The dry susceptor 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 the current and voltage between the power source and the inductor coil corresponding to a target equivalent conductance or target apparent conductance of the susceptor element. In these embodiments, the controller may be configured to determine the equivalent conductance or apparent conductance of the susceptor element and control at least one of the current and voltage between the power source and the inductor coil to achieve the target equivalent conductance or target apparent conductance of the susceptor element. The target equivalent conductance or 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 percent less than the target equivalent or apparent conductance of the susceptor element. The dry susceptor threshold may be at least 20 percent less than the target equivalent or apparent conductance of the susceptor element. The dry susceptor threshold may be 15 to 50 percent less than the target equivalent or apparent conductance of the susceptor element.

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

[0041] If the dry susceptor threshold is based on measurements of at least one of an initial current and an initial voltage between the power source and the inductor coil, the controller may be configured to determine an initial equivalent conductance or an initial apparent conductance of the susceptor element from the measurements of at least one of the initial current and the initial voltage. If the controller is configured to compare the determined equivalent conductance or the determined initial apparent conductance of the susceptor element to the dry susceptor threshold, the dry susceptor threshold may be at least 20 percent less than the determined initial equivalent conductance or the determined initial apparent conductance of the susceptor element. The dry susceptor threshold may be 15 percent to 50 percent less than the determined initial equivalent conductance or the determined initial apparent conductance of the susceptor element.

[0042] The power supply 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 or 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 supply circuit may include any suitable number of inductor coils. The power supply circuit may include a single inductor coil. The power supply circuit may include multiple inductor coils. The power supply 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 numerous charge and discharge cycles. The power source may have a capacity that allows for storage of energy sufficient for one or more user experiences with the aerosol generation system; for example, the power source may have a capacity sufficient to allow continuous generation of aerosol for a period of approximately six minutes, corresponding to the typical time it takes to smoke a conventional cigarette, or for a multiple of six minutes. In another embodiment, the power source may have a capacity sufficient to allow for a predetermined number of puffs or for discontinuous activation of the atomizer assembly.

[0047] The controller may be any suitable controller. The controller may include a memory. The drying susceptor 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 circuit chip (ASIC) or other electronic circuit capable of providing control. The controller may be configured to provide power to the inductor coil continuously after activation of the device, or may be configured to provide power intermittently, such as with each puff. Power may be provided to the inductor coil in the form of current pulses, for example, by 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 a 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). If the inductor coil is a helical coil or a tubular coil, the alternating current may have a frequency between 500 kilohertz (kHz) and 30 megahertz (MHz). If the inductor coil is a planar 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 the heating portion of the susceptor element located within the alternating magnetic field. A suitable frequency for the alternating magnetic field may be 100 kilohertz (kHz) to 30 megahertz (MHz).

[0050] The power supply circuit may include additional electronic components, for example, in some embodiments the controller may include a sensor element, a switch element, or a display element.

[0051] If the power source is a DC power source, the power supply circuit may further include a DC / AC converter. The DC / AC converter may be disposed between the DC power source 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, and the DC / AC converter further includes an LC (inductor-capacitor) load network, and 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 comprise a DC / DC converter. The DC / DC converter may be disposed between the DC power source and the DC / AC converter. The DC / DC converter may allow DC power sources having different supply voltages to be used with the aerosol generating device without modifying the functionality of the aerosol generating device.

[0055] The power supply circuit may further include a puff detector. The puff detector may be configured to detect when a user puffs on the aerosol generating device. 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] If the power supply circuit includes a puff detector, the controller may be configured to, when the puff detector detects a user puffing on the aerosol-generating device, supply a current and a voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate an aerosol. The controller may be further configured to, when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate, prevent the supply of a current and a voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate an aerosol.

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

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

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

[0060] Also provided is an aerosol generation system comprising an aerosol generation 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 generation device comprises a susceptor element. In some preferred embodiments, the cartridge comprises a susceptor element.

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

[0062] It is also contemplated that an aerosol generation 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 to heat the susceptor element and generate an aerosol from the liquid aerosol-forming substrate supplied to the susceptor element. The power supply circuit may further comprise a power source and a controller. The controller may be configured to control at least one of a current and a voltage between the power source and the inductor coil. The controller may be further configured to compare at least one of the current and the voltage between the power source and the inductor coil to a dry susceptor threshold. The controller may be further configured to determine whether the liquid aerosol-forming substrate is being supplied to the susceptor element 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 typically heatable by at least one of Joule heating through the induction of eddy currents within the susceptor element and hysteresis losses.

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

[0065] The susceptor element may comprise 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 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 comprises a ferritic stainless steel. Suitable ferritic stainless steels include SAE 400 series stainless steels, such as SAE types 409, 410, 420, and 430 stainless steel.

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

[0067] In some preferred embodiments, the susceptor elements are planar. Planar susceptor elements may extend substantially in a plane. In some preferred embodiments, the susceptor element comprises a mesh. The susceptor element may comprise an array of filaments forming the mesh. As used herein, the term "mesh" encompasses grids and arrays of filaments having spaces therebetween. The term mesh also includes woven and nonwoven fabrics.

[0068] The filaments may define gaps between them, and the gaps may have a width of 10 micrometers to 100 micrometers. Preferably, the filaments create capillary action within the gaps such that, in use, source liquid is drawn into the gaps, increasing the contact area between the susceptor element and the liquid.

[0069] The filaments may form a mesh with a size of 160 to 600 mesh US (+ / - 10%) (i.e., 160 to 600 filaments per inch (+ / - 10%)). The gap width may be 35 micrometers to 140 micrometers, or 25 micrometers to 75 micrometers. For example, the gap width may be 40 micrometers or 63 micrometers. The percentage of open area of ​​the mesh, which is the ratio of the gap area to the total area of ​​the mesh, is preferably 25 to 56%. The mesh may be formed using different types of weave or lattice structures. Alternatively, the filaments consist of an array of filaments arranged parallel to one another.

[0070] The filaments may be formed by etching a sheet material such as a foil. This may be particularly advantageous when the heater assembly comprises an array of parallel filaments. Where the heating element comprises a mesh or weave of filaments, the filaments may be formed individually or woven together.

[0071] Preferably, the mesh is sintered. The filaments of the mesh may be sintered together. Advantageously, sintering the mesh creates electrical bonds between filaments extending in different directions. In particular, where the mesh comprises one or more of a woven and a nonwoven fabric, it is advantageous for the mesh to be sintered to create electrical bonds between overlapping filaments.

[0072] A mesh may also be characterized by its ability to retain liquid, as is well understood in the art.

[0073] The filaments of the mesh may have a diameter of 8 micrometers to 100 micrometers, 30 micrometers to 100 micrometers, 8 micrometers to 50 micrometers, or 8 micrometers to 39 micrometers. The filaments of the mesh may have a diameter of 50 micrometers.

[0074] The filaments of the mesh may have any suitable cross-section, for example, the filaments may have a round cross-section or a flattened cross-section.

[0075] Advantageously, the mesh susceptor elements may have a relative permeability of 1 to 40,000. Lower permeability materials may be used when reliance on eddy currents for the majority of heating is desired, and higher permeability materials may be used when hysteresis effects are desired. Preferably, the material has a relative permeability of 500 to 40,000. This may provide efficient heating of the susceptor elements.

[0076] The aerosol generation system comprises a cartridge, which may be connectable to an aerosol generation device.

[0077] The cartridge comprises a liquid reservoir. Preferably, the cartridge further comprises a susceptor element. In some preferred embodiments in which the cartridge comprises the susceptor element and the aerosol generation device comprises a cavity configured to receive a portion of the cartridge and couple the cartridge to the aerosol generation device, the susceptor element is disposed within the cartridge in a position to be received within the cavity of the aerosol generation device when the cartridge is coupled to the aerosol generation device.

[0078] If the aerosol generation system includes a cartridge containing a susceptor element, the inductor coil may be disposed within the device so that, when the cartridge is coupled to the aerosol generation device, the alternating magnetic field penetrates the cartridge, and in particular the susceptor element within the cartridge. If the aerosol generation device includes a cavity for receiving the cartridge, the inductor coil may be disposed so that the alternating magnetic field penetrates the cavity. The inductor coil may be disposed at, within, or around the cavity. In some embodiments, the inductor coil may surround the cavity. The inductor coil may be a tubular, spiral, or helical coil that substantially surrounds the cavity. In other embodiments, the coil may be disposed on a side of the cavity.

[0079] In some embodiments in which the susceptor element is planar and extends parallel to the plane, the inductor coil may be arranged to generate an alternating magnetic field that penetrates the susceptor assembly in a direction substantially parallel to the plane.

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

[0081] The tubular or spiral inductor coil may surround the susceptor element. The planar or flat inductor coil may be disposed on one side of the susceptor element. The planar or flat inductor coil may be circular, elliptical, or rectangular. Preferably, the shape of the planar or flat inductor coil substantially corresponds to the shape of the susceptor element.

[0082] When the susceptor element is substantially planar and extends parallel to a first plane, the inductor coil can be a flat inductor coil extending in a second plane substantially parallel to the first plane, in which arrangement the inductor coil is arranged to generate an alternating magnetic field that penetrates the susceptor assembly in a direction substantially perpendicular to the first plane.

[0083] In some preferred embodiments, the susceptor assembly includes a planar susceptor element, and the power supply circuit includes a first planar inductor coil and a second planar 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 and second planes. The susceptor element is disposed between the first and second inductor coils. 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 facing opposite the first side in a direction substantially perpendicular to the first plane. Advantageously, such an arrangement may 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 and opposite direction.

[0084] 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 sense to the second inductor coil, such 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 sense, and the controller may be configured to supply alternating current to each of the first inductor coil and the second inductor coil, such 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 senses.

[0085] The cartridge includes a liquid reservoir configured to hold a liquid aerosol-forming substrate. Specifically, the liquid reservoir is configured to hold the liquid aerosol-forming substrate to be supplied to the susceptor element. The liquid reservoir may have any suitable shape and size depending on the requirements of the aerosol generation system.

[0086] In some embodiments, the liquid reservoir contains a retention material for retaining the liquid aerosol-forming substrate. If the liquid reservoir comprises multiple sections, the retention material may be located in one or more of the sections, or may be located in all of the sections. The retention material may be a foam material, a spongy material, or a collection of fibers. The retention material may be formed from a polymer or copolymer. In one embodiment, the retention material is a spun polymer.

[0087] When the cartridge includes a suction element and a retention material, the suction element and the retention material may be formed from 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 suction element of the susceptor assembly. The retention material may contact the suction element of the susceptor assembly. In some embodiments, the cartridge comprises a susceptor assembly. The susceptor assembly comprises a susceptor element. The susceptor assembly may further comprise a liquid transfer element. The liquid transfer element may be in fluid communication with the susceptor element. The liquid transfer element may be in fluid communication with a liquid reservoir. The liquid transfer element may be arranged to transport the liquid aerosol-forming substrate from the liquid reservoir to the susceptor element. Specifically, the liquid transfer element may be arranged to transport the 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 transfer element. The susceptor element may be integral with the liquid transfer element. Providing a liquid transfer element may improve wetting of the susceptor element, thereby increasing aerosol generation by the system.

[0088] In some preferred embodiments, the liquid transfer element is a wicking element, which may allow the susceptor element to be made from a material that does not itself provide good wicking or wetting capabilities.

[0089] The susceptor assembly may include a plurality of susceptor elements. When the susceptor assembly includes a plurality of susceptor elements and a plurality of liquid transfer elements, each susceptor element may be disposed in fluid communication with a liquid transfer element. The susceptor assembly may include a plurality of susceptor elements and a plurality of suction elements.

[0090] 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 suction element may be disposed in a 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 suction element are substantially planar, the first susceptor element being disposed on a first side of the planar suction element, and the second susceptor element being disposed on a second side of the planar suction element opposite the first side.

[0091] The susceptor assembly may include a heating region and at least one mounting region. The heating region is a region of the susceptor assembly configured to be heated to a temperature required to vaporize the aerosol-forming substrate when penetrated by an appropriate alternating magnetic field. The at least one mounting region of the susceptor assembly is a region configured to contact a cartridge housing or susceptor element holder. In some preferred embodiments, the at least one mounting region extends into the liquid reservoir.

[0092] When the liquid transfer assembly includes a wicking element, the wicking element may include a capillary material. A capillary material is a material capable of transferring liquid from one end of the material to another by capillary action. The capillary material may have a fibrous or spongy structure. The capillary material preferably includes a bundle of capillaries. For example, the capillary material may include multiple fibers or threads or other fine tubes. The fibers or threads may be generally aligned to transport the liquid aerosol-forming substrate toward the susceptor element. In some embodiments, the capillary material may include a spongy or foam-like material. The structure of the capillary material may form multiple small holes or tubes through which the liquid aerosol-forming substrate can transfer by capillary action. When the susceptor element includes gaps or openings, the capillary material may extend into the gaps or openings in the susceptor element. The susceptor element may draw the liquid aerosol-forming substrate into the gaps or openings by capillary action.

[0093] The suction element may comprise an electrically insulating material. The suction element may comprise a thermally insulating material. The suction element may comprise a hydrophilic material. The suction element may comprise an oleophilic material. Advantageously, forming the suction element from a hydrophilic or oleophilic material may facilitate transport of the aerosol-forming substrate through the suction element.

[0094] The suction element may comprise a non-metallic material. Examples of suitable materials for the suction element include sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foam metal or plastic materials, and fibrous materials, such as fibrous materials made of spun or extruded fibers (such as cellulose acetate, polyester, or bonded polyolefin, polyethylene, terylene, or polypropylene fibers, nylon fibers, or ceramic or glass fibers). Suitable materials for the suction element may include cellulosic materials such as cotton or rayon. Preferably, the suction element may comprise rayon. The suction element may consist of rayon. A suction element comprising a porous ceramic material may be particularly advantageous when one or both of the susceptor elements comprises a conductive material deposited thereon. A suction element comprising a porous ceramic material may be an advantageous substrate for a manufacturing process associated with the deposition of a conductive material.

[0095] The cartridge may comprise an aerosol-forming substrate. As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing a volatile compound capable of forming an aerosol. The volatile compound may be released by heating the aerosol-forming substrate. The cartridge preferably contains a liquid aerosol-forming substrate.

[0096] The aerosol-forming substrate may be liquid at room temperature. The aerosol-forming substrate may contain both liquid and solid components. The liquid aerosol-forming substrate may contain nicotine. The nicotine-containing liquid aerosol-forming substrate may be a nicotine salt matrix. The liquid aerosol-forming substrate may contain plant-derived material. The liquid aerosol-forming substrate may contain tobacco. The liquid aerosol-forming substrate may contain tobacco-containing material containing volatile tobacco flavour compounds that are released from the aerosol-forming substrate upon heating. The liquid aerosol-forming substrate may contain homogenised tobacco material. The liquid aerosol-forming substrate may contain non-tobacco-containing material. The liquid aerosol-forming substrate may contain homogenised plant-derived material.

[0097] The liquid aerosol-forming substrate may include one or more aerosol formers. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense, stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperatures of the system. Examples of suitable aerosol formers include glycerin and propylene glycol. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (e.g., triethylene glycol, 1,3-butanediol, glycerin), esters of polyhydric alcohols (e.g., glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (e.g., dimethyl dodecanedioate, dimethyl tetradecanedioate). The liquid aerosol-forming substrate may include water, solvents, ethanol, plant extracts, and natural or artificial flavors.

[0098] The liquid aerosol-forming substrate may comprise nicotine and at least one aerosol former. The aerosol former may be glycerin or propylene glycol. The aerosol former may comprise both glycerin and propylene glycol. The liquid aerosol-forming substrate may have a nicotine concentration of about 0.5% to about 10%, for example, about 2%.

[0099] The cartridge may include an outer housing. The outer housing may be formed from a durable material. The outer housing may be formed from a liquid-impermeable material. The outer housing may be formed from a moldable plastic material such as polypropylene (PP) or polyethylene terephthalate (PET).

[0100] The susceptor assembly may be disposed within the outer housing. If the cartridge includes a susceptor element holder, the susceptor element holder may be disposed within the outer housing. In some embodiments, the susceptor element holder may be integrally formed with the outer housing. The susceptor element holder may be formed from the same material as the cartridge outer housing, or may be formed from a different material.

[0101] 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 disposed within the outer housing.

[0102] The cartridge may have a mouth end through which the generated aerosol may be inhaled by a user. The cartridge may have a connecting end configured to connect the cartridge to an aerosol generating device.

[0103] The cartridge may define an air inlet. The air inlet may be disposed at or around the connecting end of the cartridge. The cartridge may define a mouth-end opening. A user may be able to inhale aerosol generated from the cartridge through the mouth-end opening. The cartridge may define an enclosed airflow passage from the air inlet to the air outlet. The enclosed airflow passage may extend from the air inlet, past the susceptor element, to the mouth-end opening.

[0104] The enclosed airflow passage may pass through the liquid reservoir. For example, the liquid reservoir may have an annular cross-section defining an interior passage, and the airflow passage may extend through the interior passage of the liquid reservoir.

[0105] The aerosol generating device may include a housing. The housing may be elongated. The housing may comprise any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composites containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. Preferably, the material is lightweight and not brittle.

[0106] The aerosol generator housing may define a cavity for receiving a portion of the cartridge. The aerosol generator may include one or more air inlets. The one or more air inlets may allow ambient air to be drawn into the cavity.

[0107] The aerosol generating device may have a connecting end configured to connect the aerosol generating device to the cartridge. The connecting end may include a cavity for receiving the cartridge.

[0108] The aerosol generating device may have a distal end opposite the connecting end, which may include an electrical connector configured to connect the aerosol generating device to an electrical connector of an external power source for charging the power source of the aerosol generating device.

[0109] The aerosol generating system may be a handheld aerosol generating system configured to allow a user to draw on the mouthpiece and inhale the aerosol through the mouth-end opening. The aerosol generating system may have a size comparable to a conventional cigar or cigarette. The aerosol generating system may have an overall length of about 30 mm to about 150 mm. The aerosol generating system may have an outer diameter of about 5 mm to about 30 mm.

[0110] The aerosol generation system may be configured to deliver nicotine or cannabinoids to a user.

[0111] Also provided is a method of operating an aerosol-generating device, the aerosol-generating device including 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 may include controlling at least one of a current and a voltage between the power supply and the inductor coil. The method may further include comparing at least one of the current and the voltage between the power supply and the inductor coil to a dry susceptor threshold. The method may further include determining whether the liquid aerosol-forming substrate is supplied to the susceptor element based on the comparison.

[0112] In some embodiments, the method further comprises notifying a user when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0113] In some embodiments, the method further comprises preventing current from being supplied from the power source to the inductor coil when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0114] The method may further comprise 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 delivered to the inductor coil. In some embodiments, the current and voltage from the power source to the inductor coil is controlled such that between about 8 Watts and about 10 Watts of power is delivered to the inductor coil.

[0115] In some preferred embodiments, the method further includes determining an equivalent 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.

[0116] In some of these preferred embodiments, comparing at least one of the current and the voltage to a dry susceptor threshold is a comparison of an equivalent resistance to a dry susceptor threshold, which may be at least 1.05 ohms, and optionally between about 1.05 ohms and 2.20 ohms.

[0117] In some embodiments, the method further includes controlling at least one of a current and a voltage from the power source 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 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 percent greater than the target equivalent resistance or target apparent resistance of the susceptor element. Optionally, the dry susceptor threshold may be at least 20 percent greater than the target equivalent resistance or target apparent resistance of the susceptor element, or between 15 percent and 50 percent greater than the target equivalent resistance or target apparent resistance of the susceptor element.

[0118] In some embodiments, the method further includes determining an equivalent or apparent conductance of the susceptor element. As described above, the equivalent conductance includes the quotient of the current and voltage between the power source and 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 from the quotient of the current and voltage between the power source and the inductor coil.

[0119] In some of these embodiments, comparing at least one of the current and voltage to a dry susceptor threshold comprises comparing an equivalent conductance or apparent conductance of the susceptor element to the dry susceptor threshold, which may be 0.95 siemens or greater, and optionally between about 0.70 siemens and about 0.95 siemens.

[0120] In some embodiments, the method further includes controlling at least one of a current and a voltage from the power source 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 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 percent less than the target equivalent conductance or target apparent conductance of the susceptor element. Optionally, the dry susceptor threshold may be at least 20 percent less than the target equivalent conductance or target apparent conductance of the susceptor element, or between about 15 percent and about 50 percent less than the target equivalent conductance or target apparent conductance of the susceptor element.

[0121] In some preferred embodiments, the method further includes measuring a voltage between the power source and the inductor coil.

[0122] In some preferred embodiments, the method further includes measuring a current between the power source and the inductor coil.

[0123] In some embodiments, the aerosol-generating device further comprises a puff detector, and the method further comprises detecting when a user puffs on the aerosol-generating device using the puff detector. In some of these embodiments, the method further comprises, when the puff detector detects that a user puffs on the aerosol-generating device, supplying a current and a voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate the aerosol.

[0124] In some embodiments, the method further includes, when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate, generating an alternating magnetic field to heat the susceptor element and prevent the supply of current and voltage to the inductor coil to generate the aerosol.

[0125] It will be appreciated that any feature described herein with respect to one embodiment may also be applicable to other embodiments, and features described with respect to a power supply circuit may be equally applicable to an aerosol generating device comprising the power supply circuit or to an aerosol generating system comprising the power supply circuit.

[0126] The present invention is defined in the claims. However, below is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features described above, for example, with any one or more features of other examples, embodiments, or aspects described herein.

[0127] [Example 1] 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 and A controller; a controller 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 susceptor threshold; and determining whether the susceptor element is provided with a liquid aerosol-forming substrate based on the comparison; A power supply circuit configured as follows.

[0128] [Example 2] 2. The power supply 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 being supplied with a liquid aerosol-forming substrate.

[0129] [Example 3] 3. The power supply circuit according to any one of Examples 1-2, wherein the controller is further configured to prevent current from being supplied from the power source to the inductor coil when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0130] [Example 4] A power supply circuit according to any one of Examples 1 to 3, wherein the controller is configured to control at least one of the current and voltage from the power source to the inductor coil, thereby supplying between about 6 watts and about 12 watts of power to the inductor coil, and optionally supplying between about 8 watts and about 10 watts to the inductor coil.

[0131] [Example 5] 5. The 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 a quotient of the voltage and the current, and the comparison of at least one of the current and the voltage to a dry susceptor threshold is a comparison of the equivalent resistance to a dry susceptor threshold.

[0132] [Example 6] The power supply circuit according to example 5, wherein the dry susceptor threshold is at least 1.05 ohms, and optionally between about 1.05 ohms and 2.20 ohms.

[0133] [Example 7] The power supply circuit according to example 5 or example 6, wherein the controller is configured to control at least one of a current and a voltage from the power source to the inductor coil corresponding to a target equivalent resistance, and optionally, the target equivalent resistance is between about 0.25 ohms and about 1.7 ohms.

[0134] [Example 8] The power supply circuit according to example 7, wherein the dry susceptor threshold is an equivalent resistance at least 15 percent greater than the target equivalent resistance, optionally at least 20 percent greater than the target equivalent resistance, and optionally 15 percent to 50 percent greater than the target equivalent resistance.

[0135] [Example 9] 5. The power supply 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 a quotient of the current and the voltage, and wherein the comparison of at least one of the current and the voltage to a dry susceptor threshold is a comparison of the equivalent conductance to a dry susceptor threshold.

[0136] [Example 10] The power supply circuit according to example 9, wherein the dry susceptor threshold is greater than or equal to 0.95 Siemens, optionally between about 0.70 Siemens and about 0.95 Siemens.

[0137] [Example 11] The power supply 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 source to the inductor coil corresponding to a target equivalent conductance, optionally wherein the target equivalent conductance is between about 0.60 siemens and about 4.00 siemens.

[0138] [Example 12] The power supply circuit according to example 11, wherein the dry susceptor threshold is at least 15 percent less than the target equivalent conductance, optionally at least 20 percent less than the target equivalent conductance, and optionally between about 15 percent and about 50 percent less than the target equivalent conductance.

[0139] [Example 13] 13. The power supply circuit according to any one of Examples 1 to 12, wherein the controller is further configured to measure a voltage between the power source and the inductor coil.

[0140] [Example 14] 14. The power supply circuit according to any one of Examples 1 to 13, wherein the controller is further configured to measure a current between the power source and the inductor coil.

[0141] [Example 15] The power supply circuit according to any one of Examples 1 to 14, wherein the power supply is a DC power supply.

[0142] [Example 16] 16. The power supply circuit according to Example 15, further comprising a DC / AC converter disposed between the DC power source and the inductor coil.

[0143] [Example 17] 17. The power supply circuit according to Example 16, wherein the DC / AC converter includes a capacitor.

[0144] [Example 18] 18. The power supply circuit according to example 16 or example 17, wherein the DC / AC converter comprises an LC (inductor-capacitor) load network.

[0145] [Example 19] 17. A power supply circuit according to Example 16, wherein the DC / AC converter comprises a capacitor, and the DC / AC converter further comprises an LC (inductor-capacitor) load network, the LC load network comprising an inductor coil and a capacitor, and optionally the inductor coil is connected in series with the capacitor.

[0146] [Example 20] 20. The power supply circuit according to any one of Examples 16 to 19, wherein the DC / AC converter comprises a class E power amplifier.

[0147] [Example 21] 20. The power supply circuit according to any one of Examples 16 to 19, wherein the DC / AC converter comprises a class D power amplifier.

[0148] [Example 22] 22. The power supply 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.

[0149] [Example 23] 23. The power supply circuit according to example 22, wherein the controller is further configured to supply current and voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element, and to generate an aerosol when the smoke detector detects a user inhaling the aerosol generating device.

[0150] [Example 24] 24. The power supply circuit according to Example 23, wherein the controller is further configured to generate an alternating magnetic field to heat the susceptor element and prevent the supply of current and voltage to the inductor coil for generating an aerosol when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0151] [Example 25] An aerosol generating apparatus configured to heat a susceptor element to generate an aerosol from a liquid aerosol-forming substrate supplied to the susceptor element, the aerosol generating apparatus comprising a power supply circuit according to any one of Examples 1 to 24.

[0152] [Example 26] 1. 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 the aerosol generating device 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; a controller 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 susceptor threshold; and determining whether the susceptor element is provided with a liquid aerosol-forming substrate based on the comparison; a controller configured to An aerosol generating device comprising a power supply circuit comprising:

[0153] [Example 27] An aerosol generation device according to example 25 or example 26, further comprising a cavity configured to receive a portion of the cartridge and to couple the cartridge to the aerosol generation device.

[0154] [Example 28] 28. An aerosol generating device according to example 27, wherein the inductor coil is disposed in or around the cavity.

[0155] [Example 29] An aerosol generating device according to example 27 or example 28, wherein the inductor coil is arranged to generate an alternating magnetic field within the cavity.

[0156] [Example 30] 30. An aerosol generating device according to any one of Examples 27 to 29, wherein the inductor coil at least partially surrounds the cavity.

[0157] [Example 31] a cartridge including a susceptor element and a liquid aerosol-forming substrate supplied to the susceptor element; An aerosol generating system comprising the aerosol generating device according to any one of Examples 25 to 30.

[0158] [Example 32] 1. An aerosol generating system comprising: A cartridge, a susceptor element; a liquid aerosol-forming substrate supplied to a susceptor element; a cartridge comprising: 1. An aerosol generating device connectable to a cartridge and 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: 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 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 susceptor threshold; and determining whether the susceptor element is provided with a liquid aerosol-forming substrate based on the comparison; a controller configured to an aerosol generating device comprising a power supply circuit comprising: An aerosol generating system comprising:

[0159] [Example 33] The aerosol-generating system according to example 31 or example 32, wherein the cartridge further comprises a liquid transfer element arranged to deliver a liquid aerosol-forming substrate to the susceptor element.

[0160] [Example 34] The aerosol-generating system according to any one of Examples 31 to 33, wherein the susceptor element is a mesh susceptor element.

[0161] [Example 35] An aerosol generation system according to any one of Examples 31 to 34, wherein the aerosol generation device has a cavity configured to receive a portion of the cartridge and connect the cartridge to the aerosol generation device, and the susceptor element is disposed within the cartridge in a position to be received within the cavity of the aerosol generation device when the cartridge is connected to the aerosol generation device.

[0162] [Example 36] 1. 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 a power source and an inductor coil; comparing at least one of a current and a voltage between the power supply and the inductor coil to a dry susceptor threshold; and determining whether the susceptor element is supplied with a liquid aerosol-forming substrate based on the comparison.

[0163] [Example 37] 37. The method according to example 36, further comprising notifying a user when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0164] [Example 38] The method according to any one of Examples 36 or 37, further comprising preventing current from being supplied from the power source to the inductor coil when it is determined that the susceptor element is not supplied with a liquid aerosol-forming substrate.

[0165] [Example 39] A method according to any one of Examples 36 to 38, further comprising the controller controlling at least one of the current and voltage from the power source to the inductor coil, thereby supplying between about 6 watts and about 12 watts of power to the inductor coil, and optionally supplying between about 8 watts and about 10 watts to the inductor coil.

[0166] [Example 40] The method according to any one of Examples 36-39, further comprising determining an equivalent resistance, wherein the equivalent resistance is the quotient of the voltage and the current, and wherein comparing at least one of the current and the voltage to a dry susceptor threshold is comparing the equivalent resistance to a dry susceptor threshold.

[0167] [Example 41] The method according to example 41, wherein the dry susceptor threshold is at least 1.05 ohms, optionally between about 1.05 ohms and 2.20 ohms.

[0168] [Example 42] The method according to Example 41 or Example 42, further comprising controlling at least one of the current and voltage from the power source to the inductor coil corresponding to a target equivalent resistance, optionally wherein the target equivalent resistance is between about 0.25 ohms and about 1.7 ohms.

[0169] [Example 43] The method according to example 42, wherein the dry susceptor threshold is an equivalent resistance at least 15 percent greater than the target equivalent resistance, optionally at least 20 percent greater than the target equivalent resistance, and optionally between 15 percent and 50 percent greater than the target equivalent resistance.

[0170] [Example 44] 40. The method according to any one of Examples 36-39, further comprising determining an equivalent conductance, wherein the equivalent conductance is 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 susceptor threshold is a comparison of the equivalent conductance to a dry susceptor threshold.

[0171] [Example 45] The method according to example 44, wherein the dry susceptor threshold is greater than or equal to 0.95 Siemens, and optionally between about 0.70 Siemens and about 0.95 Siemens.

[0172] [Example 46] A method according to Example 44 or Example 45, further comprising the controller controlling at least one of the current and voltage from the power source to the inductor coil corresponding to a target equivalent conductance, and optionally, the target equivalent conductance being between about 0.60 siemens and about 4.00 siemens.

[0173] [Example 47] The method according to example 46, wherein the dry susceptor threshold is at least 15 percent less than the target equivalent conductance, optionally at least 20 percent less than the target equivalent conductance, and optionally between about 15 percent and about 50 percent less than the target equivalent conductance.

[0174] [Example 48] 48. The method according to any one of Examples 36-47, further comprising measuring a voltage between the power source and the inductor coil.

[0175] [Example 49] The method according to any one of Examples 36-48, further comprising measuring a current between the power source and the inductor coil.

[0176] [Example 50] The 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 detecting when a user puffs on the aerosol generating device using the puff detector.

[0177] [Example 51] The method according to Example 50, further comprising, when the smoke detector detects when a user inhales on the aerosol generating device, supplying current and voltage to the inductor coil to generate an alternating magnetic field to heat the susceptor element and generate an aerosol.

[0178] [Example 52] A method according to Example 51, further comprising preventing the supply of current and voltage to the inductor coil to 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.

[0179] The embodiments will now be further described with reference to the figures. [Brief explanation of the drawings]

[0180] [Figure 1a] FIG. 1a shows a schematic diagram of an aerosol generation system according to an embodiment of the present disclosure, the aerosol generation system comprising an aerosol generator and a cartridge. [Figure 1b] FIG. 1b shows a schematic diagram of the aerosol generation system of FIG. 1a rotated by 90 degrees about the central longitudinal axis of the aerosol generation system. [Figure 2a] FIG. 2a shows a schematic diagram of a cartridge for an aerosol generation system according to an embodiment of the present disclosure, the cartridge being in a storage configuration. [Figure 2b] FIG. 2b shows a schematic view of the cartridge of FIG. 2a rotated by 90 degrees about the central longitudinal axis of the cartridge. [Figure 2c] Figure 2c shows a schematic view of the cartridge of Figure 2a, with the cartridge in a use configuration. [Figure 3a] FIG. 3a shows a side view of the susceptor assembly of the cartridge of FIGS. 2a, 2b, and 2c. [Figure 3b] FIG. 3b shows a perspective view of the susceptor assembly of FIG. 3a. [Figure 3c] FIG. 3c shows a top view of the susceptor assembly of FIG. 3a. [Figure 4] FIG. 4 shows a schematic block diagram of the power supply circuit of the aerosol generating device of FIGS. 1a and 1b. [Figure 5] FIG. 5 shows a schematic circuit diagram of the heater module of the power supply circuit of FIG. [Figure 6]FIG. 6 shows a flow diagram of a simplified method of operating the power supply circuit of FIG. 4 according to an embodiment of the present disclosure. [Figure 7] FIG. 7 shows a flow diagram of a simplified method of operating the power supply circuit of FIG. 4 according to another embodiment of the present disclosure.

[0181] 1a and 1b show schematic diagrams of an aerosol generation system according to one embodiment of the present disclosure. The aerosol generation system comprises a cartridge 10 in a use configuration received within an aerosol generating device 60. The aerosol generation system is portable and has a size comparable to that of a conventional cigar or cigarette.

[0182] Figures 2a, 2b, and 2c show schematic diagrams of cartridge 10 of Figures 1a and 1b. Cartridge 10 has a mouth end and a connection end opposite the mouth end. The connection end is configured for connection of cartridge 10 to an aerosol generation device 60, as described in more detail below.

[0183] The cartridge 10 includes an outer housing 36 formed from a moldable plastic material, such as polypropylene. The outer housing 36 defines a mouth-end opening 38 at the mouth end of the cartridge 10. The outer width of the outer housing 36 is greater at the mouth end of the cartridge 10 than at the connecting end, where they are connected by a shoulder 37. This arrangement allows the connecting end of the cartridge 10 to be received within a cavity 64 of the aerosol generation device 60, with the shoulder 37 positioning the cartridge 10 correctly within the device. This also allows the mouth end of the cartridge 10 to conform to the exterior shape of the aerosol generation device 60, allowing the mouth end of the cartridge 10 to remain outside of the aerosol generation device 60.

[0184] Cartridge 10 further includes a susceptor assembly 12 mounted within a susceptor element holder 14 .

[0185] The susceptor assembly 12 is described in more detail below.

[0186] The susceptor element holder 14 comprises a tubular body formed from a moldable plastic material, such as polypropylene. The tubular body of the susceptor element holder 14 comprises a sidewall defining an interior passage 26 having an open end and a central longitudinal axis. A pair of openings 28 extend through the sidewall on opposite sides of the tubular susceptor element holder 14. The openings 28 are centrally disposed along the length of the susceptor element holder 14. The susceptor element holder 14 further comprises a base 30 partially closing one end of the interior passage 26. The base 30 comprises a plurality of air inlets 32 that allow air to be drawn into the interior passage 26 through the partially closed end.

[0187] The outer housing 36 forms a first portion of the cartridge 10, and the susceptor assembly 12 and susceptor element holder 14 form a second portion of the cartridge 10. The second portion of the cartridge is slidable relative to the first portion of the cartridge between a storage configuration, as shown in Figures 2a and 2b, and a use configuration, as shown in Figure 2c. The susceptor assembly 12 and susceptor element holder 14 are located toward the connecting end of the cartridge 10.

[0188] A liquid reservoir 40 is defined within the cartridge 10 for holding a liquid aerosol-forming substrate 42. The liquid reservoir 40 is divided into two portions: a first portion 44 and a second portion 46. The first portion 44 is located toward the mouth end of the outer housing 36 and includes an annular space defined by the outer housing 36. The annular space has an internal passageway 48 extending between the mouth end opening 38 and the open end of the internal passageway 26 of the susceptor element holder 14. The second portion 46 of the liquid reservoir 40 is located toward the connecting end of the outer housing 36 and includes an annular space defined between the inner surface of the outer housing 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 housing 36. The seal 50 provides a fluid-tight seal between the susceptor element holder 14 and the outer housing 36.

[0189] The susceptor assembly 12 is shown in more detail in Figures 3a, 3b, 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 and second susceptor elements 16, 18. The first and second susceptor elements 16, 18 are substantially identical and comprise sintered meshes formed from filaments of SAE 410 stainless steel, a ferritic stainless steel. The wicking element 20 comprises a body of porous rayon filaments.

[0190] The first and second susceptor elements 16, 18, and the suction element 20 each form a substantially rectangular sheet. The suction element 20 is disposed between the first and second susceptor elements 16, 18, which are disposed opposite each other and centrally relative to the suction element 20. The suction element 20 has a length substantially equal to the lengths of the first and second susceptor elements 16, 18 and a width greater than the widths of the first and second susceptor elements 16, 18. Two outer edge portions 22 of the suction element 20 are not covered by the first and second susceptor elements 16, 18. As a result, the susceptor assembly 12 has a pair of attachment regions 22 formed by the uncovered edge portions of the suction element 20. The susceptor assembly 12 also includes a heating region 24 formed by a central region including the first susceptor element 16 and the second susceptor element 18, and a central portion of the suction element 20 between the first susceptor element 16 and the second susceptor element 18.

[0191] The suction element 20 is configured to supply a 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 region 24 is configured to be heatable by penetration of an alternating magnetic field to vaporize the aerosol-forming substrate supplied by the suction element 20 to the susceptor elements 16, 18.

[0192] The pair of mounting areas 22 are configured to extend into the liquid reservoir 40 of the cartridge 10 and convey 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 areas 22 are also configured to contact the susceptor element holder 14, which enables the susceptor element holder 14 to support the susceptor assembly 12 in place within the cartridge 10.

[0193] The heating regions 24 of the susceptor assembly are disposed entirely within the interior passage 26 of the susceptor element holder 14, and each of the mounting regions 22 extends through one of the openings 28 in the sidewall of the susceptor element holder 14. The openings 28 in the sidewall of the susceptor element holder 14 are sized to receive the susceptor assembly 12 with a friction fit, thereby securing the susceptor assembly within 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.

[0194] The susceptor element holder 14 further includes a pair of piercing elements 34 extending from the outer surface of the sidewall toward an open end of the susceptor element holder 14 opposite the end partially closed by the base 30. The openings 28 in the sidewall of the susceptor element holder 14 are disposed between the piercing elements 34 around the circumference of the sidewall such that the piercing elements 34 are offset by approximately 90 degrees from the openings 28 around the circumference of the sidewall of the tubular susceptor element. Each of the piercing elements 34 includes a spike pointing toward the open end of the susceptor element holder 14.

[0195] An air passageway is formed through the cartridge 10 by the internal passageway 26 of the susceptor element holder 14 and the internal passageway 48 through the first portion 44 of the liquid reservoir 40. The air passageway extends from the air inlet 32 ​​in the base 30 of the susceptor element holder 14, through the internal passageway 26 of the susceptor element holder 14, and through the internal passageway 48 of the first portion 44 of the liquid reservoir 40 to the mouth end opening 38. The air passageway allows air to be drawn through the cartridge 10 from the connection end to the mouth end.

[0196] When the cartridge is in the storage configuration, as shown in Figures 2a and 2b, the base 30 of the susceptor element holder 14 extends outside the outer housing 36. The first and second portions 44, 46 of the liquid reservoir 40 are fluidly separated from one another by an aluminum foil seal 52, and the piercing element 34 of the susceptor element holder 14 is spaced from the seal 52 toward the connecting end of the cartridge 10. In this configuration, the liquid aerosol-forming substrate 42 is retained within the first portion 44 of the liquid reservoir 40 and separated from the second portion 46 of the liquid reservoir 40 and the susceptor assembly 12 by the seal 52.

[0197] In the use configuration, as shown in FIG. 2c, the susceptor element holder 14 and 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 on the base 30 of the susceptor element holder 14 slides over the inner surface of the outer housing 36, establishing a fluid-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, allowing 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, exposing the susceptor assembly 12 to the liquid aerosol-forming substrate 42.

[0198] In the use configuration, the attachment region 22 of the draw element 20, which extends into the second portion 46 of the liquid reservoir 40, can 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. As a result, in the use configuration, the first susceptor element and the second susceptor element are supplied with the liquid aerosol-forming substrate 42, and the cartridge 10 is ready for use to generate an aerosol by heating the liquid aerosol-forming substrate 42.

[0199] 1a and 1b, the aerosol generating device 60 includes a generally cylindrical housing 62 having a connecting end and a distal end opposite the connecting end. A cavity 64 for receiving the connecting end of the cartridge 10 is located at the connecting 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 allow ambient air to be drawn into the cavity 64 at the base.

[0200] The device 60 further comprises a power supply circuit 66. The power supply circuit 66 includes an inductor coil 68, a controller 70, and a power source 72. The power source 72 comprises a rechargeable lithium iron phosphate battery having a DC supply voltage of 3.2 volts, which is rechargeable via an electrical connector (not shown) at the distal end of the device. The controller 70 is connected to the power source 72 and the inductor coil 68, such 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.

[0201] The inductor coil 68 comprises a helical coil that surrounds the cavity 64. When the cartridge 10 is received within the cavity 64, the first susceptor element 16 and the second susceptor element 18 are also surrounded by the inductor coil 68. When the cartridge 10 is received in the cavity 64, the inductor coil 68 is configured such that when an alternating current is supplied to the inductor coil 68, the inductor coil 68 generates an alternating magnetic field within the cavity 64 that penetrates the first susceptor element 16 and the second susceptor element 18.

[0202] The aerosol generating device 60 further includes 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.

[0203] In operation, when a user draws on mouth-end opening 38 of cartridge 10, ambient air is drawn into the base of cavity 64 through air inlet 65, as shown by the arrows in FIG. 1b, and into cartridge 10 through air inlet 32 ​​in base 30 of cartridge 10. Ambient air flows through cartridge 10 from base 30 to mouth-end opening 38 through the air passages and across susceptor assembly 12.

[0204] A controller 70 controls the supply of power from a power supply 72 to the inductor coil 68 when the system is activated. The controller 72 includes a puff detector in the form of an airflow sensor (not shown), and the controller 72 supplies power to the inductor coil 68 when a puff on the user's cartridge 10 is detected by the puff detector.

[0205] 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 and second susceptor elements 16 and 18, causing the first and second susceptor elements 16 and 18 to heat. A liquid aerosol-forming substrate in the second portion 44 of the liquid reservoir 40 is supplied to the first and second susceptor elements 16 and 18 by the suction element 20. The liquid aerosol-forming substrate supplied to the first and second susceptor elements 16 and 18 is heated, and volatile compounds from the heated aerosol-forming substrate are released into the air passage of the cartridge 10, which cools and forms an aerosol. The aerosol is entrained in air drawn through the air passage of the cartridge 10 and drawn out of the cartridge 10 at the mouth-end opening 38 for inhalation by the user.

[0206] 4 is a schematic block diagram illustrating a power supply circuit 66 according to an embodiment of the present disclosure for the aerosol generating device 60 of FIGS. 1a and 1b. 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 this example, the microcontroller 70 is mounted on the same printed circuit board (not shown) together with other electronic components and the heater module 74, although it will be appreciated that the heater module 74 could be provided on a separate, dedicated printed circuit board.

[0207] 1a and 1b, a microcontroller 70 is provided to control power delivered to a heater module 74, and specifically to the induction coil 68, which is inductively coupled to the first and second susceptor elements 16, 18 in the cartridge 10 when the cartridge 10 is coupled with the aerosol generating device 60. The microcontroller 70 is further provided 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, these other electronic components may include sensors, a user interface such as an LED or LCD screen for displaying information to a user and a switch for activating the aerosol generating device 60, a means for providing a data connection with an external device, and a charging circuit for recharging the battery 72.

[0208] In this example, a single microcontroller 70 is provided to control all features of the aerosol generating device 60. However, it should be appreciated that in some embodiments, several microcontrollers may be provided, with each microcontroller controlling a different feature of the aerosol generating device 60. For example, a first microcontroller may be provided to control the 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 a heater module with its own microcontroller is that it can be programmed with its own firmware to control the heating process and does not need to include firmware related to heating in other components, which may help make the heater module reusable in different devices. This may allow the heater module to be a stand-alone unit or module that can be incorporated into a variety of different devices.

[0209] As discussed in more detail below with reference to FIG. 5 , the heater module 74 includes a drive circuit (not shown in FIG. 4 ) for driving the induction coil 68 to heat the first susceptor element 16 and the second susceptor element 18 in the cartridge 10. The heater module 74 also includes a DC / AC voltage converter (not shown in FIG. 4 ) connected to the drive circuit and converting a DC voltage supplied to the drive circuit into an AC voltage to generate an alternating current in the induction coil 68, which in turn causes the induction coil 68 to generate an alternating current or alternating magnetic field. In this embodiment, the induction coil 68 is part of the DC / AC voltage converter. This arrangement helps reduce the number of electrical components required. However, it will be appreciated that the induction coil 68 could be separate from the DC / AC voltage converter, although this may require additional components to generate the AC voltage. The DC / AC voltage converter also includes a matching network (not shown in FIG. 4) configured to operate with low ohmic loads, which helps match the output impedance of the DC / AC converter to the load represented by the resistive losses of the induction coil and the apparent resistance of the susceptor elements 16, 18.

[0210] The power supply circuit 66 receives a DC supply voltage V from a battery 72. supplyand outputting a constant voltage of 2.95 volts at a voltage converter output 77. The voltage converter output 77 is connected to and provides a voltage input to the heater module 74. The output voltage from the DC / DC voltage converter 76 thus constitutes a 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 to provide a predetermined heating performance based on the specific components of the heater module. Of course, 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 is set, significant changes to the heater module input voltage Vin will change the power delivered to the induction coil and may lead to undesirable fluctuations in heating performance. Furthermore, some component parameters of the heater module 74 are sensitive to the input voltage, and changing the heater module input voltage Vin may lead to instability. Thus, the DC / DC voltage converter 76 helps reduce variability and improve stability by providing a constant heater module input voltage Vin. For clarity, the DC / DC voltage converter 76 is shown as a separate component in this example, but may also be part of the heater module 74.

[0211] The power supply circuit 66 of FIG. 4 in the aerosol generating device 60 of FIGS. 1a and 1b converts the 3.2-volt DC supply voltage of the lithium iron phosphate battery 72 to a constant heater module input voltage of 2.95 volts. In this case, the DC / DC voltage converter 76 helps maintain a constant heater module input voltage Vin, but the heater module 74 may function relatively normally using the 3.2-volt supply from the lithium iron phosphate battery 72 without the DC / DC voltage converter 76 because this supply voltage is not significantly different from the 2.95-volt heater module input voltage. However, it should be appreciated that the heater module 74 can be used in different aerosol generating devices using batteries with different battery chemistries. For example, the aerosol generating device 60 of FIGS. 1a and 1b could use a lithium nickel manganese cobalt oxide battery with a 4.2-volt DC supply voltage. In this case, the DC / DC voltage converter 76 allows the heater module 74 to operate directly without converting this higher DC supply voltage to 2.95 volts using the DC / DC voltage converter 76, in a manner similar to how the heater module 74 would operate using the lithium iron phosphate battery 72. In effect, the DC / DC voltage converter 76 is configured to accept a range of DC supply voltages and output a constant heater module input voltage. Thus, the DC / DC voltage converter 76 of the heater module 74 allows for the use of different types of batteries with a range of DC supply voltages.

[0212] FIG. 5 shows a portion of the power supply circuit 66 of FIG. 4 in more detail, specifically the heater module 74 of FIG. 4. The circuit of FIG. 5 is powered by the heater module input voltage Vin received at point X in FIG. 5, i.e., the output voltage 77 from the DC / DC voltage converter 76 of FIG. 4. The heater module 74 includes a transistor switch Q1 and a first inductor L1 that act as a drive circuit for driving the induction coil 68 and the DC / AC voltage converter. The transistor switch Q1 includes a field effect transistor (FET), e.g., a metal oxide semiconductor field effect transistor (MOSFET), and the first inductor L1 includes a radio frequency choke. The heater module input voltage Vin is supplied 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 radio frequencies that may be present at the input X from entering the circuit. The gate G of the transistor switch Q1 is connected to the microcontroller 70 of Figure 4 and receives a switching signal from the microcontroller 70 to turn the transistor switch Q1 on and off. The switching signal is a square wave with a substantially 50% duty cycle.

[0213] The heater module 74 further 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 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 passed to the transistor switch Q1 into an AC voltage across an equivalent resistance R4. The equivalent resistance R4 is a function of the ohmic resistance R of the second inductor L2 connected in series with the apparent ohmic resistance Ra of the susceptor elements 16, 18. coil Resistor R4 is shown in dashed outline in Figure 5 to indicate that it is not an actual resistor in the circuit, but rather the equivalent resistance of second inductor L2 and susceptor elements 16, 18.

[0214] Together, the first inductor L1, the transistor switch Q1, the first capacitor C1, the second inductor L2, and the second capacitor C2 form a Class-E power amplifier. The general operating principles of Class-E power amplifiers are known and described in detail in the article "Class-E RF Power Amplifiers", by Nathan O. Sokal, published in the bimonthly magazine QEX, edition January / February 10, 2001, pages 9-20, of the American Radio Relay League (ARRL), Newington, CT, USA, and therefore will not be discussed further herein.

[0215] Using a Class E amplifier to power the second inductor L2 has been found to be very efficient. This is because, due to the circuit configuration, there is no current flowing through the transistor switch Q1 at the same time that there is a voltage across the transistor switch Q1. As a result, virtually no energy is dissipated in the transistor switch Q1, and instead, virtually all of the power is delivered to the load equivalent resistor R4. Furthermore, the first capacitor C1 and the second inductor L2 form a series resonant circuit tuned to the switching frequency of the switching signal. The first capacitor C1 and the second inductor L2 act as a bandpass filter, allowing AC voltage signals to be delivered to the load equivalent resistor R4 only at the desired operating frequency of the second inductor L2. This means that power is delivered to the load equivalent resistor R4 only at the switching frequency of the switching signal, and any harmonic frequencies are significantly suppressed, further improving efficiency.

[0216] Additionally, the second inductor L2 and the capacitors C1 and C2 form an LC load or matching network configured to operate at a low ohmic load and serve to match the output impedance of the DC / AC converter to the load equivalent resistance R4. Specifically, 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 relative to the inductor L2, which is desirable for heating the aerosol-forming substrate.

[0217] The heater module 74 includes relatively few components compared to other power supply circuits for the aerosol generator, and therefore the printed circuit board area required to mount these components can be kept small, which helps reduce the overall size of the aerosol generator 60. Moreover, the use of the second inductor L2 in the DC / AC conversion further reduces the number of components.

[0218] 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, heating the susceptor elements 16, 18. As the susceptor elements 16, 18 heat during operation, the liquid aerosol-forming substrate supplied from the liquid reservoir 40 to the susceptor elements 16, 18 via the liquid transfer element 20 is vaporized.

[0219] The inventors have recognized that the apparent resistance Ra of the susceptor elements 16, 18 remains substantially constant while the liquid aerosol-forming substrate is supplied to the susceptor elements 16, 18 and the liquid aerosol-forming substrate is vaporized. However, if the supply of liquid aerosol-forming substrate to the susceptor elements 16, 18 is reduced or stopped, the apparent resistance Ra of the susceptor elements 16, 18 increases as the liquid reservoir is depleted, increasing the equivalent resistance R4 and decreasing the DC current IDC drawn by the heater module 74 at a constant voltage.

[0220] The circuit of FIG. 5 further comprises two sensor circuits: a current sensor circuit 80 and a voltage sensor circuit 82 for determining the equivalent resistance Re or the equivalent conductance G4 of the equivalent resistance R4.

[0221] The current sensor circuit 80 includes a current sensor in the form of a resistor R3 having a known value. Resistor R3 is connected in series between point X (which receives the heater module input voltage Vin) and the first inductor L1. Thus, during operation, the DC current IDC passing through resistor R3 is substantially the same as the current drawn by the heater module 74. As discussed above, the circuit of FIG. 5 is powered by the output voltage from the DC / DC voltage converter 76 of FIG. 4. Thus, the DC current IDC passing through resistor R3 is equal to the DC current supplied by the DC / DC voltage converter. Resistor R3 has an appropriately low resistance value to help reduce resistive losses.

[0222] The current sensor circuit 80 further includes a differential amplifier 84 having two inputs 84a and 84b connected across resistor R3 and thus receiving a voltage signal from both sides of resistor R3. The differential amplifier 84 has an output 84c that outputs a voltage proportional to the difference between the voltages received at inputs 84a and 84b, i.e., the voltage drop VR3 across resistor R3. The output 84c of the differential amplifier 84 is connected to an analog-to-digital converter (ADC) input of a microcontroller (MCU), in this embodiment, the microcontroller 70 of FIG. 4. Thus, based on the signal received from the output 84c of the differential amplifier 84, the microcontroller 70 is configured to determine the voltage drop VR3 across resistor R3. Because resistor R3 has a known value, the DC current IDC through resistor R3 supplied to the heater module 74 can be determined by the microcontroller 70 through application of Ohm's Law, as shown in equation (1):

[0223] [Formula 1] I DC =V R3 / R3 (1)

[0224] The voltage sensor circuit 82 includes a first resistor R1 and a second resistor R2 connected in series between point X, FIG. 5, where the heater module input voltage Vin is received, and electrical ground. Resistors R1 and R2 form a voltage or potential divider and have equal resistance values ​​so that the voltage at point Y between resistors R1 and R2 is equal to half the heater module input voltage Vin. Point Y is connected to an analog-to-digital converter (ADC) input of a microcontroller (MCU), i.e., microcontroller 70, FIG. 4, to provide the microcontroller 70 with a voltage signal corresponding to the voltage at point Y. This allows the microcontroller 70 to determine the heater module input voltage Vin by doubling the voltage signal received from point Y. Naturally, other resistance values ​​can be used for resistors R1 and R2, but this would require 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 voltage divider.

[0225] As mentioned above, the heater module input voltage Vin corresponds to a constant voltage output from the DC / DC voltage converter 76 of FIG. 4, so the voltage sensor circuit 82 is optional. Therefore, the heater module input voltage Vin is already known and constant, and therefore can 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 ensure it is the same as that stored in memory. The provision of the voltage sensor circuit 82 eliminates the need to store the heater module input voltage Vin in memory, thereby simplifying the programming of the microcontroller 70.

[0226] As discussed above, a Class E power amplifier has been found to be a highly efficient means for transferring power to the load equivalent resistor R4. As a result, the DC current I through resistor R3 represents the current supplied to the load equivalent resistor R4. Furthermore, the resistance of resistor R3 is relatively small, and therefore the voltage drop across resistor R3 is substantially negligible. Therefore, the value of the load equivalent resistor R4 can be determined by the microcontroller 70 by application of Ohm's Law, as shown in equation (2).

[0227] [Formula 2] R4=V in / I DC (2)

[0228] Equation (2) above can be rewritten to give the equivalent conductance G4 of the load equivalent resistance R4 as shown in equation (3) below:

[0229] [Formula 3] G4=I DC / V in (3)

[0230] The equivalent conductance G4 is the reciprocal of the equivalent resistance R4. An advantage of determining the equivalent conductance G4 according to equation (3) is that when the voltage Vin is constant, the conductance is indicative of, or directly related to, the DC current IDC, which in this case is provided by the DC / DC voltage converter 76 of FIG. 4. Thus, 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. As a result, 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.

[0231] FIG. 6 illustrates a flow diagram of a simplified method of operating power supply circuit 66 according to an embodiment of the present disclosure.

[0232] In a first step 101, the microcontroller 70 is configured to control switching signals to turn the transistor switch Q1 on and off to control the current and voltage between the power supply 72 and the inductor coil L2.

[0233] 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 is also configured to measure the heater module input voltage Vin by multiplying the voltage signal received from the voltage sensor circuit 82 by two.

[0234] 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.

[0235] In a fourth step 104, the microcontroller 70 is configured to compare the determined equivalent resistance R4 against a dry susceptor threshold value stored in the memory of the microcontroller 70.

[0236] In a fifth step 105, if the microcontroller 70 determines that the determined equivalent resistance R4 is less than or equal to the dry susceptor threshold, the microcontroller 70 is configured to determine that the susceptor elements 16, 18 are being supplied with a liquid aerosol-forming substrate and is configured to return to the first step 101.

[0237] 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 being supplied with liquid aerosol-forming substrate and to notify a user that the susceptor elements are not being supplied with enough liquid aerosol-forming substrate. In this embodiment, the notification comprises the microcontroller 70 illuminating a light-emitting diode (not shown).

[0238] FIG. 7 shows a flow diagram of a simplified method of operating power supply circuit 66 according to another embodiment of the present disclosure.

[0239] In a first step 101, the microcontroller 70 is configured to control switching signals to turn the transistor switch Q1 on and off to control the current and voltage between the power supply 72 and the inductor coil L2.

[0240] 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 .

[0241] In a third step 104, the microcontroller is configured to compare the measured current supplied by the DC / DC voltage converter 76 against a dry susceptor threshold 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.

[0242] 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 being supplied with a liquid aerosol-forming substrate and is configured to return to the first step 101.

[0243] 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 being supplied with liquid aerosol-forming substrate and to notify a user that the susceptor elements are not being supplied with enough liquid aerosol-forming substrate. In this embodiment, the notification comprises the microcontroller 70 illuminating a light-emitting diode (not shown).

[0244] In a sixth step 107, 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 control a switching signal to change the transistor switch to prevent current and voltage between the power supply 72 and the inductor coil L2.

[0245] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are understood to be modified in all instances by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number A is understood as A ± {5%}. Within this context, the number A may be considered to include values ​​that are within the common standard error for measurement of the property it modifies. In some instances, as used in the appended claims, the number A may deviate by the percentages recited above, provided that the amount by which A deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 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 the liquid aerosol-forming substrate supplied to the susceptor element; Power supply and A controller; wherein the controller: 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 against a dry susceptor threshold; and determining whether the liquid aerosol-forming substrate is being supplied to the susceptor element based on the comparison; A power supply circuit configured as follows.

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

3. 3. The power supply circuit of claim 1, wherein the controller is further configured to prevent the current from being supplied from the power source to the inductor coil when it is determined that the liquid aerosol-forming substrate is not being supplied to the susceptor element.

4. 4. The power supply circuit of claim 1, wherein the controller is configured to control at least one of the current and the voltage from the power source to the inductor coil, thereby supplying between about 6 watts and about 12 watts of power to the inductor coil, and optionally supplying between about 8 watts and about 10 watts to the inductor coil.

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

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

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

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

10. The power supply circuit of claim 9, wherein the dry susceptor threshold is 0.95 siemens or greater, and optionally from about 0.70 siemens to about 0.95 siemens.

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

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

13. 1. 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, the aerosol generating device comprising: 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; Power supply and a controller, controlling at least one of a current and a voltage between the power source and the inductor coil; comparing at least one of the current and the voltage between the power supply and the inductor coil to a dry susceptor threshold; and determining whether the liquid aerosol-forming substrate is being supplied to the susceptor element based on the comparison; a controller configured to An aerosol generating device comprising a power supply circuit comprising:

14. 1. An aerosol generating system comprising: A cartridge, a susceptor element; a liquid aerosol-forming substrate supplied to the susceptor element; a cartridge comprising: an aerosol generating device connectable to the cartridge and 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 comprising: 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; Power supply and a controller, controlling at least one of a current and a voltage between the power source and the inductor coil; comparing at least one of the current and the voltage between the power supply and the inductor coil to a dry susceptor threshold; determining whether the liquid aerosol-forming substrate is being supplied to the susceptor element based on the comparison; a controller configured to: an aerosol generating device comprising a power supply circuit comprising: An aerosol generating system comprising:

15. 1. A method of operating an aerosol generating device, the aerosol generating device comprising a power source 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 the current and the voltage between the power supply and the inductor coil to a dry susceptor threshold; determining whether the liquid aerosol-forming substrate is being supplied to the susceptor element based on the comparison; and A method comprising:

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