Aerosol generating apparatus and method of operating same

Abstract

A method of operating a heat-not-burn, HNB, aerosol-generating apparatus (1). The HNB aerosol-generating apparatus comprising a heating element (112, 312) and a measurement resistor (108, 306) having a predetermined resistance electrically connected in series. The method comprises: applying, by a power supply (102, 302), an electrical signal across the heating element (112, 312) and the measurement resistor (108, 306); determining, based on a measurement of the applied electrical signal, an instantaneous power consumption of the heating element (112, 312); determining, using the instantaneous power consumption of the heating element (112, 312), an ON proportion of a time period, such that, when the heating element is activated for the ON proportion of the time period, a target average power consumption by the heating element over the time period is achieved; and applying the supply voltage, by the power supply (102, 302), across the heating element (112, 312) for the ON proportion of the time period to achieve the target average power consumption.

Description

FIELD

[0001] The present disclosure relates to an aerosol generating apparatus and a method of operating the same.BACKGROUND

[0002] A typical heat-not-burn, HNB, aerosol generating apparatus may comprise a power supply, a heating element that is driven by the power supply, an aerosol precursor, which in use is aerosolised by the aerosol generating unit to generate an aerosol, and a delivery system for delivery of the aerosol to a user.

[0003] A drawback with known HNB aerosol generating apparatuses is that the power consumption of the heating element may evolve over time and / or vary between nominally identical HNB aerosol generating apparatuses. This may result in an inconsistent aerosol generation and consequently an inconsistent user experience for a user of the HNB aerosol generating apparatus.

[0004] In spite of the effort already invested in the development of aerosol generating apparatuses / systems further improvements are desirable.SUMMARY

[0005] In a first aspect, the present disclosure provides a method of operating a heat-not-burn, HNB, aerosol generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a measurement resistor having a predetermined resistance electrically connected in series. The method comprises: applying, by a power supply, an electrical signal across the heating element and the measurement resistor; determining, based on a measurement of the applied electrical signal an instantaneous power consumption of the heating element; determining, using the instantaneous power consumption of the heating element, an ON proportion of a time period, such that, when the heating element is activated for the ON proportion of the time period, a target average power consumption by the heating element over the time period is achieved; and applying a supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption.

[0006] In some embodiments, there may be provided a method of operating a heat-not-burn, HNB, aerosol generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a measurement resistor having a predetermined resistance electrically connected in series to define a potential divider. The method comprises: applying a supply voltage, by a power supply, across the resistor and the heating element for an initial period; measuring a midpoint voltage between the measurement resistor and the heating element; determining an instantaneous power consumption of the heating element based on the measured midpoint voltage; determining, using the instantaneous power consumption of the heating element, an ON proportion of a time period, such that, when the heating element is activated for the ON proportion of the time period a target average power consumption by the heating element over the time period is achieved; and applying the supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption.

[0007] By operating the HNB aerosol generating apparatus in this manner, it may be possible to ensure that the average power consumption of the heating element is consistent. In this manner, the HNB aerosol generating apparatus may be able to generate aerosol under activation of the heating element in a consistent manner, thereby providing the user of the HNB aerosol generating apparatus with a consistent user experience.

[0008] In some examples, the heating element may be a resistive heating element. For example, the heating element may be a heater that is heated as a result of the heater's resistance to electrical current passing through the heater.

[0009] In some examples, the resistor having a predetermined resistance may be referred to interchangeably and without limitation, as a measurement resistor or a sense resistor.

[0010] In some examples, the power supply may be configured to provide a fixed voltage, said fixed voltage being the supply voltage. Alternatively, the power supply may be configured to provide a variable voltage, with the supply voltage being a selected voltage from within an operating range of the power supply. In some examples, on demand, or in response to one or more predetermined criteria being satisfied, the power supply may be configured to boost the voltage of the supply voltage to a higher level, for example, to compensate for an instantaneous drop or dip in the temperature of the heating element. For example, by inhaling and drawing air through the HNB aerosol generating apparatus, the user may draw air over a surface of the heating element, thereby cooling the heating element. This may cause a decrease in the efficiency of any aerosol generation by the heating element that may be compensated for by boosting a power supply to the heating element to a relatively higher level.

[0011] In some examples, the midpoint voltage may be understood as being a midpoint (or output) voltage of the potential divider. Accordingly, an instantaneous resistance of the heating element may be determinable by the skilled person using known analysis techniques relating to potential dividers.

[0012] In some examples, the instantaneous power consumption of the heating element may be determined, at least in part, by inferring the instantaneous resistance of the heating element from the values of the predetermined resistance, the applied supply voltage, and the measured midpoint voltage.

[0013] In some examples, applying the supply voltage across the resistor and the heating element may comprise applying a constant supply voltage for the initial period.

[0014] In some examples, applying the supply voltage across the heating element to achieve the target average power consumption may comprise applying the supply voltage with a top-hat, or step profile, wherein the top-hat or step may be defined with an upper voltage value equal to the supply voltage applied during the initial period, and a lower voltage value equal to 0 V.

[0015] In some examples, the initial period may be 15 ms or less, 10 ms or less, 5 ms or less, or 2 ms or less. Alternatively, the initial period may be 1 ms or more, 2 ms or more, 5 ms or more, or 10 ms or more. Alternatively, the initial period may be between 1 and 15 ms, 1 and 10 ms, 1 and 5 ms, 1 and 2 ms, 2 and 15 ms, 2 and 10 ms, 2 and 5 ms, 5 and 15 ms, 5 and 10 ms, or 10 and 15 ms.

[0016] In a particular example, the initial period is 5 ms. In some examples, the measuring of the midpoint voltage, and determining the instantaneous power consumption and the ON proportion of the time period may be instantaneous, or at least substantially instantaneous (i.e., negligible in relation to the duration of the initial period). For example, the amount of time required to measure the midpoint voltage (or any other electrical property of the voltage / current) may be approximately 100 µs.

[0017] In some examples, the time period may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the time period may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the time period may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0018] In a particular example, the time period may be 20 ms, the first 5 ms of which may be the initial period.

[0019] In some examples, the initial period may be a part of the time period. In other words, the application of the supply voltage for the initial period, and the determination of the ON proportion of the time period for which the heating element needs to be activated to achieve the target average power consumption may be carried out at the beginning of the time period. For example, the voltage applied during the time period may be defined by a step profile. The step profile may be defined by an upper voltage value equal to the supply voltage that transitions to a lower voltage value equal to 0 V. The portion of the step profile defined by the upper voltage may comprise two parts, a first part that is the initial period, and a second part that is the remainder of the upper voltage portion between the initial period and the transition to the lower voltage value. The transition to the lower voltage value may occur at the end of the determined ON proportion of the time period.

[0020] In some embodiments, the method may be cyclically repeated during operation of the HNB aerosol-generating apparatus.

[0021] For example, the carrying out of the method may be cyclically repeated every 5 ms, 10 ms, 20 ms, 30 ms, 50 ms, or 100 ms. For example, the carrying out of the method may be cyclically repeated on a continuous basis such that there is no delay between consecutive time periods.

[0022] In a particular example, the method is cyclically repeated every 20 ms.

[0023] As the power consumption of the heating element impacts the generation of aerosol by the heating element (indirectly by impacting the temperature of the heating element), by keeping the time period (and the cyclical repetition period) short, relative to a user's perception, the user may not perceive variations in the quality of the aerosol generated and delivered to the user by the aerosol-generating apparatus. The quality of the aerosol may include one or more of a quantity, temperature, concentration, and / or consistency of an aerosol generated by the aerosol-generating apparatus.

[0024] In some embodiments, the resistor may be connected between the power supply and the heating element.

[0025] In this way, the midpoint voltage may be a representation of the voltage drop across the resistor.

[0026] Alternatively, the heating element may be connected between the power supply and the resistor. In such examples, the midpoint voltage may be a representation of the voltage drop across the heating element.

[0027] In some embodiments, the resistor may be switchably connected in series with the heating element such that the supply voltage is not applied across the resistor when applying the supply voltage across the heating element for the determined ON proportion of the time period to achieve the target average power consumption. For example, during at least part (and, in some examples, all) of the ON proportion of the time period, the measurement resistor may be bypassed. For the avoidance of doubt, power is applied across the heating element during both the initial period and the determined ON proportion of the time period. The determined ON proportion of the time period may be considered, in at least some examples, to be the amount of time (when considered in addition to the initial period) for which it is necessary to apply the supply voltage across the heating element in order to achieve the target average power consumption.

[0028] In this way, voltage consumption across the resistor may be limited only to the measurement period. In other words, power may only be dissipated through the resistor for sufficient time to determine the instantaneous power consumption of the heating element and the ON proportion of the time period for which the heating element needs to be activated to achieve the target average power consumption by the heating element over the time period.

[0029] In some embodiments, the HNB aerosol-generating apparatus may comprise a circuit connecting the power supply to the heating element. The circuit may comprise two circuit paths. The first circuit path may be switchably connectable path with the power supply and may comprise the resistor. The second circuit path may be switchably connectable path with the power supply and may be arranged to bypass the resistor. Applying the supply voltage across the resistor and the heating element may involve switchably connecting the first circuit path and switchably disconnecting the second circuit path. Applying the supply voltage across the heating element and not the resistor may involve switchably connecting the second circuit path and switchably disconnecting the first circuit path.

[0030] In this way, the resistor may be connected and disconnected from the power supply on an as needed basis for the purpose of measuring the midpoint voltage, determining the instantaneous power consumption of the heating element, and determining the ON proportion of the time period for which the heating element needs to be activated to achieve a target average power consumption by the heating element over the time period.

[0031] The resistor may be switchably connected to the power supply for some or all of the measurement period. In some examples, the resistor may be switchably connected only briefly, even instantaneously, during the measurement period before being disconnected to avoid unnecessary dissipation of power through the resistor.

[0032] In some embodiments, the first and / or second circuit paths may be switchably connected to the power supply by a respective field-effect transistor, FET, switch.

[0033] FET switches may be advantageous as their switching time can be significantly shorter than either the time period or the measurement period of the methods described herein. In other words, the switching time of the FET switches may be considered to be functionally instantaneous meaning that the switchable connections and disconnections of the first and / or second circuit paths does not impact the smoothness of the power / voltage delivery to the heating element, or at least the user's perception of the smoothness of the power / voltage delivery to the heating element.

[0034] In some examples, any one or more of the one or more FET switches may be a MOSFET switch. In some examples, any one or more of the one or more FET switches may be either a P-channel or a N-channel FET, or a P-channel or N-channel MOSFET.

[0035] In some examples, a circuit connecting the power supply to ground via the measurement resistor and the heating element may comprise one or more P-channel FET (or MOSFET) switches between the measurement resistor and the power supply and / or between the heating element and the power supply. In some examples, said circuit may further comprise one or more N-channel FET (or MOSFET switches) between the heating element and ground.

[0036] In some embodiments, the predetermined resistance may be within a predetermined range from a nominal resistance of the heating element.

[0037] The nominal resistance of the heating element may be understood to be a standard, expected or representative resistance of the heating element. For example, the nominal resistance may be an expected resistance provided by a manufacturer of the heating element when the heater is at room temperature. In some examples, the nominal resistance may be a midpoint of an expected operating resistance range provided by a manufacturer of the heating element, the expected operating resistance range being a range of possible resistance values for the resistance of the heating element that are within a manufacturing tolerance of the heating element.

[0038] In some examples, the nominal resistance of the heating element may be updated over time, for example, in response to a resistance of the heating element changing over time (e.g., due to operation of the heating element). For example, a resistance of the heating element at room temperature of the heating element may change over time, e.g., due to deterioration of one or more components of the heating element, or there may be a long-term gradual drift in the nominal resistance of the heating element that may be compensated for.

[0039] In some examples, the nominal resistance of the heating element may be 2 Ω or less, 1.8 Ω or less, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the nominal resistance of the heating element may be 0.2 Ω or more, 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 1.8 Ω or more. In some examples, the nominal resistance of the heating element may be between 0.2 and 2 Ω, 0.2 and 1.8 Ω, 0.2 and 1.5 Ω, 0.2 and 1 Ω, 0.2 and 0.5 Ω, 0.5 and 2 Ω, 0.5 and 1.8 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.8 Ω, 1 and 1.5 Ω, 1.5 and 2 Ω, 1.5 and 1.8 Ω, or 1.8 and 2 Ω.

[0040] In a particular example, the nominal resistance of the heating element may be between 0.2 and 1.8 Ω.

[0041] In a particular example, the nominal resistance of the heating element may be 1.1 ± 0.1 Ω.

[0042] In some examples, the measurement resistor may be a fixed resistance resistor. Alternatively, in some examples, the measurement resistor may be a variable resistor. The predetermined resistance may, in some examples, be varied to ensure that the predetermined resistance remains within the predetermined range from the nominal resistance of the heating element as the nominal resistance evolves over the lifetime of the heating element.

[0043] The predetermined resistance being within the predetermined range from the nominal resistance may be understood to mean that the difference between the predetermined resistance and the nominal resistance may be less than a predetermined percentage of the nominal resistance.

[0044] The predetermined percentage may, for example, be 100% or less, 75% or less, 50% or less, 25% or less, or 10% or less. The predetermined percentage may, for example, be 10% or more, 25% or more, 50% or more, 75% or more, or 100% or more. The predetermined percentage may, for example, be between 10 and 100%, 10 and 75 %, 10 and 50%, 10 and 25 %, 25 and 100%, 25 and 75%, 25 and 50%, 50 and 100%, 50 and 75%, or 75 and 100%.

[0045] Alternatively, the predetermined resistance being within the predetermined range from the nominal resistance may be understood to mean that the difference between the predetermined resistance and the nominal resistance may be less than a predetermined difference threshold.

[0046] The predetermined difference threshold may, for example, be 2 Ω or less, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the predetermined difference threshold may be 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 2 Ω or more. In some examples, the predetermined difference threshold may be between 0.5 and 2 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.5 Ω, or 1.5 and 2 Ω.

[0047] In some examples, the predetermined resistance of the resistor may be 2 Ω or less, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the predetermined resistance may be 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 2 Ω or more. In some examples, the predetermined resistance may be between 0.5 and 2 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.5 Ω, or 1.5 and 2 Ω.

[0048] In a particular example, the predetermined resistance may be 1.6 Ω.

[0049] By ensuring that the predetermined resistance of the measurement resistor is within a predetermined range from the nominal resistance of the heating element (i.e., that the predetermined resistance and nominal resistance are similar), a larger dynamic range of the midpoint voltage measurement is facilitated, thereby making the measurement of the midpoint voltage more sensitive to differences between the predetermined resistance and a resistance of the heating element.

[0050] In some embodiments, the method may further comprise measuring the supply voltage supplied across the measurement resistor and the heating element.

[0051] Alternatively, in some examples, the supply voltage may be a known supply voltage, or a voltage set by the user of the HNB aerosol-generating apparatus, or a voltage set by a control unit or processor of the HNB aerosol-generating apparatus.

[0052] In some embodiments, measuring the midpoint voltage may be carried out after a predetermined settling time has elapsed after beginning to apply the supply voltage across the heating element.

[0053] In some embodiments, measuring the supply voltage may be carried out after the predetermined settling time has elapsed after beginning to apply the supply voltage across the heating element.

[0054] When a voltage is applied across the heating element (e.g., at the commencement of the time period and / or at the commencement of the initial period), the supply voltage may drop as a result of the resistive load of the heating element. To ensure a more accurate control of the power consumption of the heating element (e.g., improving the accuracy of attaining the target average power consumption), it may be beneficial to wait for the supply voltage to drop and settle at a consistent "under-load" voltage level. The amount of time to wait for the supply voltage to drop and settle at the under-load voltage level is referred to herein as the settling time.

[0055] In some examples, the settling time may be a part of the initial period.

[0056] In some examples, the settling time may be 10 ms or less, 7 ms or less, 5 ms or less, or 2 ms or less. In some examples, the settling time may be 2 ms or more, 5 ms or more, 7 ms or more , or 10 ms or more. In some examples, the settling time may be between 2 and 10 ms, 2 and 7 ms, 2 and 5 ms, 5 and 10 ms, 5 and 7 ms, or 7 and 10 ms.

[0057] In a particular example, the settling time may be between 2 and 7 ms.

[0058] In a particular example, the settling time may be 5 ms. In some examples, the measuring of the midpoint voltage, and determining the instantaneous power consumption and the ON proportion of the time period may be instantaneous, or at least substantially instantaneous (i.e., negligible in relation to the settling time). For example, the amount of time required to measure the midpoint voltage (or any other electrical property of the voltage / current) may be approximately 100 µs.

[0059] In some embodiments, applying the supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption may involve: applying the supply voltage, by the power supply, across the heating element for a first continuous portion of the time period equal to the ON proportion; and not applying the supply voltage for a second continuous portion if the time period equal to the remainder of the time period.

[0060] In other words, the temporal profile of the supply voltage applied across the heating element may be defined by a step-down profile as described above.

[0061] In some embodiments, the method may further comprise: selecting an operation mode of the HNB aerosol-generating apparatus from amongst a plurality of operation modes. Each operation mode may require a respective power consumption. The target average power consumption may be a respective power consumption corresponding to the selected operation mode of the HNB aerosol-generating apparatus.

[0062] In some examples, the HNB aerosol-generating apparatus may be operable in a plurality of different operation modes. For example, the HNB aerosol-generating apparatus may be useable with a plurality of different precursors, each of which may be configured to generate an aerosol from the precursor upon the application of heat to a corresponding temperature. Each operating mode of the HNB aerosol-generating apparatus may therefore correspond to a respectively different target heating temperature that is suitable for activating a corresponding precursor to generate aerosol (e.g., for inhalation by the user). As such, each operating mode of the HNB aerosol-generating apparatus may correspond with a respectively different target average power consumption of the heating element in order to achieve the corresponding target heating temperature. Additionally or alternatively, heating a same precursor to one of a set of different temperatures may result in the generation of different quantities and / or concentrations of aerosol from the same precursor. In other words, a higher temperature may be used to deliver an aerosol that provides a user of the aerosol-generating apparatus with a more intense user experience (e.g., because the delivered aerosol is more potent, and / or generated in higher quantities and / or concentrations). As such, the plurality of different operation modes may correspond with respectively different target average power consumptions of the heating element in order to achieve a desired user experience for a user of the aerosol-generating apparatus.

[0063] In some embodiments, determining the instantaneous power consumption of the heating element may comprise: determining a voltage ratio between the supply voltage and the midpoint voltage; determining the instantaneous resistance of the heating element using the voltage ratio and the predetermined resistance; and determining the instantaneous power consumption of the heating element using the measured midpoint voltage and the determined instantaneous resistance of the heating element. The determined voltage ratio may be equal to a resistance ratio between the predetermined resistance and an instantaneous resistance of the heating element.

[0064] In some embodiments, determining the ON proportion of the time period may comprise: determining a ratio between the target average power consumption and the determined instantaneous power consumption; adjusting the ratio to account for electrical losses in a circuit comprising the power supply and the heating element; and applying the adjusted ratio to the time period to determine the ON proportion of the time period.

[0065] In this way, losses in the power delivered by the power supply may be accounted for such that the target average power consumption may be reliably and accurately achieved.

[0066] As an illustrative example, that is not intended to be limiting in the context of the present disclosure, if the adjusted ratio was indicative that the instantaneous power consumption of the heating element was double the target average power consumption, then the ON proportion of the time period would be determined to be half the total length of the time period. In other words, the ON proportion of the time period is determined in a manner that is inversely proportional to the ratio of the target average power consumption to the instantaneous power consumption.

[0067] In another aspect, there is provided a heat-not-burn, HNB, aerosol-generating apparatus comprising: a heating element configured to heat an aerosol precursor; a power supply configured to supply electrical current to the heating element; a measurement resistor having a predetermined resistance; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out the methods described herein. The heating element is heatable by flowing electrical current therethrough.

[0068] In another aspect there may be provided a computer-readable medium, or a computer program comprising logic and / or instructions that, when executed by a processor of a HNB aerosol-generating apparatus, cause the HNB aerosol-generating apparatus to carry out the methods described herein.

[0069] In some embodiments, there may be provided a method of operating a heat-not-burn, HNB, aerosol-generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a measurement resistor having a predetermined resistance electrically connected in series. The method comprises: supplying, by a power supply, a current through the resistor and the heating element; measuring the current passing through the resistor; determining an instantaneous power consumption of the heating element based on the measured current; determining, using the instantaneous power consumption of the heating element, an ON proportion of a time period such that, when the heating element is activated for the ON proportion of the time period a target average power consumption by the heating element over the time period is achieved; and applying a supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption.

[0070] In some examples, the supply voltage may be the same electrical supply as the current supplied by the power supply through the measurement resistor and the heating element.

[0071] By operating the HNB aerosol generating apparatus in this manner, it may be possible to ensure that the average power consumption of the heating element is consistent. In this manner, the HNB aerosol-generating apparatus may be able to generate aerosol under activation of the heating element in a consistent manner, thereby providing the user of the HNB aerosol generating apparatus with a consistent user experience.

[0072] In some examples, the heating element may be a resistive heating element. For example, the heating element may be a heater that is heated as a result of the heater's resistance to electrical current passing through the heater.

[0073] In some examples, the measurement resistor may be referred to interchangeably and without limitation, as a sense resistor.

[0074] In some examples, the power supply may be configured to provide a fixed current and / or voltage, said fixed current being the current supplied through the measurement resistor and the heating element, and / or said voltage being the supply voltage. Alternatively, the power supply may be configured to provide a variable voltage, with the supply voltage being a selected voltage from within an operating range of the power supply. Additionally or alternatively, the power supply may be configured to provide a variable current, with the current supplied through the measurement resistor and the heating element being a selected current form within an operating range of the power supply. In some examples, on demand, or in response to one or more predetermined criteria being satisfied, the power supply may be configured to boost the voltage of the supply voltage (or the current supplied through the resistor and the heating element) to a higher level, for example, to compensate for an instantaneous drop or dip in the temperature of the heating element. For example, by inhaling and drawing air through the HNB aerosol generating apparatus, the user may draw air over a surface of the heating element, thereby cooling the heating element. This may cause a decrease in the efficiency of any aerosol generation by the heating element that may be compensated for by boosting a power supply to the heating element to a relatively higher level.

[0075] In some examples, the instantaneous power consumption may be determined, at least in part, by inferring the instantaneous resistance of the heating element from the values of the supply voltage and the measured current.

[0076] In some examples, applying the supply voltage across the heating element to achieve the target average power consumption may comprise applying the supply voltage with a top-hat, or step profile, wherein the top-hat or step may be defined with an upper voltage value equal to the supply voltage applied during an initial period, and a lower voltage value equal to 0 V.

[0077] In some examples, the time period may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the time period may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the time period may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0078] In a particular example, the time period is 20 ms.

[0079] In some embodiments, the method may be cyclically repeated during operation of the HNB aerosol-generating apparatus.

[0080] For example, the carrying out of the method may be cyclically repeated every 5 ms, 10 ms, 20 ms, 30 ms, 50 ms, or 100 ms. For example, the carrying out of the method may be cyclically repeated on a continuous basis such that there is no delay between consecutive time periods.

[0081] In a particular example, the method is cyclically repeated every 20 ms.

[0082] As the power consumption of the heating impacts the generation of aerosol by the heating element (indirectly by impacting the temperature of the heating element), by keeping the time period (and the cyclical repetition period) short, relative to a user's perception, the user may not perceive variations in the quality of the aerosol generated and delivered to the user by the aerosol-generating apparatus. The quality of the aerosol may include one or more of a quantity, temperature, concentration, and / or consistency of an aerosol generated by the aerosol-generating apparatus.

[0083] In some embodiments, the predetermined resistance may be less than a nominal resistance of the heating element.

[0084] The nominal resistance of the heating element may be understood to be a standard, expected or representative resistance of the heating element. For example, the nominal resistance may be an expected resistance provided by a manufacturer of the heating element when the heater is at room temperature. In some examples, the nominal resistance may be a midpoint of an expected operating resistance range provided by a manufacturer of the heating element, the expecting operating resistance being a range of possible resistance values of the resistance of the heating element that are within a manufacturing tolerance of the heating element.

[0085] In some examples, the nominal resistance of the heating element may be updated over time, for example, in response to a resistance of the heating element changing over time (e.g., due to operation of the heating element). For example, a resistance of the heating element at room temperature heating element may change over time, e.g., due to deterioration of one or more components of the heating element, or there may be a long-term gradual drift in the nominal resistance of the heating element that may be compensated for.

[0086] In some examples, the nominal resistance of the heating element may be 2 Ω or less, 1.8 Ω or more, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the nominal resistance of the heating element may be 0.2 Ω or more, 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 1.8 Ω or more. In some examples, the nominal resistance of the heating element may be between 0.2 and 2 Ω, 0.2 and 1.8 Ω, 0.2 and 1.5 Ω, 0.2 and 1 Ω, 0.2 and 0.5 Ω, 0.5 and 2 Ω, 0.5 and 1.8 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.8 Ω, 1 and 1.5 Ω, 1.5 and 2 Ω, 1.5 and 1.8 Ω, or 1.8 and 2 Ω.

[0087] In a particular example, the nominal resistance of the heating element may be between 0.2 and 1.8 Ω.

[0088] In a particular example, the nominal resistance of the heating element may be 1.1 ± 0.1 Ω.

[0089] In some examples, the measurement resistor may be a fixed resistance resistor. Alternatively, in some examples, the measurement resistor may be a variable resistor. The predetermined resistance may, in some examples, be varied to ensure that the predetermined resistance remains lower than the nominal resistance of the heating element.

[0090] In some examples, the predetermined resistance may be at least 5 times less than the nominal resistance, at least 10 times less than the nominal resistance, at least 20 times less than the nominal resistance, at least 50 times less than the nominal resistance, at least 100 times less than the nominal resistance, at least 250 times less than the nominal resistance, or at least 500 times less than the nominal resistance.

[0091] In some embodiments, the predetermined resistance may be at least 10 times less than the nominal resistance.

[0092] In some embodiments, the predetermined resistance may be at least 100 times less than the nominal resistance.

[0093] In some examples, the predetermined resistance may be 100 mΩ or less, 50 mΩ or less, 10 mΩ or less, 5 mΩ or less, or 1 mΩ or less. In some examples, the predetermined resistance may be 1 mΩ or more, 5 mΩ or more, 10 mΩ or more, or 50 mΩ or more. In some examples, the predetermined resistance may be between 1 and 100 mΩ, between 1 and 50 mΩ, between 1 and 10 mΩ, between 1 and 5 mΩ, between 5 and 100 mΩ, between 5 and 50 mΩ, between 5 and 10 mΩ, between 10 and 100 mΩ, between 10 and 50 mΩ, or between 50 and 100 mΩ.

[0094] By ensuring that the predetermined resistance is less than the nominal resistance of the heating element (and, optionally, significantly less than the nominal resistance), it may be possible to facilitate a negligible power consumption by the measurement (or sense) resistor. In this way, it may be possible to assume that there is a negligible volage drop across the measurement (or sense) resistor, and therefore that all, or substantially all, of the supply voltage, at least in a practical sense, is supplied across the heating element.

[0095] In some embodiments, measuring the current passing through the measurement resistor may comprise using a current sense amplifier to measure the current.

[0096] A current sense amplifier may be suitable for use in the context of the methods described herein to measure the current passing through the resistor by amplifying a voltage drop across the measurement (or sense) resistor to a larger voltage thereby increasing the resolution and dynamic range of the current measurement.

[0097] In some examples, the current sense amplifier may have a gain functionality to implement a gain of the voltage drop across the measurement (or sense) resistor. In some examples the gain may be a fixed gain. Alternatively, the gain may be a variable gain that is adjustable by a user of the HNB aerosol generating apparatus, or by a control unit or processor of the HNB aerosol generating apparatus.

[0098] In some examples, the gain of the current sense amplifier may be 10 or more, 20 or more, 50 or more 100 or more, 250 or more, or 500 or more. In some examples, the gain of the current sense amplifier may be 500 or less, 250 or less, 100 or less, 50 or less, 20 or less, or 10 or less. In some examples, the gain of the current sense amplifier may be between 10 and 500, between 10 and 250, between 10 and 50, between 10 and 20, between 20 and 500, between 20 and 250, between 20 and 100, between 20 and 50, between 50 and 500, between 50 and 250, between 50 and 100, between 100 and 500, between 100 and 250, or between 250 and 500.

[0099] In a particular example, the gain of the current sense amplifier may be between 50 and 200. In a particular example, the gain of the current sense amplifier may be 50. In a particular example, the gain of the current sense amplifier may be 200.

[0100] In some embodiments, the method may further comprise measuring the supply voltage supplied across the measurement resistor and the heating element. Determining the instantaneous power consumption of the heating element may involve using the measured current and the measured supply voltage.

[0101] Alternatively, in some examples, the supply voltage may be a known supply voltage, or a voltage set by the user of the HNB aerosol-generating apparatus, or a voltage set by a control unit or processor of the HNB aerosol-generating apparatus.

[0102] In some embodiments, measuring the current may be carried out after a predetermined settling time has elapsed after beginning to apply the current through the measurement resistor and the heating element.

[0103] In some embodiments, measuring the supply voltage may be carried out after the predetermined settling time has elapsed after beginning to apply the current through the measurement resistor and the heating element.

[0104] When a voltage or current is applied across or through the heating element (e.g., at the commencement of the time period), the supply voltage / current may drop as a result of the resistive load of the heating element. In order to ensure a more accurate control of the power consumption of the heating element (e.g., improving the accuracy of attaining the target average power consumption), it may be beneficial to wait for the supply voltage / current to drop and settle at a consistent "under-load" voltage level. The amount of time to wait for the supply voltage / current to drop and settle at the under-load voltage level is referred to herein as the settling time.

[0105] In some examples, the settling time may be 10 ms or less, 7 ms or less, 5 ms or less, or 2 ms or less. In some examples, the settling time may be 2 ms or more, 5 ms or more, 7 ms or more , or 10 ms or more. In some examples, the settling time may be between 2 and 10 ms, 2 and 7 ms, 2 and 5 ms, 5 and 10 ms, 5 and 7 ms, or 7 and 10 ms.

[0106] In a particular example, the settling time may be between 2 and 7 ms.

[0107] In a particular example, the settling time may be 5 ms.

[0108] In some embodiments, the heating element may be switchably connected to the power supply.

[0109] In some examples, the heating element may be swithcably connected to the power supply by one or more field-effect, FET, switches.

[0110] FET switches may be advantageous as their switching time can be significantly shorter than either the time period or the measurement period of the methods described herein. In other words, the switching time of the FET switches may be considered to be functionally instantaneous meaning that the switchable connections and disconnections of the FET switches do not impact the smoothness of the power / voltage delivery to the heating element, or at least the user's perception of the smoothness of the power / voltage delivery to the heating element.

[0111] In some examples, any one or more of the one or more FET switches may be a MOSFET switch. In some examples, any one or more of the one or more FET switches may be either a P-channel or a N-channel FET, or a P-channel or N-channel MOSFET.

[0112] In some examples, a circuit connecting the power supply to ground via the measurement resistor and the heating element may comprise one or more P-channel FET (or MOSFET) switches between the measurement resistor and the power supply and / or between the heating element and the power supply. In some examples, said circuit may further comprise one or more N-channel FET (or MOSFET switches) between the heating element and ground.

[0113] In some embodiments, applying the supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption may involve: applying the supply voltage, by the power supply, across the heating element for a first continuous portion of the time period equal to the ON proportion; and preventing the supply of the supply voltage for a second, subsequent, continuous portion of the time period equal to the remainder of the time period.

[0114] In other words, the temporal profile of the supply voltage applied across the heating element may be defined by a step-down profile as described above.

[0115] In some embodiments, the method may further comprise: selecting an operation mode of the HNB aerosol-generating apparatus from amongst a plurality of operation modes. Each operation mode may require a respective power consumption. The target average power consumption may be a respective power consumption corresponding to the selected operation mode of the HNB aerosol-generating apparatus.

[0116] In some examples, the HNB aerosol-generating apparatus may be operable in a plurality of different operation modes. For example, the HNB aerosol-generating apparatus may be useable with a plurality of different precursors, each of which may be configured to generate an aerosol from the precursor upon the application of heat to a corresponding temperature. Each operating mode of the HNB aerosol-generating apparatus may therefore correspond to a respectively different target heating temperature that is suitable for activating a corresponding precursor to generate aerosol (e.g., for inhalation by the user). As such, each operating mode of the HNB aerosol-generating apparatus may correspond with a respectively different target average power consumption of the heating element in order to achieve the corresponding target heating temperature. Additionally or alternatively, heating a same precursor to one of a set of different temperatures may result in the generation of different quantities and / or concentrations of aerosol from the same precursor. In other words, a higher temperature may be used to deliver an aerosol that provides a user of the aerosol-generating apparatus with a more intense user experience (e.g., because the delivered aerosol is more potent, and / or generated in higher quantities and / or concentrations). As such, the plurality of different operation modes may correspond with respectively different target average power consumptions of the heating element in order to achieve a desired user experience for a user of the aerosol-generating apparatus.

[0117] In some embodiments, determining the instantaneous power consumption of the heating element may comprise: estimating a voltage drop across the heating element as being equal to the supply voltage; and determining the instantaneous power consumption of the heating element as the product of the voltage drop and the measured current.

[0118] In other words, in cases where the predetermined resistance of the measurement resistor is negligible relative to the instantaneous resistance of the heating element, it may be practically feasible to assume that all (or substantially all) of the power output by the power supply is depleted / consumed / dissipated by the heating element, and not by the measurement resistor. As such, the instantaneous power consumption of the heating element may be approximated using the standard relation that power consumption is equal to the product of the current flowing through a circuit element with the voltage drop across said circuit element.

[0119] In some embodiments, determining the ON proportion of the time period may comprise: determining a ratio between the target average power consumption and the determined instantaneous power consumption; adjusting the ratio to account for electrical losses in a circuit comprising the power supply and the heating element; and applying the adjusted ratio to the time period to determine the ON proportion of the time period.

[0120] In this way, losses in the power delivered by the power supply may be accounted for such that the target average power consumption may be reliably and accurately achieved.

[0121] As an illustrative example, that is not intended to be limiting in the context of the present disclosure, if the adjusted ratio was indicative that the instantaneous power consumption of the heating element was double the target average power consumption, then the ON proportion of the time period would be determined to be half the total length of the time period. In other words, the ON proportion of the time period is determined in a manner that is inversely proportional to the ratio of the target average power consumption to the instantaneous power consumption.

[0122] In another aspect, there is provided a heat-not-burn, HNB, aerosol-generating apparatus comprising: a heating element configured to heat an aerosol precursor; a power supply configured to supply electrical current to the heating element; a measurement resistor having a predetermined resistance; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out any of the methods described herein. The heating element is heatable by flowing electrical current therethrough.

[0123] In another aspect there may be provided a computer-readable medium, or a computer program comprising logic and / or instructions that, when executed by a processor of a HNB aerosol-generating apparatus, cause the HNB aerosol-generating apparatus to carry out the methods described herein.

[0124] In an aspect, there is provided a method of operating a heat-not-burn, HNB, aerosol-generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a power supply for supplying power to the heating element. The method comprises: monitoring a temperature of the heating element during operation of the HNB aerosol-generating apparatus. The monitoring comprises consecutively determining an instantaneous operational parameter value of the heating element to form a sequence of instantaneous operational parameter values of the heating element. The method further comprises determining a rolling average value of the operational parameter of the heating element based on the sequence of instantaneous operational parameter values; determining a difference between one instantaneous operational parameter value of the sequence of instantaneous operational parameter values and the determined rolling average value; and, if the determined difference exceeds a predetermined difference threshold, boosting a power output from a default power level to a relatively higher boosted power level of the power supply to supply the boosted power level to the heating element.

[0125] In some examples, the operational parameter may be a resistance of the heating element. In such examples, the rolling average value may be a rolling average value of the resistance of the heating element.

[0126] In other words, each instantaneous operational parameter value may be an instantaneous resistance value, and the rolling average value may be a rolling average value of the resistance of the heating element.

[0127] In other examples, each determined instantaneous operational parameter value may be a directly determined temperature value (e.g., using a temperature sensor), or may correspond to any operational parameter from which the temperature of the heating element may be inferred.

[0128] When a user of an HNB aerosol generating apparatus draws (i.e., inhales) on a mouthpiece of the apparatus, air is drawn across a surface of the heating element. This cools the heating element, causing its temperature and resistance to drop in response to the airflow across the surface of the heating element. Without intervention, the heating element may require anywhere from 10 to 20 seconds to recover back to its normal (or default) operational resistance and temperature. Therefore, boosting the power to more quickly recover the steady state operational temperature of the (resistive) heating element may advantageously facilitate a more consistent user experience for a user of the HNB aerosol-generating apparatus by ensuring that the steady-state / normal / default operation of the apparatus is resumed more quickly after drawing on the apparatus to inhale generated aerosol.

[0129] In some embodiments, boosting the power output may comprise boosting the power output for a predetermined boost period.

[0130] In some examples, the predetermined boost period may be 10 seconds or less, 5 seconds or less, 3 seconds or less, 1 second or less, or 0.5 seconds or less. In some examples, the predetermined boost period may be 0.5 seconds or more, 1 second or more, 3 seconds or more, 5 seconds or more, or 10 seconds or more. In some examples the predetermined boost period may be between 0.5 and 10 seconds, between 0.5 and 5 seconds, between 0.5 and 3 seconds, between 0.5 and 1 second, between 1 and 10 seconds, between 1 and 5 seconds, between 1 and 3 seconds, between 3 and 10 seconds, between 3 and 5 seconds, or between 5 and 10 seconds.

[0131] In a particular example, the predetermined boost period may be between 1 and 3 seconds.

[0132] In some examples, the predetermined difference threshold may be a difference between determined instantaneous resistance and the corresponding determined rolling average of 500 mΩ or less, 250 mΩ or less, 100 mΩ or less, 50 mΩ or less, 25 mΩ or less, or 10 mΩ or less. In some examples, the predetermined difference threshold may be a difference between determined instantaneous resistance and the corresponding determined rolling average of 10 mΩ or more, 25 mΩ or more, 50 mΩ or more, 100 mΩ or more, 250 mΩ or more, or 500 mΩ or more. In some examples, the predetermined difference threshold may be a difference between the determined instantaneous resistance and the determined rolling average of between 10 and 500 mΩ, between 10 and 250 mΩ, between 10 and 100 mΩ, between 10 and 50 mΩ, between 10 and 25 mΩ, between 25 and 500 mΩ, between 25 and 250 mΩ, between 25 and 100 mΩ, between 25 and 50 mΩ, between 50 and 500 mΩ, between 50 and 250 mΩ, between 50 and 100 mΩ, between 100 and 500 mΩ, between 100 and 250 mΩ, or between 250 and 500 mΩ.

[0133] In a particular example, the predetermined difference threshold may be a difference between determined instantaneous resistance and the corresponding determined rolling average of 50 mΩ.

[0134] In some embodiments, the difference threshold may be one of a plurality of difference thresholds and the boosted power level may be one of a plurality of boosted power levels. Each of the boosted power levels may correspond to one of the difference thresholds. Boosting the power output of the power supply may comprise: determining a highest of the plurality of difference thresholds that the determined difference exceeds; and boosting the power output of the power supply to supply the boosted power level corresponding to the determined highest of the plurality of difference thresholds.

[0135] In other words, the method may comprise boosting the power output of the power supply to a level that is proportional to the magnitude of the determined difference between one of the determined instantaneous resistance values and the determined rolling average value.

[0136] In this way, a variable (or graduated) level of control may be facilitated that allows a user to ensure that drops in the resistance / temperature of the heating element may be more efficiently mitigated (e.g., by more quickly returning the power consumption of the resistor to a normal, or standard, operating level).

[0137] In some embodiments, each of the plurality of boosted power levels may be proportional to the magnitude of the corresponding difference threshold.

[0138] In other words, the method may comprise boosting the power output of the power supply to a level that is proportional to the magnitude of the determined difference between one of the determined instantaneous resistance values and the determined rolling average value.

[0139] In this way, a variable (or graduated) level of control may be facilitated that allows a user to ensure that drops in the resistance / temperature of the heating element may be more efficiently mitigated (e.g., by more quickly returning the power consumption of the heating element to a normal, or standard, operating level).

[0140] In some embodiments, the consecutive determining of the instantaneous operational parameter values to form the sequence of instantaneous operational parameter values may be carried out at a predetermined interval.

[0141] In other words, a determination of a successive instantaneous operational parameter values may be carried out at the end of each predetermined interval - i.e., a time of length equal to the predetermined interval may pass between each consecutive determination of successive instantaneous operational parameter values.

[0142] In some examples, the predetermined interval may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the predetermined interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the predetermined interval may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0143] In a particular example, the predetermined interval may be 20 ms.

[0144] In some embodiments, the determining the difference between one of the determined instantaneous operational parameter values and the determined rolling average value may comprise determining the difference between the most recently determined instantaneous operational parameter value and the rolling average value.

[0145] In other words, the difference between an instantaneous operational parameter value of the heating element and the determined rolling average may be monitored and updated with each consecutive determination of the successive instantaneous operational parameter value.

[0146] In some embodiments, determining the rolling average value of the operational parameter values of the heating element may comprise determining an average of a portion of the sequence of instantaneous operational parameter values. Said plurality may comprise a predetermined number of determined instantaneous operational parameter values.

[0147] In some embodiments, the portion of the sequence of instantaneous operational parameter values may be defined by the most recent predetermined number of determined instantaneous operational parameter values.

[0148] In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be 500 or less, 250 or less, 100 or less, 50 or less, or 25 or less. In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be 25 or more, 50 or more, 100 or more, 250 or more, or 500 or more. In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be between 25 and 500, between 25 and 250, between 25 and 100, between 25 and 50, between 50 and 500, between 50 and 250, between 50 and 100, between 100 and 500, or between 100 and 250.

[0149] In a particular example, the most recent predetermined number of determined instantaneous operational parameter values may be between 50 and 100.

[0150] In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be a number of operational parameter values determined over a predetermined rolling average time period. In other words, the predetermined rolling average time period may be a time period over which the rolling average is determined. In some examples, the predetermined rolling average time period may be 5 seconds or less, 2 seconds or less, 1 second or less, or 0.5 seconds or less. Alternatively, in some examples, the predetermined rolling average time period may be 0.5 seconds or more, 1 second or more, 2 seconds or more, or 5 seconds or more. Alternatively, in some examples, the predetermined rolling average time period may be between 0.5 and 5 seconds, between 0.5 and 2 seconds, between 0.5 and 1 seconds, between 1 and 5 seconds, between 1 and 2 seconds, or between 2 and 5 seconds.

[0151] In a particular example, the predetermined rolling average time period may be between 1 and 2 seconds.

[0152] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element to define a potential divider. Determining each of the plurality of instantaneous resistance values may comprise: applying a supply voltage, by the power supply, across the measurement resistor and the heating element for a measurement period; measuring a midpoint voltage between the measurement resistor and the heating element; and determining an instantaneous resistance of the heating element based on the measured midpoint voltage.

[0153] In some embodiments, determining the instantaneous resistance may comprise comparing the midpoint voltage to the supply voltage to determine the instantaneous resistance.

[0154] In some embodiments, determining the instantaneous resistance may comprise equating the ratio of the instantaneous resistance to a combined resistance with the ratio of the midpoint voltage to the supply voltage. The combined resistance may be a sum of the predetermined resistance of the measurement resistor and the instantaneous resistance of the heating element.

[0155] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element. Determining each of the plurality of instantaneous resistance values may comprise: supplying, by the power supply, a current through the measurement resistor and the heating element; measuring the current passing through the measurement resistor; and determining an instantaneous resistance of the heating element based on the measured current.

[0156] In some embodiments, determining the instantaneous resistance may comprise determining an instantaneous power consumption of the heating element based on a supply voltage of the power supply and the measured current, and determining the instantaneous resistance based on the instantaneous power consumption.

[0157] In some embodiments, the predetermined resistance of the measurement resistor may be less than a nominal resistance of the heating element.

[0158] In other words, determining the instantaneous resistance may comprise applying any of the methods described herein in relation to any other aspects of the present disclosure. For example, any of the methods described herein in relation to operating a measurement resistor in a potential-divider configuration, and / or operating a resistor in a configuration for measuring current passing therethrough may be applied to determine the instantaneous resistance.

[0159] In an aspect, there is provided a method of operating a heat-not-burn, HNB, aerosol-generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a power supply for supplying power to the heating element. The method comprises: monitoring a resistance of the heating element during operation of the HNB aerosol-generating apparatus; determining a rate of change of the resistance of the heating element over time based on the monitoring of the resistance of the heating element; comparing the determined rate of change to a threshold; and determining a property of a consumable of the aerosol-generating apparatus based on whether or note the determined rate of change exceeds the threshold.

[0160] In some examples, the threshold may be a final threshold. If the determined rate of change exceeds the final threshold, the method further comprises: determining that a consumable is not installed in the aerosol-generating apparatus; and if the determined rate of change does not exceed the final threshold, determining that a consumable is installed in the aerosol-generating apparatus.

[0161] In this way, it may be possible to infer the presence of absence of a consumable in a HNB aerosol-generating apparatus by using pre-existing circuitry (e.g., implemented for use with any of the other methods described herein).

[0162] In some examples, the determined rate of change may be monitored (e.g., continuously monitored) and the comparison of the determined rate of change with the final threshold may be repeated (or iterated) at a predetermined comparison interval.

[0163] In some examples, the comparison interval may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the comparison interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the comparison interval may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0164] In a particular example, the comparison interval may be 20 ms.

[0165] In some embodiments, monitoring the resistance of the heating element may comprise consecutively determining an instantaneous resistance value of the heating element to form a sequence of instantaneous resistance values.

[0166] In some embodiments, each of the sequence of instantaneous resistance values may be determined at a predetermined interval.

[0167] In other words, a determination of a successive instantaneous resistance values may be carried out at the end of each predetermined interval - i.e., a time of length equal to the predetermined interval may pass between each consecutive determination of successive instantaneous resistances.

[0168] In some examples, the predetermined interval may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the predetermined interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the predetermined interval may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0169] In a particular example, the predetermined interval may be 20 ms.

[0170] In some examples, the predetermined interval and the comparison interval may be the same.

[0171] In some examples, that comparison interval maybe a multiple of the predetermined interval.

[0172] In some embodiments, determining the rate of change of the resistance of the heating element may comprise determining a gradient in the sequence of instantaneous resistance values over time.

[0173] Determining the gradient may, for example, involve determining a numerical differentiation of the sequence of instantaneous resistance values over time (i.e., dR / dt).

[0174] In some embodiments, the method may further comprise, in response to determining that a consumable is not installed in the aerosol-generating apparatus, deactivating the aerosol-generating apparatus.

[0175] When implemented with other methods of those described herein, a power level delivered to the heating element may be boosted upon initialisation of the aerosol-generating apparatus so as to ensure the temperature of the consumable reaches an aerosolization temperature (i.e., a temperature sufficient to generate aerosol) more quickly than is achievable by applying a constant power level. However, if there is no consumable installed in the aerosol-generating apparatus, delivering high power to the heating element risks damaging components of the aerosol generating apparatus and may present a safety risk to users of the apparatus.

[0176] As such, by deactivating the aerosol-generating apparatus, a fail-safe is provided that reduces (or event eliminates) both the damage risk and the safety risk.

[0177] In some embodiments, the threshold may be one of a plurality of thresholds that comprise one or more intermediate thresholds. The method may further comprise: comparing the determined rate of change to each of the one or more intermediate thresholds. For each of the one or more intermediate thresholds, if the determined rate of change of the resistance of the heating element exceeds said threshold, the method may further comprise determining that the mass of the consumable installed in the aerosol-generating apparatus is no more than a corresponding threshold mass. For each of the one or more intermediate thresholds, if the determined rate of change of the resistance of the heating element does not exceed said threshold, the method may further comprise determining that the mass of the consumable installed in the aerosol-generating apparatus is more than the corresponding threshold mass.

[0178] In this way, it may be possible to infer the mass of the consumable installed in the aerosol-generating apparatus by using pre-existing circuity (e.g., implemented for use with any of the other methods described herein).

[0179] In some examples, the comparison of the determined rate of change with each of one or more intermediate thresholds may be repeated (or iterated) at a predetermined intermediate comparison interval.

[0180] In some examples, the intermediate comparison interval maybe 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the intermediate comparison interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the comparison intermediate comparison interval maybe between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0181] In a particular example, the intermediate comparison interval may be 20 ms.

[0182] In some examples, the comparison interval and the intermediate comparison interval may be the same.

[0183] In some examples the Intermediate comparison interval and the predetermined interval may be the same.

[0184] In some examples, all of the intermediate comparison interval, the comparison interval, and the predetermined interval may be the same.

[0185] In some examples, the intermediate comparison interval may be a multiple of the comparison interval.

[0186] In some examples, the intermediate comparison interval may be a multiple of the predetermined interval.

[0187] In some embodiments, the method may further comprise: selecting a power level from amongst one or more predetermined power levels, each corresponding to one of the one or more intermediate thresholds. The selected power level may be selected as the power level corresponding to the lowest intermediate threshold exceeded by the determined rate of change of resistance. The method may further comprise adjusting a power input delivered to the heating element to the selected power level.

[0188] In this way, a power level delivered to heating element may be adjusted in accordance with

[0189] In some embodiments, the power of each of the one or more predetermined power levels is inversely proportional to the corresponding one or more intermediate thresholds.

[0190] Power required to deliver a consistent user experience to a user of the aerosol generating operators may be inversely proportional to a mass of the consumable or stick used to generate aerosol. Therefore, by delivering a power that is inversely proportional to the corresponding intermediate threshold of the one or more intermediate thresholds a more consistent user experience may be ensured for the user of the aerosol generating apparatus.

[0191] In some embodiments, at least one of the one or more intermediate thresholds may be a refill threshold. The method may further comprise: in response to determining that the determined rate of change of the resistance of the heating element exceeds the refill threshold, alerting a user of the aerosol-generating apparatus that the mass of the consumable installed in the aerosol-generating apparatus has fallen below a mass-refill threshold.

[0192] The mass-refill threshold may be a threshold indicative that a refill is needed now or in the near future to ensure that the user can continue to use their aerosol generating apparatus.

[0193] In some examples, alerting the user of the aerosol generating apparatus may involve using any suitable mechanism via any suitable component of the aerosol generating apparatus. For example alerting the user may involve presenting the user with a visual indicator (e.g., a light or LED, such as an orange light or LED that may or may not be flashing). Additionally or alternatively, alerting the user may involve presenting the user with an audible indicator (e.g., an alarm, ping, buzz or any other suitable sound via a speaker of the aerosol-generating apparatus). Personally or alternatively, alerting the user may involve presenting the user with a haptic indicator (e.g., a vibration of the aerosol-generating apparatus, or at least a part of the aerosol-generating apparatus).

[0194] In some embodiments, the method may further comprise, in response to determining that a consumable is not installed in the aerosol-generating apparatus, alerting a user of the aerosol-generating apparatus that a consumable is not installed in the aerosol-generating apparatus.

[0195] In some examples, alerting the user of the aerosol generating apparatus may involve using any suitable mechanism via any suitable component of the aerosol generating apparatus. For example alerting the user may involve presenting the user with a visual indicator (e.g., a light or LED, such as an red light or LED that may or may not be flashing). Additionally or alternatively, alerting the user may involve presenting the user with an audible indicator (e.g., an alarm, ping, buzz or any other suitable sound via a speaker of the aerosol-generating apparatus). Personally or alternatively, alerting the user may involve presenting the user with a haptic indicator (e.g., a vibration of the aerosol-generating apparatus, or at least a part of the aerosol-generating apparatus).

[0196] In some embodiments, the method may further comprise, in response to determining that a consumable is installed in the aerosol-generating apparatus, presenting a user of the aerosol-generating apparatus with an indication that the aerosol-generating apparatus is ready for use.

[0197] In some examples the indication maybe a visual indicator (e.g., a light or a LED such as a green light or a LED that may or may not be flashing). Additionally or alternatively the indication maybe an audible indicator (e.g., an alarm, ping, buzz or any other suitable sound via a speaker of the aerosol generating apparatus). Additionally or alternatively. The indication maybe a haptic indicator (e.g. a vibration of the aerosol generating apparatus or at least a part of the aerosol generating apparatus).

[0198] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element to define a potential divider. Determining each of the sequence of instantaneous resistance values may comprise: applying a supply voltage, by the power supply, across the measurement resistor and the heating element for a measurement period; measuring a midpoint voltage between the measurement resistor and the heating element; and determining an instantaneous resistance of the heating element based on the measured midpoint voltage.

[0199] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element. Determining each of the sequence of instantaneous resistance values may comprise: supplying, by the power supply, a current through the measurement resistor and the heating element; measuring the current passing through the measurement resistor; and determining an instantaneous resistance of the heating element based on the measured current.

[0200] In other words, determining the instantaneous resistance may comprise applying any of the methods described herein in relation to any other aspects of the present disclosure. For example, any of the methods described herein in relation to operating a measurement resistor in a potential-divider configuration, and / or operating a resistor in a configuration for measuring current passing therethrough may be applied to determine the instantaneous resistances.

[0201] In some examples, of any of the aspects described herein, when a user activates a HNB aerosol-generating apparatus, the heating element of the aerosol-generating apparatus may be activated for a predetermined period of time, referred to as a "session length". For example, the session length may be eight minutes or less, six minutes or less, four minutes or less, two minutes or less, or one minute or less. Alternatively, the session length may be one minute or more, two minutes or more, four minutes or more, six minutes or more, or eight minutes or more. Alternatively, the session length may be between one and eight minutes, one and six minutes, one and four minutes, one and two minutes, two and eight minutes, two and six minutes, two and four minutes, four and eight minutes, four and six minutes, or six and eight minutes.

[0202] In embodiments and examples where the mass of the consumable is determined (or at least it is determined whether the mass is greater or less than each of a set of mass thresholds), the methods described herein may further comprise: adjusting a session length of the HNB aerosol-generating apparatus based on the determined mass.

[0203] For example, the session length may be inversely proportional to the determined mass of the consumable. In other words, as the mass of the consumable is depleted, the session length delivered upon activation of the heating element may be reduced to reduce the risk of the consumable being completely depleted during a session. Additionally, application of heat, by the heating element, to a relatively lower-mass consumable may result in the consumable being heated to a target temperature (e.g., a steady-state temperature, and / or a temperature at which aerosol is generated from the consumable) relatively more quickly. As such, the session length needed to deliver the same amount of aerosol to a user of the HNB aerosol-generating apparatus may be shorter than for a relatively higher-mass consumable.

[0204] Additionally or alternatively, in embodiments and examples where a power-boost control is applied to the HNB aerosol-generating apparatus (e.g., in cases where the method of operating the HNB aerosol-generating apparatus includes boosting the power output of a power supply to the heating element of the aerosol-generating apparatus in response to a determination that a difference between an instantaneous resistance of the heating element and a rolling average of the resistance of the heating element exceeds a predetermined threshold), the methods described herein may further comprise: adjusting a session length of the HNB aerosol-generating apparatus based on a determined power output supplied to the heating element over the course of a session.

[0205] For example, in sessions during which a larger number of power boosts have been delivered to the heating element, the session length may be adjusted such that a total power delivered to the heating element over the course of the session does not exceed a predetermined total power threshold. In this way, the amount of aerosol generated across different sessions can be made more consistent by ensuring that the amount of power delivered to the heating element within each session (and, consequently, the amount of aerosol generated in each session) remains constant or approximately constant.

[0206] As an example, the session length may be adjusted such that each session comprises an amount of time at which the heating element is operating at a steady-state temperature (and / or a temperature at which aerosol is generated from the consumable) is the same, or approximately the same, across different sessions.

[0207] In another aspect, there is provided a heat-not-burn, HNB, aerosol-generating apparatus comprising: a heating element configured to heat an aerosol precursor; a power supply configured to supply electrical current to the heating element; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out any of the methods described herein. The heating element is heatable by flowing electrical current therethrough.

[0208] In another aspect there may be provided a computer-readable medium, or a computer program comprising logic and / or instructions that, when executed by a processor of a HNB aerosol-generating apparatus, cause the HNB aerosol-generating apparatus to carry out the methods described herein.

[0209] The present disclosure may provide electrical circuitry and / or a computer program configured to cause an aerosol generating apparatus / system to perform any method or method step disclosed herein. A computer readable medium comprising the computer program is also disclosed.

[0210] The preceding summary is provided for purposes of summarizing some examples to provide a basic understanding of aspects of the subject matter described herein. Accordingly, the above-described features should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Moreover, the above and / or proceeding examples may be combined in any suitable combination to provide further examples, except where such a combination is clearly impermissible or expressly avoided. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following text and the accompanying drawings.BRIEF DESCRIPTION OF THE FIGURES

[0211] Aspects, features and advantages of the present disclosure will become apparent from the following description of examples in reference to the appended drawings in which like numerals denote like elements. Fig. 1 is a block system diagram showing an example aerosol generating apparatus. Fig. 2 is a block system diagram showing an example implementation of the apparatus of Fig. 1, where the aerosol generating apparatus is configured to generate aerosol from a solid precursor. Fig. 3 is a schematic diagram showing an example implementation of the apparatus of Fig. 4. Fig. 4 shows an exemplary circuit for carrying out the methods described herein. Fig. 5 shows a method of operating an aerosol-generating apparatus. Fig. 6 shows an exemplary circuit for carrying out the methods described herein. Fig. 7 shows a method of operating an aerosol-generating apparatus. Fig. 8 shows a method of operating an aerosol-generating apparatus. Fig. 9 shows a method of operating an aerosol-generating apparatus. Fig. 10 shows a method of operating an aerosol-generating apparatus. DETAILED DESCRIPTION OF EMBODIMENTS

[0212] Before describing several examples implementing the present disclosure, it is to be understood that the present disclosure is not limited by specific construction details or process steps set forth in the following description and accompanying drawings. Rather, it will be apparent to those skilled in the art having the benefit of the present disclosure that the systems, apparatuses and / or methods described herein could be embodied differently and / or be practiced or carried out in various alternative ways.

[0213] Unless otherwise defined herein, scientific and technical terms used in connection with the presently disclosed inventive concept(s) shall have the meanings that are commonly understood by those of ordinary skill in the art, and known techniques and procedures may be performed according to conventional methods well known in the art and as described in various general and more specific references that may be cited and discussed in the present specification.

[0214] Any patents, published patent applications, and non-patent publications mentioned in the specification are hereby incorporated by reference in their entirety.

[0215] All examples implementing the present disclosure can be made and executed without undue experimentation in light of the present disclosure. While particular examples have been described, it will be apparent to those of skill in the art that variations may be applied to the systems, apparatus, and / or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit, and scope of the inventive concept(s). All such similar substitutions and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the inventive concept(s) as defined by the appended claims.

[0216] The use of the term "a" or "an" in the claims and / or the specification may mean "one," as well as "one or more," "at least one," and "one or more than one." As such, the terms "a," "an," and "the," as well as all singular terms, include plural referents unless the context clearly indicates otherwise. Likewise, plural terms shall include the singular unless otherwise required by context.

[0217] The use of the term "or" in the present disclosure (including the claims) is used to mean an inclusive "and / or" unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive. For example, a condition "A or B" is satisfied by any of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0218] As used in this specification and claim(s), the words "comprising, "having," "including," or "containing" (and any forms thereof, such as "comprise" and "comprises," "have" and "has," "includes" and "include," or "contains" and "contain," respectively) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0219] Unless otherwise explicitly stated as incompatible, or the physics or otherwise of the embodiments, examples, or claims prevent such a combination, the features of examples disclosed herein, and of the claims, may be integrated together in any suitable arrangement, especially ones where there is a beneficial effect in doing so. This is not limited to only any specified benefit, and instead may arise from an "ex post facto" benefit. This is to say that the combination of features is not limited by the described forms, particularly the form (e.g. numbering) of example(s), embodiment(s), or dependency of claim(s). Moreover, this also applies to the phrase "in one embodiment," "according to an embodiment," and the like, which are merely a stylistic form of wording and are not to be construed as limiting the following features to a separate embodiment to all other instances of the same or similar wording. This is to say, a reference to 'an,' 'one,' or 'some' embodiment(s) may be a reference to any one or more, and / or all embodiments, or combination(s) thereof, disclosed. Also, similarly, the reference to "the" embodiment may not be limited to the immediately preceding embodiment. Further, all references to one or more embodiments or examples are to be construed as non-limiting to the claims.

[0220] The present disclosure may be better understood in view of the following explanations, wherein the terms used that are separated by "or" may be used interchangeably: As used herein, an "aerosol generating apparatus" (or "electronic(e)-cigarette") may be an apparatus configured to deliver an aerosol to a user for inhalation by the user. The apparatus may additionally / alternatively be referred to as a "smoking substitute apparatus", if it is intended to be used instead of a conventional combustible smoking article. As used herein a combustible "smoking article" may refer to a cigarette, cigar, pipe or other article, that produces smoke (an aerosol comprising solid particulates and gas) via heating above the thermal decomposition temperature (typically by combustion and / or pyrolysis). An aerosol generated by the apparatus may comprise an aerosol with particle sizes of 0.2 - 7 microns, or less than 10 microns, or less than 7 microns. This particle size may be achieved by control of one or more of: heater temperature; cooling rate as the vapour condenses to an aerosol; flow properties including turbulence and velocity. The generation of aerosol by the aerosol generating apparatus may be controlled by an input device. The input device may be configured to be user-activated, and may for example include or take the form of an actuator (e.g. actuation button) and / or an airflow sensor.

[0221] Each occurrence of the aerosol generating apparatus being caused to generate aerosol for a period of time (which may be variable) may be referred to as an "activation" of the aerosol generating apparatus. The aerosol generating apparatus may be arranged to allow an amount of aerosol delivered to a user to be varied per activation (as opposed to delivering a fixed dose of aerosol), e.g. by activating an aerosol generating unit of the apparatus for a variable amount of time, e.g. based on the strength / duration of a draw of a user through a flow path of the apparatus (to replicate an effect of smoking a conventional combustible smoking article).

[0222] The aerosol generating apparatus may be portable. As used herein, the term "portable" may refer to the apparatus being for use when held by a user.

[0223] As used herein, an "aerosol generating system" may be a system that includes an aerosol generating apparatus and optionally other circuitry / components associated with the function of the apparatus, e.g., one or more external devices and / or one or more external components (here "external" is intended to mean external to the aerosol generating apparatus). As used herein, an "external device" and "external component" may include one or more of a: a charging device, a mobile device (which may be connected to the aerosol generating apparatus, e.g. via a wireless or wired connection); a networked-based computer (e.g. a remote server); a cloud-based computer; any other server system.

[0224] An example aerosol generating system may be a system for managing an aerosol generating apparatus. Such a system may include, for example, a mobile device, a network server, as well as the aerosol generating apparatus.

[0225] As used herein, an "aerosol" may include a suspension of precursor, including as one or more of: solid particles; liquid droplets; gas. Said suspension may be in a gas including air. An aerosol herein may generally refer to / include a vapour. An aerosol may include one or more components of the precursor.

[0226] As used herein, a "precursor" may include one or more of a: liquid; solid; gel; loose leaf material; other substance. The precursor may be processed by an aerosol generating unit of an aerosol generating apparatus to generate an aerosol. The precursor may include one or more of: an active component; a carrier; a flavouring. The active component may include one or more of nicotine; caffeine; a cannabidiol oil; a non-pharmaceutical formulation, e.g. a formulation which is not for treatment of a disease or physiological malfunction of the human body. The active component may be carried by the carrier, which may be a liquid, including propylene glycol and / or glycerine. The term "flavouring" may refer to a component that provides a taste and / or a smell to the user. The flavouring may include one or more of: Ethylvanillin (vanilla); menthol, Isoamyl acetate (banana oil); or other. The precursor may include a substrate, e.g. reconstituted tobacco to carry one or more of the active component; a carrier; a flavouring.

[0227] As used herein, a "storage portion" may be a portion of the apparatus adapted to store the precursor. It may be implemented as fluid-holding reservoir or carrier for solid material depending on the implementation of the precursor as defined above.

[0228] As used herein, a "flow path" may refer to a path or enclosed passageway through an aerosol generating apparatus, e.g. for delivery of an aerosol to a user. The flow path may be arranged to receive aerosol from an aerosol generating unit. When referring to the flow path, upstream and downstream may be defined in respect of a direction of flow in the flow path, e.g. with an outlet being downstream of an inlet.

[0229] As used herein, a "delivery system" may be a system operative to deliver an aerosol to a user. The delivery system may include a mouthpiece and a flow path.

[0230] As used herein, a "flow" may refer to a flow in a flow path. A flow may include aerosol generated from the precursor. The flow may include air, which may be induced into the flow path via a puff by a user.

[0231] As used herein, a "puff" (or "inhale" or "draw") by a user may refer to expansion of lungs and / or oral cavity of a user to create a pressure reduction that induces flow through the flow path.

[0232] As used herein, an "aerosol generating unit" may refer to a device configured to generate an aerosol from a precursor. The aerosol generating unit may include a unit to generate a vapour directly from the precursor (e.g. a heating system or other system) or an aerosol directly from the precursor (e.g. an atomiser including an ultrasonic system, a flow expansion system operative to carry droplets of the precursor in the flow without using electrical energy or other system). A plurality of aerosol generating units to generate a plurality of aerosols (for example, from a plurality of different aerosol precursors) may be present in an aerosol generating apparatus.

[0233] As used herein, a "heating system" may refer to an arrangement of at least one heating element, which is operable to aerosolise a precursor once heated. The at least one heating element may be electrically resistive to produce heat from the flow of electrical current therethrough. The at least one heating element may be arranged as a susceptor to produce heat when penetrated by an alternating magnetic field. The heating system may be configured to heat a precursor to below 300 or 350 degrees C, including without combustion.

[0234] As used herein, a "consumable" may refer to a unit that includes a precursor. The consumable may include an aerosol generating unit, e.g. it may be arranged as a cartomizer. The consumable may include a mouthpiece. The consumable may include an information carrying medium. With liquid or gel implementations of the precursor, e.g. an e-liquid, the consumable may be referred to as a "capsule" or a "pod" or an "e-liquid consumable". The capsule / pod may include a storage portion, e.g. a reservoir or tank, for storage of the precursor. With solid material implementations of the precursor, e.g. tobacco or reconstituted tobacco formulation, the consumable may be referred to as a "stick" or "package" or "heat-not-burn consumable". In a heat-not-burn consumable, the mouthpiece may be implemented as a filter and the consumable may be arranged to carry the precursor. The consumable may be implemented as a dosage or pre-portioned amount of material, including a loose-leaf product.

[0235] As used herein, an "information carrying medium" may include one or more arrangements for storage of information on any suitable medium. Examples include: a computer readable medium; a Radio Frequency Identification (RFID) transponder; codes encoding information, such as optical (e.g. a bar code or QR code) or mechanically read codes (e.g. a configuration of the absence or presents of cut-outs to encode a bit, through which pins or a reader may be inserted).

[0236] As used herein "heat-not-burn" (or "HNB" or "heated precursor") may refer to the heating of a precursor, typically tobacco, without combustion, or without substantial combustion (i.e. localised combustion may be experienced of limited portions of the precursor, including of less than 5% of the total volume).

[0237] As used herein, "electrical circuitry" may refer to one or more electrical components, examples of which may include: an Application Specific Integrated Circuit (ASIC); electronic / electrical componentry (which may include combinations of transistors, resistors, capacitors, inductors etc); one or more processors; a non-transitory memory (e.g. implemented by one or more memory devices), that may store one or more software or firmware programs; a combinational logic circuit; interconnection of the aforesaid. The electrical circuitry may be located entirely at the apparatus, or distributed between the apparatus and / or on one or more external devices in communication with the apparatus, e.g. as part of a system

[0238] As used herein, a "processing resource" (or "processor" or "controller") may refer to one or more units for processing data, examples of which may include an ASIC, microcontroller, FPGA, microprocessor, digital signal processor (DSP) capability, state machine or other suitable component.

[0239] A processing resource may be configured to execute a computer program, e.g. which may take the form of machine readable instructions, which may be stored on a non-transitory memory and / or programmable logic. The processing resource may have various arrangements corresponding to those discussed for the circuitry, e.g. on-board and / or off board the apparatus as part of the system. As used herein, any machine executable instructions, or computer readable media, may be configured to cause a disclosed method to be carried out, e.g. by a aerosol generating apparatus or system as disclosed herein, and may therefore be used synonymously with the term method.

[0240] As used herein, an "external device" (or "peripheral device") may include one or more electronic components external to an aerosol generating apparatus. Those components may be arranged at the same location as the aerosol generating apparatus or remote from the apparatus. An external device may comprise electronic computer devices including: a smartphone; a PDA; a video game controller; a tablet; a laptop; or other like device.

[0241] As used herein, a "computer readable medium / media" (or "memory" or "data storage") may include any medium capable of storing a computer program, and may take the form of any conventional non-transitory memory, for example one or more of: random access memory (RAM); a CD; a hard drive; a solid state drive; a memory card; a DVD. The memory may have various arrangements corresponding to those discussed for the circuitry / processor. The present disclosure includes a computer readable medium configured to cause an apparatus or system disclosed herein to perform a method as disclosed herein.

[0242] It will be appreciated that any of the disclosed methods (or corresponding apparatuses, programs, data carriers, etc.) may be carried out by either a host or client, depending on the specific implementation (i.e. the disclosed methods / apparatuses are a form of communication(s), and as such, may be carried out from either 'point of view', i.e. in corresponding to each other fashion). Furthermore, it will be understood that the terms "receiving" and "transmitting" encompass "inputting" and "outputting" and are not limited to an RF context of transmitting and receiving electromagnetic (e.g. radio) waves. Therefore, for example, a chip or other device or component for realizing embodiments could generate data for output to another chip, device or component, or have as an input data from another chip, device, or component, and such an output or input could be referred to as "transmit" and "receive" including gerund forms, that is, "transmitting" and "receiving," as well as such "transmitting" and "receiving" within an RF context.

[0243] Referring to Fig. 1, an example aerosol generating apparatus 1 includes a power supply 2, for supply of electrical energy. The apparatus 1 includes an aerosol generating unit 4 that is driven by the power supply 2. The power supply 2 may include an electric power supply in the form of a battery and / or an electrical connection to an external power supply. The apparatus 1 includes a precursor 6, which in use is aerosolised by the aerosol generating unit 4 to generate an aerosol. The apparatus 2 includes a delivery system 8 for delivery of the aerosol to a user.

[0244] Electrical circuitry (not shown in figure 1) may be implemented to control the interoperability of the power supply 4 and aerosol generating unit 6.

[0245] In variant examples, which are not illustrated, the power supply 2 may be omitted since, e.g. an aerosol generating unit implemented as an atomiser with flow expansion may not require a power supply.

[0246] Fig. 2 shows an implementation of the apparatus 1 of Fig. 1, where the aerosol generating apparatus 1 is configured to generate aerosol by a-heat not-burn process.

[0247] In this example, the apparatus 1 includes a device body 50 and a consumable 70.

[0248] In this example, the body 50 includes the power supply 4 and a heating system 52. The heating system 54 includes at least one heating element 54. The body may additionally include any one or more of electrical circuitry 56, a memory 58, a wireless interface 60, one or more other components 62.

[0249] The electrical circuitry 56 may include a processing resource for controlling one or more operations of the body 50, e.g. based on instructions stored in the memory 58.

[0250] The wireless interface 60 may be configured to communicate wirelessly with an external (e.g. mobile) device, e.g. via Bluetooth.

[0251] The other component(s) 62 may include an actuator, one or more user interface devices configured to convey information to a user and / or a charging port, for example (see e.g. Fig. 3).

[0252] The body 50 is configured to engage with the consumable 70 such that the at least one heating element 54 of the heating system 52 penetrates into the solid precursor 6 of the consumable. In use, a user may activate the aerosol generating apparatus 1 to cause the heating system 52 of the body 50 to cause the at least one heating element 54 to heat the solid precursor 6 of the consumable (without combusting it) by conductive heat transfer, to generate an aerosol which is inhaled by the user.

[0253] Fig. 3 shows an example implementation of the aerosol generating device 1 of Fig. 2.

[0254] As depicted in Fig. 3, the consumable 70 is implemented as a stick, which is engaged with the body 50 by inserting the stick into an aperture at a top end 53 of the body 50, which causes the at least one heating element 54 of the heating system 52 to penetrate into the solid precursor 6.

[0255] The consumable 70 includes the solid precursor 6 proximal to the body 50, and a filter distal to the body 50. The filter serves as the mouthpiece of the consumable 70 and thus the apparatus 1 as a whole. The solid precursor 6 may be a reconstituted tobacco formulation.

[0256] In this example, the at least one heating element 54 is a rod-shaped element with a circular transverse profile. Other heating element shapes are possible, e.g., the at least one heating element may be blade-shaped (with a rectangular transverse profile) or tube-shaped (e.g. with a hollow transverse profile).

[0257] In this example, the body 50 includes a cap 51. In use the cap 51 is engaged at a top end 53 of the body 50. Although not apparent from Fig. 3, the cap 51 is moveable relative to the body 50. In particular, the cap 51 is slidable and can slide along a longitudinal axis of the body 50.

[0258] The body 50 also includes an actuator 55 on an outer surface of the body 50. In this example, the actuator 55 has the form of a button.

[0259] The body 50 also includes a user interface device configured to convey information to a user. Here, the user interface device is implemented as a plurality of lights 57, which may e.g., be configured to illuminate when the apparatus 1 is activated and / or to indicate a charging state of the power supply 4. Other user interface devices are possible, e.g., to convey information haptically or audibly to a user.

[0260] The body may also include an airflow sensor which detects airflow in the aerosol generating apparatus 1 (e.g., caused by a user inhaling through the consumable 70). This may be used to count puffs, for example.

[0261] In this example, the consumable 70 includes a flow path which transmits aerosol generated by the at least one heating element 54 to the mouthpiece of the consumable.

[0262] In this example, the aerosol generating unit 4 is provided by the above-described heating system 52 and the delivery system 8 is provided by the above-described flow path and mouthpiece of the consumable 70.

[0263] Fig. 4 shows an exemplary circuit 100 for carrying out the methods described herein.

[0264] The circuit 100 comprises a power supply 102 configured to supply a voltage, V BAT , to the circuit 100. The power supply 102 may, for example, be a battery (e.g., a rechargeable battery) arranged and configured to supply power to electrical components of the aerosol-generating apparatus 1.

[0265] The circuit 100 further comprises first and second switches 104, 106 arranged and configured to switchably connect the power supply 102 to and disconnect the power supply 102 from first and second circuit paths respectively.

[0266] The first and / or second switches 104, 106 may be implemented using field-effect transistor (FET) switches. The first and / or second switches 104, 106 may be implemented as P-channel FET switches.

[0267] The first switch 104 is arranged and configured to switchably connect the first circuit path and the power source 102. The first circuit path comprises a measurement resistor 108 having a predetermined resistance. The measurement resistor 108 is arranged in the first circuit path to define a portion of a potential divider. The first circuit path further comprises a voltage-measurement device 110 for measuring the voltage drop across the resistor 108 when the resistor 108 is supplied voltage from the power source 102. The voltage drop may be measured as a difference between the voltage supply by the power source 102, and a remaining voltage after the measurement resistor 108 - in other words, the voltage-measurement device 110 may be configured to measure a midpoint voltage of the first circuit path relative to the voltage supplied by the power source 102. Alternatively, the voltage-measurement device 110 may be configured to measure the amount of voltage remaining after the voltage drop across the resistor 110 - in other words, the voltage-measurement device 110 may be configured to measure a midpoint voltage of the first circuit path relative to electrical ground 116.

[0268] The voltage-measurement device 110 may be implemented using any appropriate means for measuring the voltage drop across the resistor 108. For example, the voltage-measurement device 110 may be implemented as a voltmeter and / or an analog-to-digital converter and / or any other suitable device or apparatus for measuring the voltage drop across the resistor 108.

[0269] The second switch 106 is arranged and configured to switchably connect the second circuit path and the power source 102. The second circuit path bypasses the resistor 108. The power source 102 is connectable to a heating element 122 via the first and / or second circuit paths. The heating element 122 may be a resistive heating element, for example a heater configured to generate heat resisistively in response to current passing therethrough.

[0270] The resistor 108 and the heating element 112 may have similar nominal resistances, as described above. For example, the resistor 108 may have a resistance of 1.6 Ω. The heating element 112 may have a nominal resistance of 1.1 ± 0.1 Ω.

[0271] The circuit 100 may further comprise a third switch 114 arranged and configured to switchably connect the heating element 112 to and disconnect the heating element 112 from electrical ground 116. The third switch 114 may be a FET switch. The third switch 114 may be implemented as a N-channel FET switch. The third switch 114, in this way, may provide a failsafe mechanism to prevent the heating element 112 from failing to respond to a control signal so as to avoid the heating element 112 failing into an ON configuration.

[0272] Fig. 5 shows a method of operating an aerosol-generating apparatus 1 comprising the circuit 100 of Fig. 4.

[0273] The method comprises, by an operation 202, applying a voltage - by power source 102 - across the heating element 112. On initialisation, the first switch 104 may be open and the second switch 106 may be closed such that the measurement resistor 108 is bypassed and voltage is only applied across the heating element 112. Alternatively, on initialisation the first switch 104 may be closed and the second switch 106 may be open such that the measurement resistor 108 is connected in series with the power source 102 and the heating element 112.

[0274] The method further comprises, by an operation 204, waiting for a settling time to elapse to ensure that the voltage being applied across the heating element 112 has a voltage-under-load value (that is typically lower than an initial voltage applicable by the power source 102 in the absence of a resistive load).

[0275] The settling time may, for example, be between 2 and 7 ms. For example, the settling time may be 5 ms.

[0276] The method further comprises, by an operation 206, in response to determining that the settling time has elapsed, switchably connecting the power supply 102 to the heating element 112 through the measurement resistor 108. For example, the operation 206 may comprise closing the first switch 104 and opening the second switch 106 such that the voltage is applied across the first circuit path of the circuit 100. However, as the skilled person will appreciate, in examples where the measurement resistor 108 is already connected in series with the power source 102 and the heating element 112, no action (e.g., no opening or closing of either the first or second switches 104, 106).

[0277] The method further comprises, by an operation 208, applying the supply voltage, V BAT , across the measurement resistor 108 and the heating element 112.

[0278] The method further comprises, by an operation 210, measuring a midpoint voltage between the measurement resistor 108 and the heating element 112. The midpoint voltage may be measured by the voltage-measurement device 110. The midpoint voltage may be indicative of the voltage drop across the measurement resistor 108.

[0279] In this way, the measurement resistor 108 and heating element 112 may be considered to be arranged in the configuration of a potential divider. Measuring the midpoint voltage (i.e., the voltage drop across the resistor 108), therefore enables a determination of an instantaneous resistance of the heating element 112.

[0280] The method further comprises, by an operation 212, connecting the power supply 102 to the heating element 112, bypassing the measurement resistor 108. For example, in the example shown in Fig. 4, the operation 212 comprises opening the first switch 104 and closing the second switch 106 such that the voltage is applied across the second circuit path of the circuit 100.

[0281] The method further comprises, by an operation 214, determining an instantaneous power consumption of the heating element 112. Determining the instantaneous power consumption of the heating element 112 may involve applying Ohm's power law (in the form of P = V 2< / R) to determine the instantaneous power consumption based on the supply voltage applied by the power source 102 and the determined instantaneous resistance of the heating element 112.

[0282] The method further comprises, by an operation 216, selecting an operational mode of the HNB aerosol-generating apparatus 1. The operational mode may, for example, be selected by the user providing user input via the system 80 of Fig. 4. Additionally or alternatively, the HNB aerosol-generating apparatus 1 may comprise a processor configured to select an operational mode of the apparatus 1, for example, in response to detecting and / or identifying the insertion / installation of a particular consumable 70 comprising a particular precursor 6.

[0283] Operational modes of the HNB aerosol-generating apparatus 1 may, for example, be selected to cause the heating element 112 to heat to a particular temperature suitable for heating and aerosolising a particular precursor 6.

[0284] The method further comprises, by an operation 218, determining an ON proportion of a time period for which the heating element 112 needs to be activated to achieve a target average power consumption. The target average power consumption may be a target corresponding to the operational mode selected in operation 216. For example, if the instantaneous power consumption of the heating element 112 is double the target average power consumption, then the ON proportion of the predetermined time period may be determined to be half the time period.

[0285] The method further comprises, by an operation 220, determining whether the ON proportion of the time period has elapsed.

[0286] Once the ON proportion of the time period has elapsed, the method further comprises, by an operation 222, in response to the ON proportion elapsing, disconnecting the power supply 102 such that the supply voltage is no longer applied across the heating element 112.

[0287] Stopping the application of the supply voltage may involve switchably disconnecting the power source 102 from electrical ground 116 by, e.g., opening the third switch 114 and / or the second switch 106.

[0288] One or more of the operations (for example operations 206 to 222 inclusive) may be repeated on a cyclical basis for the duration of the operation of the HNB aerosol-generating apparatus. For example, the full time period over which the method may be carried out may be 20 ms.

[0289] This time period, and the associated method may be repeated on a cyclical basis for the full duration of a user session of the apparatus 1. A user session may be a continuous or substantially continuous period of time during which a user is using the apparatus 1 to draw on generated aerosol. A typical user session may, for example, last between 1 and 10 minutes, e.g., 5 minutes.

[0290] Fig. 6 shows an exemplary circuit 300 for carrying out the methods described herein.

[0291] The circuit 300 comprises a power supply 302 configured to supply a voltage, V BAT , (and a corresponding current) to the circuit 300. The power supply 302 may, for example, be a battery (e.g., a rechargeable battery) arranged and configured to supply power to electrical components of the aerosol-generating apparatus 1.

[0292] The circuit 300 further comprises a first switch 304 arranged and configured to switchably connect the power supply 102 to and disconnect the power supply 102 from the rest of the circuit 300.

[0293] The first switch 304 may be implemented using a FET switch. The first switch 304 may be implemented as a P-channel FET switch.

[0294] The circuit 300 further comprises a measurement resistor 306 having a predetermined resistance. The measurement resistor 306 is arranged with a resistance much lower than a nominal resistance of a heating element 312 of the apparatus 1 (as described above), such that approximately or substantially all of the voltage supplied by the power source 102 is dropped across the heating element 312 and not the measurement resistor 306.

[0295] The circuit 300 further comprises one or more current-measurement devices 308, 310 arranged and configured to measure a current flowing through the measurement resistor 306. The one or more current-measurement device 308 may comprise a current-sense amplifier 308 and a voltage-measurement device 310 configured to measure a voltage output of the current-sense amplifier to infer the value of the current flowing through the measurement resistor 306. The voltage-measurement device 310 may be implemented using any appropriate means for measuring the voltage drop associated with the current-sense amplifier 310. For example, the voltage-measurement device 310 may be implemented as a voltmeter and / or an analog-to-digital converter and / or any other suitable device or apparatus for measuring the voltage drop associated with the current-sense amplifier 308.

[0296] Alternatively, the one or more current-measurement device 308, 310 may be any suitable device or apparatus (or combination thereof) for measuring the current flowing through the measurement resistor 306 (e.g., an ammeter).

[0297] The circuit 300 further comprises a heating element 312. The heating element may be a resistive heating element, for example a heater configured to generate heat resistively in response to current passing therethrough.

[0298] The circuit 300 may further comprise a second switch 314 arranged and configured to switchably connect the heating element 312 to and disconnect the heating element 312 from electrical ground 316. The second switch 314 may be a FET switch. The second switch 314 may be implemented as a N-channel FET switch.

[0299] Fig. 7 shows a method of operating an aerosol-generating apparatus 1 comprising the circuit 300 of Fig. 6.

[0300] The method comprises, by an operation 402, applying a current - by power source 302 -through the measurement resistor 306 and heating element 312. On initialisation, the first switch 304 and second switch 314 may both be closed to facilitate the flow of current through the circuit 300.

[0301] The method further comprises, by an operation 404, waiting for a settling time to elapse to ensure that the current being supplied through the circuit 300 has a current-under-load value (that is typically lower than an initial current applicable by the power source 302 in the absence of a resistive load).

[0302] The settling time may, for example, be between 2 and 7 ms. For example, the settling time may be 5 ms.

[0303] The method further comprises, by an operation 406, in response to determining that the settling time has elapsed, measuring the current flowing through the measurement resistor 306, for example using the current-sense amplifier 308 and voltage measuring device 310 shown in Fig. 7.

[0304] The method further comprises, by an operation 408, determining an instantaneous power consumption of the heating element 312. Determining the instantaneous power consumption of the heating element 312 may involve applying Ohm's power law (P = IV) to determine the instantaneous power consumption based on the supply voltage, V BAT , by the power source 302 and the determined current flowing through the resistor 306.

[0305] The method further comprises, by an operation 410, selecting an operational mode of the HNB aerosol-generating apparatus 1. The operational mode may, for example, be selected by the user providing user input via the system 80 of Fig. 4. Additionally or alternatively, the HNB aerosol-generating apparatus 1 may comprise a processor configured to select an operational mode of the apparatus 1, for example, in response to detecting and / or identifying the insertion / installation of a particular consumable 70 comprising a particular precursor 6.

[0306] Operational modes of the HNB aerosol-generating apparatus 1 may, for example, be selected to cause the heating element 112 to heat to a particular temperature suitable for heating and aerosolising a particular precursor 6.

[0307] The method further comprises, by an operation 412, determining an ON proportion of a time period for which the heating element 312 needs to be activated to achieve a target average power consumption. The target average power consumption may be a target corresponding to the operational mode selected in operation 410. For example, if the instantaneous power consumption of the heating element 312 is double the target average power consumption, then the ON proportion of the predetermined time period may be determined to be half the time period.

[0308] The method further comprises, by an operation 414, determining whether the ON proportion of the time period has elapsed.

[0309] Once the ON proportion of the time period has elapsed, the method further comprises, by an operation 416, in response to the ON proportion elapsing, disconnecting the power supply 302 such that the current is no longer applied through the heating element 312.

[0310] Stopping the application of the supply voltage may involve switchably disconnecting the power source 302 from electrical ground 316 by, e.g., opening the first switch 304 and / or the second switch 314.

[0311] One or more of the operations (for example operations 406 to 416 inclusive) may be repeated on a cyclical basis for the duration of the operation of the HNB aerosol-generating apparatus. For example, the full time period over which the method may be carried out may be 20 ms.

[0312] This time period, and the associated method may be repeated on a cyclical basis for the full duration of a user session of the apparatus 1. A user session may be a continuous or substantially continuous period of time during which a user is using the apparatus 1 to draw on generated aerosol. A typical user session may, for example, last between 1 and 10 minutes, e.g., 5 minutes.

[0313] Fig. 8 shows a method of operating an aerosol-generating apparatus 1 having power-boost functionality.

[0314] The method comprises, in an operation 502, monitoring the instantaneous resistance of the heating element 112, 312 by consecutively determining a plurality of instantaneous resistances of the heating element 112, 312 (e.g., at regular predetermined intervals). The determination of each of the instantaneous resistances may be carried out by implementing the same or similar methods set out above in relation to Figs. 5 and 7. For the avoidance of doubt, although Fig. 8 is described herein in relation to the determination of resistance values, the method is equally applicable in the context of monitoring a temperature of the heating element 112, 312 by consecutively determining a plurality of any instantaneous operational parameter values from which a temperature of the heating element 112, 312 may be inferred.

[0315] The method further comprises, in an operation 504, determining a rolling average of the resistance of the heating element 112, 312, for example by determining an average of a subset of the plurality of instantaneous resistances (e.g., the subset of instantaneous resistances determined in the most recent 1 to 2 seconds).

[0316] The method further comprises, in an operation 506, a difference between one of the determined instantaneous resistances (e.g., the most recently determined instantaneous resistance), and the determined rolling average of the resistance of the heating element 112, 312.

[0317] The method further comprises, in an operation 508, determining whether the determined difference exceeds a predetermined difference threshold. The predetermined difference threshold may be one of a plurality of different predetermined difference thresholds.

[0318] If the determined difference does not exceed the predetermined difference threshold, then the method may cyclically repeat by returning to operation 502 to determine the next of the consecutive instantaneous resistances.

[0319] If the determined difference does exceed the predetermined difference threshold, the method further comprises, in an operation 510, boosting a power output of the power supply 102, 302. This may induce a boosted power consumption by the heating element 112, 312 such that, when the heating element's 112, 312 power consumption drops below a threshold, the power supplied is boosted to return the heating element 112, 312 to standard (or normal) operating parameters more quickly.

[0320] In examples, where the predetermined difference threshold is one of a plurality of different predetermined difference thresholds, the power level to which the power supplied by the power source 102, 302 is boosted may be a preselected boosted power level that is inversely proportional to the magnitude of the corresponding difference threshold.

[0321] Boosting the power supply may involve boosting a power output of the power supply 102, 302 for an extended period of time (e.g., 1-3 seconds) to ensure that the power consumption of the heating element 112, 312 recovers to normal / standard operating levels.

[0322] Fig. 9 shows a method 600 of operating an aerosol-generating apparatus 1 to determine whether a consumable 70 is installed in the apparatus 1 or not.

[0323] The method 600 comprises, in an operation 602, monitoring the resistance of the heating element 112, 312 (e.g., by determining a plurality of instantaneous resistances of the heating element 112, 312 at regular predetermined intervals). The monitoring of the resistance may be carried out by implementing the same or similar methods set out above in relation to Figs. 5 and 7.

[0324] The method 600 further comprises, in an operation 604, determining a rate of change of the resistance of the heating element 112, 312 over time, for example by carrying out a numerical differentiation of the determined instantaneous resistances over time.

[0325] The method 600 further comprises, in an operation 606, comparing the determined rate of change to a final threshold. The final threshold may be individually calibrated for a specific aerosol-generating apparatus 1.

[0326] If the determined rate of change of the resistance of the heating element 112, 312 exceeds the final threshold, the method 600 proceeds to operation 608, in which it is determined that there is no consumable 70 installed in the aerosol-generating apparatus 1.

[0327] If it is determined that there is no consumable 70 installed in the aerosol-generating apparatus 1, the method 600 may further comprise, in an operation 610, alerting a user of the aerosol-generating apparatus 1 that there is no consumable 70 installed therein. The alert may, for example, take the form of an alarm (or other audible alert), a flashing red light (or other visible alert), or a vibration of the aerosol-generating apparatus 1 (or other haptic alert).

[0328] If it is determined that there is no consumable 70 installed in the aerosol-generating apparatus 1, the method 600 may further comprise, in an operation 612, deactivating the aerosol-generating apparatus, thereby reducing (or even eliminating) damage risks and safety risks of heating the heating element 112, 312 with no consumable 70 installed in the aerosol-generating apparatus 1.

[0329] If the determined rate of change of the resistance of the heating element 112, 312 does not exceed the final threshold, the method 600 proceeds to operation 614, in which it is determined that there is a consumable 70 installed in the aerosol-generating apparatus.

[0330] If it is determined that there is a consumable 70 installed in the aerosol-generating apparatus, the method 600 may further comprise, in an operation 616, providing the user with an indication that the consumable 70 is installed in the aerosol-generating apparatus 1. The indication may, for example, take the form of a green light (or other visible indication).

[0331] The method 600 may be repeated (or iterated) to provide a continuous or near-continuous monitoring of the rate of change of resistance of the heating element 112, 312 over time, and to provide a continuous or near-continuous monitoring of whether a consumable 70 is installed in the aerosol-generating apparatus 1 or not.

[0332] Alternatively, the method 600 may be carried out upon activation or initialisation of the aerosol-generating apparatus 1 - e.g., as part of a start-up sequence of the aerosol-generating apparatus 1.

[0333] Fig. 10 shows a method 700 of operating an aerosol-generating apparatus 1 to determine and / or monitor the mass of a consumable 70 installed in the apparatus 1. The method 700 of Fig. 10 may be carried out concurrently with or consecutively to the method 600 of Fig. 9.

[0334] The method 700 comprises, in an operation 702, monitoring the resistance of the heating element 112, 312 (e.g., by determining a plurality of instantaneous resistances of the heating element 112, 312 at regular predetermined intervals). The monitoring of the resistance may be carried out by implementing the same or similar methods set out above in relation to Figs. 5 and 7. Operation 702 may be the same operation as operation 602 of the method 600 in Fig. 9.

[0335] The method 700 further comprises, in an operation 704, determining a rate of change of the resistance of the heating element 112, 312 over time, for example by carrying out a numerical differentiation of the determined instantaneous resistances over time. Operation 704 may be the same operation as operation 604 of the method 600 in Fig. 9.

[0336] The method 700 further comprises, in an operation 706, comparing the determined rate of change to one of one or more intermediate thresholds (e.g., a lowest intermediate threshold of the one or more intermediate thresholds). The one or more intermediate thresholds may be individually calibrated for a specific aerosol-generating apparatus 1.

[0337] If the determined rate of change of the resistance of the heating element 112, 312 exceeds the intermediate threshold under consideration, the method 700 proceeds to operation 708, in which it is determined that the mass of the consumable 70 is less than a corresponding mass threshold.

[0338] The method 700 may further comprise, in an operation 710, determining whether the intermediate threshold under consideration is a refill threshold (e.g., a highest of the one or more intermediate thresholds). The refill threshold may also be referred to equivalently as a depletion threshold (i.e., a threshold indicative that the consumable 70 is depleted).

[0339] If the intermediate threshold under consideration is the refill threshold, the method 700 may further comprise, in an operation 712, alerting a user of the aerosol-generating apparatus 1 that the consumable 70 of the aerosol-generating apparatus 1 is depleted and that the consumable 70 needs to be replaced (either immediately or in the near-future). The alert may, for example, take the form of an alarm (or other audible alert), a flashing orange / amber light (or other visible alert), or a vibration of the aerosol-generating apparatus 1 (or other haptic alert).

[0340] If the intermediate threshold under consideration is not the refill threshold, the method 700 may return to operation 706, comparing the determined rate of change of the resistance of the heating element 112, 312 with a next of the one or more intermediate thresholds (e.g., the next lowest intermediate threshold). In this way, the method 700 may iterate through each of the one or more intermediate thresholds to determine a depletion level of the consumable 70 of the aerosol-generating apparatus 1 (e.g., a mass of the consumable 70 or a range within which the mass of the consumable 70 lies).

[0341] In some examples (such as examples where method 600 depicted in Fig. 9 and the method 700 depicted in Fig. 10 are implemented concurrently in the same aerosol generating apparatus 1), if the intermediate threshold under consideration is the refill threshold, the method 700 may further comprise proceeding to operation 606 of Fig. 9 and comparing the determined rate of change of resistance of the heating element 112, 312 to the final threshold (and subsequently proceeding with the remaining operations of Fig. 6. In this way, A method may be provided that not only informs the user of when the consumable 70 is depleted, but also when the consumable 70 is not even installed in the aerosol generating apparatus 1.

[0342] If the determined rate of change of the resistance of the heating element 112, 312 does not exceed the intermediate threshold under consideration, the method 700 proceeds to operation 714, in which it is determined that the mass of the consumable 70 is more than the corresponding mass threshold.

[0343] The method 700 may further comprise, in an operation 716, providing a user of the aerosol generating apparatus 1 with an indication that the consumable is not depleted. The indication may, for example, take the form of a green light (or other visible indication). The indication may, for example, be the same indication as provided in operation 616 of the method 600 of Fig. 9.

[0344] After completing the iterations of operations 706 to 716 (e.g., after providing the user of the aerosol-generating apparatus with either (i) an alert that the consumable 70 is depleted or (ii) an indication that the consumable 70 is not depleted), the method 700 may proceed to operation 718, in which a power output level is adjusted in accordance with a determined mass (or mass range) of the consumable 70. To achieve this, operation 718 may involve selecting a power level from one or more predetermined power levels, each corresponding to one of the one or more intermediate thresholds. The selected power level, selected in operation 718, is the power level corresponding to the highest of the intermediate thresholds that the determined rate of change of resistance of the heating element 112, 312 exceeds. The power in each of the power levels is inversely proportional to the levels of the corresponding intermediate thresholds -that is, the higher the intermediate threshold, the lower the power output associated with the corresponding power level.

[0345] Upon selection of the selected power level, the aerosol-generating apparatus 1 applies the selected power level as power input to the heating element 112, 312 to induce or maintain aerosolization of the consumable 70 by the heating element 112, 312. By reducing the power input to the heating element 112, 312 as the mass of the consumable 70 is depleted, a more consistent user experience is provided to a user of the aerosol-generating apparatus.

[0346] The method 700 may be repeated (or iterated) to provide a continuous or near-continuous monitoring of the rate of change of resistance of the heating element 112, 312 over time, and to provide a continuous or near-continuous monitoring of the mass of a consumable 70 installed in the aerosol-generating apparatus 1.

[0347] Alternatively, the method 700 may be carried out upon activation or initialisation of the aerosol-generating apparatus 1 - e.g., as part of a start-up sequence of the aerosol-generating apparatus 1.

Examples

Embodiment Construction

[0212]Before describing several examples implementing the present disclosure, it is to be understood that the present disclosure is not limited by specific construction details or process steps set forth in the following description and accompanying drawings. Rather, it will be apparent to those skilled in the art having the benefit of the present disclosure that the systems, apparatuses and / or methods described herein could be embodied differently and / or be practiced or carried out in various alternative ways.

[0213]Unless otherwise defined herein, scientific and technical terms used in connection with the presently disclosed inventive concept(s) shall have the meanings that are commonly understood by those of ordinary skill in the art, and known techniques and procedures may be performed according to conventional methods well known in the art and as described in various general and more specific references that may be cited and discussed in the present specification.

[0214]Any paten...

FIELD

[0001] The present disclosure relates to an aerosol generating apparatus and a method of operating the same.BACKGROUND

[0002] A typical heat-not-burn, HNB, aerosol generating apparatus may comprise a power supply, a heating element that is driven by the power supply, an aerosol precursor, which in use is aerosolised by the aerosol generating unit to generate an aerosol, and a delivery system for delivery of the aerosol to a user.

[0003] A drawback with known HNB aerosol generating apparatuses is that the power consumption of the heating element may evolve over time and / or vary between nominally identical HNB aerosol generating apparatuses. This may result in an inconsistent aerosol generation and consequently an inconsistent user experience for a user of the HNB aerosol generating apparatus.

[0004] In spite of the effort already invested in the development of aerosol generating apparatuses / systems further improvements are desirable.SUMMARY

[0005] In a first aspect, the present disclosure provides a method of operating a heat-not-burn, HNB, aerosol generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a measurement resistor having a predetermined resistance electrically connected in series. The method comprises: applying, by a power supply, an electrical signal across the heating element and the measurement resistor; determining, based on a measurement of the applied electrical signal an instantaneous power consumption of the heating element; determining, using the instantaneous power consumption of the heating element, an ON proportion of a time period, such that, when the heating element is activated for the ON proportion of the time period, a target average power consumption by the heating element over the time period is achieved; and applying a supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption.

[0006] In some embodiments, there may be provided a method of operating a heat-not-burn, HNB, aerosol generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a measurement resistor having a predetermined resistance electrically connected in series to define a potential divider. The method comprises: applying a supply voltage, by a power supply, across the resistor and the heating element for an initial period; measuring a midpoint voltage between the measurement resistor and the heating element; determining an instantaneous power consumption of the heating element based on the measured midpoint voltage; determining, using the instantaneous power consumption of the heating element, an ON proportion of a time period, such that, when the heating element is activated for the ON proportion of the time period a target average power consumption by the heating element over the time period is achieved; and applying the supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption.

[0007] By operating the HNB aerosol generating apparatus in this manner, it may be possible to ensure that the average power consumption of the heating element is consistent. In this manner, the HNB aerosol generating apparatus may be able to generate aerosol under activation of the heating element in a consistent manner, thereby providing the user of the HNB aerosol generating apparatus with a consistent user experience.

[0008] In some examples, the heating element may be a resistive heating element. For example, the heating element may be a heater that is heated as a result of the heater's resistance to electrical current passing through the heater.

[0009] In some examples, the resistor having a predetermined resistance may be referred to interchangeably and without limitation, as a measurement resistor or a sense resistor.

[0010] In some examples, the power supply may be configured to provide a fixed voltage, said fixed voltage being the supply voltage. Alternatively, the power supply may be configured to provide a variable voltage, with the supply voltage being a selected voltage from within an operating range of the power supply. In some examples, on demand, or in response to one or more predetermined criteria being satisfied, the power supply may be configured to boost the voltage of the supply voltage to a higher level, for example, to compensate for an instantaneous drop or dip in the temperature of the heating element. For example, by inhaling and drawing air through the HNB aerosol generating apparatus, the user may draw air over a surface of the heating element, thereby cooling the heating element. This may cause a decrease in the efficiency of any aerosol generation by the heating element that may be compensated for by boosting a power supply to the heating element to a relatively higher level.

[0011] In some examples, the midpoint voltage may be understood as being a midpoint (or output) voltage of the potential divider. Accordingly, an instantaneous resistance of the heating element may be determinable by the skilled person using known analysis techniques relating to potential dividers.

[0012] In some examples, the instantaneous power consumption of the heating element may be determined, at least in part, by inferring the instantaneous resistance of the heating element from the values of the predetermined resistance, the applied supply voltage, and the measured midpoint voltage.

[0013] In some examples, applying the supply voltage across the resistor and the heating element may comprise applying a constant supply voltage for the initial period.

[0014] In some examples, applying the supply voltage across the heating element to achieve the target average power consumption may comprise applying the supply voltage with a top-hat, or step profile, wherein the top-hat or step may be defined with an upper voltage value equal to the supply voltage applied during the initial period, and a lower voltage value equal to 0 V.

[0015] In some examples, the initial period may be 15 ms or less, 10 ms or less, 5 ms or less, or 2 ms or less. Alternatively, the initial period may be 1 ms or more, 2 ms or more, 5 ms or more, or 10 ms or more. Alternatively, the initial period may be between 1 and 15 ms, 1 and 10 ms, 1 and 5 ms, 1 and 2 ms, 2 and 15 ms, 2 and 10 ms, 2 and 5 ms, 5 and 15 ms, 5 and 10 ms, or 10 and 15 ms.

[0016] In a particular example, the initial period is 5 ms. In some examples, the measuring of the midpoint voltage, and determining the instantaneous power consumption and the ON proportion of the time period may be instantaneous, or at least substantially instantaneous (i.e., negligible in relation to the duration of the initial period). For example, the amount of time required to measure the midpoint voltage (or any other electrical property of the voltage / current) may be approximately 100 µs.

[0017] In some examples, the time period may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the time period may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the time period may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0018] In a particular example, the time period may be 20 ms, the first 5 ms of which may be the initial period.

[0019] In some examples, the initial period may be a part of the time period. In other words, the application of the supply voltage for the initial period, and the determination of the ON proportion of the time period for which the heating element needs to be activated to achieve the target average power consumption may be carried out at the beginning of the time period. For example, the voltage applied during the time period may be defined by a step profile. The step profile may be defined by an upper voltage value equal to the supply voltage that transitions to a lower voltage value equal to 0 V. The portion of the step profile defined by the upper voltage may comprise two parts, a first part that is the initial period, and a second part that is the remainder of the upper voltage portion between the initial period and the transition to the lower voltage value. The transition to the lower voltage value may occur at the end of the determined ON proportion of the time period.

[0020] In some embodiments, the method may be cyclically repeated during operation of the HNB aerosol-generating apparatus.

[0021] For example, the carrying out of the method may be cyclically repeated every 5 ms, 10 ms, 20 ms, 30 ms, 50 ms, or 100 ms. For example, the carrying out of the method may be cyclically repeated on a continuous basis such that there is no delay between consecutive time periods.

[0022] In a particular example, the method is cyclically repeated every 20 ms.

[0023] As the power consumption of the heating element impacts the generation of aerosol by the heating element (indirectly by impacting the temperature of the heating element), by keeping the time period (and the cyclical repetition period) short, relative to a user's perception, the user may not perceive variations in the quality of the aerosol generated and delivered to the user by the aerosol-generating apparatus. The quality of the aerosol may include one or more of a quantity, temperature, concentration, and / or consistency of an aerosol generated by the aerosol-generating apparatus.

[0024] In some embodiments, the resistor may be connected between the power supply and the heating element.

[0025] In this way, the midpoint voltage may be a representation of the voltage drop across the resistor.

[0026] Alternatively, the heating element may be connected between the power supply and the resistor. In such examples, the midpoint voltage may be a representation of the voltage drop across the heating element.

[0027] In some embodiments, the resistor may be switchably connected in series with the heating element such that the supply voltage is not applied across the resistor when applying the supply voltage across the heating element for the determined ON proportion of the time period to achieve the target average power consumption. For example, during at least part (and, in some examples, all) of the ON proportion of the time period, the measurement resistor may be bypassed. For the avoidance of doubt, power is applied across the heating element during both the initial period and the determined ON proportion of the time period. The determined ON proportion of the time period may be considered, in at least some examples, to be the amount of time (when considered in addition to the initial period) for which it is necessary to apply the supply voltage across the heating element in order to achieve the target average power consumption.

[0028] In this way, voltage consumption across the resistor may be limited only to the measurement period. In other words, power may only be dissipated through the resistor for sufficient time to determine the instantaneous power consumption of the heating element and the ON proportion of the time period for which the heating element needs to be activated to achieve the target average power consumption by the heating element over the time period.

[0029] In some embodiments, the HNB aerosol-generating apparatus may comprise a circuit connecting the power supply to the heating element. The circuit may comprise two circuit paths. The first circuit path may be switchably connectable path with the power supply and may comprise the resistor. The second circuit path may be switchably connectable path with the power supply and may be arranged to bypass the resistor. Applying the supply voltage across the resistor and the heating element may involve switchably connecting the first circuit path and switchably disconnecting the second circuit path. Applying the supply voltage across the heating element and not the resistor may involve switchably connecting the second circuit path and switchably disconnecting the first circuit path.

[0030] In this way, the resistor may be connected and disconnected from the power supply on an as needed basis for the purpose of measuring the midpoint voltage, determining the instantaneous power consumption of the heating element, and determining the ON proportion of the time period for which the heating element needs to be activated to achieve a target average power consumption by the heating element over the time period.

[0031] The resistor may be switchably connected to the power supply for some or all of the measurement period. In some examples, the resistor may be switchably connected only briefly, even instantaneously, during the measurement period before being disconnected to avoid unnecessary dissipation of power through the resistor.

[0032] In some embodiments, the first and / or second circuit paths may be switchably connected to the power supply by a respective field-effect transistor, FET, switch.

[0033] FET switches may be advantageous as their switching time can be significantly shorter than either the time period or the measurement period of the methods described herein. In other words, the switching time of the FET switches may be considered to be functionally instantaneous meaning that the switchable connections and disconnections of the first and / or second circuit paths does not impact the smoothness of the power / voltage delivery to the heating element, or at least the user's perception of the smoothness of the power / voltage delivery to the heating element.

[0034] In some examples, any one or more of the one or more FET switches may be a MOSFET switch. In some examples, any one or more of the one or more FET switches may be either a P-channel or a N-channel FET, or a P-channel or N-channel MOSFET.

[0035] In some examples, a circuit connecting the power supply to ground via the measurement resistor and the heating element may comprise one or more P-channel FET (or MOSFET) switches between the measurement resistor and the power supply and / or between the heating element and the power supply. In some examples, said circuit may further comprise one or more N-channel FET (or MOSFET switches) between the heating element and ground.

[0036] In some embodiments, the predetermined resistance may be within a predetermined range from a nominal resistance of the heating element.

[0037] The nominal resistance of the heating element may be understood to be a standard, expected or representative resistance of the heating element. For example, the nominal resistance may be an expected resistance provided by a manufacturer of the heating element when the heater is at room temperature. In some examples, the nominal resistance may be a midpoint of an expected operating resistance range provided by a manufacturer of the heating element, the expected operating resistance range being a range of possible resistance values for the resistance of the heating element that are within a manufacturing tolerance of the heating element.

[0038] In some examples, the nominal resistance of the heating element may be updated over time, for example, in response to a resistance of the heating element changing over time (e.g., due to operation of the heating element). For example, a resistance of the heating element at room temperature of the heating element may change over time, e.g., due to deterioration of one or more components of the heating element, or there may be a long-term gradual drift in the nominal resistance of the heating element that may be compensated for.

[0039] In some examples, the nominal resistance of the heating element may be 2 Ω or less, 1.8 Ω or less, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the nominal resistance of the heating element may be 0.2 Ω or more, 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 1.8 Ω or more. In some examples, the nominal resistance of the heating element may be between 0.2 and 2 Ω, 0.2 and 1.8 Ω, 0.2 and 1.5 Ω, 0.2 and 1 Ω, 0.2 and 0.5 Ω, 0.5 and 2 Ω, 0.5 and 1.8 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.8 Ω, 1 and 1.5 Ω, 1.5 and 2 Ω, 1.5 and 1.8 Ω, or 1.8 and 2 Ω.

[0040] In a particular example, the nominal resistance of the heating element may be between 0.2 and 1.8 Ω.

[0041] In a particular example, the nominal resistance of the heating element may be 1.1 ± 0.1 Ω.

[0042] In some examples, the measurement resistor may be a fixed resistance resistor. Alternatively, in some examples, the measurement resistor may be a variable resistor. The predetermined resistance may, in some examples, be varied to ensure that the predetermined resistance remains within the predetermined range from the nominal resistance of the heating element as the nominal resistance evolves over the lifetime of the heating element.

[0043] The predetermined resistance being within the predetermined range from the nominal resistance may be understood to mean that the difference between the predetermined resistance and the nominal resistance may be less than a predetermined percentage of the nominal resistance.

[0044] The predetermined percentage may, for example, be 100% or less, 75% or less, 50% or less, 25% or less, or 10% or less. The predetermined percentage may, for example, be 10% or more, 25% or more, 50% or more, 75% or more, or 100% or more. The predetermined percentage may, for example, be between 10 and 100%, 10 and 75 %, 10 and 50%, 10 and 25 %, 25 and 100%, 25 and 75%, 25 and 50%, 50 and 100%, 50 and 75%, or 75 and 100%.

[0045] Alternatively, the predetermined resistance being within the predetermined range from the nominal resistance may be understood to mean that the difference between the predetermined resistance and the nominal resistance may be less than a predetermined difference threshold.

[0046] The predetermined difference threshold may, for example, be 2 Ω or less, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the predetermined difference threshold may be 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 2 Ω or more. In some examples, the predetermined difference threshold may be between 0.5 and 2 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.5 Ω, or 1.5 and 2 Ω.

[0047] In some examples, the predetermined resistance of the resistor may be 2 Ω or less, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the predetermined resistance may be 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 2 Ω or more. In some examples, the predetermined resistance may be between 0.5 and 2 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.5 Ω, or 1.5 and 2 Ω.

[0048] In a particular example, the predetermined resistance may be 1.6 Ω.

[0049] By ensuring that the predetermined resistance of the measurement resistor is within a predetermined range from the nominal resistance of the heating element (i.e., that the predetermined resistance and nominal resistance are similar), a larger dynamic range of the midpoint voltage measurement is facilitated, thereby making the measurement of the midpoint voltage more sensitive to differences between the predetermined resistance and a resistance of the heating element.

[0050] In some embodiments, the method may further comprise measuring the supply voltage supplied across the measurement resistor and the heating element.

[0051] Alternatively, in some examples, the supply voltage may be a known supply voltage, or a voltage set by the user of the HNB aerosol-generating apparatus, or a voltage set by a control unit or processor of the HNB aerosol-generating apparatus.

[0052] In some embodiments, measuring the midpoint voltage may be carried out after a predetermined settling time has elapsed after beginning to apply the supply voltage across the heating element.

[0053] In some embodiments, measuring the supply voltage may be carried out after the predetermined settling time has elapsed after beginning to apply the supply voltage across the heating element.

[0054] When a voltage is applied across the heating element (e.g., at the commencement of the time period and / or at the commencement of the initial period), the supply voltage may drop as a result of the resistive load of the heating element. To ensure a more accurate control of the power consumption of the heating element (e.g., improving the accuracy of attaining the target average power consumption), it may be beneficial to wait for the supply voltage to drop and settle at a consistent "under-load" voltage level. The amount of time to wait for the supply voltage to drop and settle at the under-load voltage level is referred to herein as the settling time.

[0055] In some examples, the settling time may be a part of the initial period.

[0056] In some examples, the settling time may be 10 ms or less, 7 ms or less, 5 ms or less, or 2 ms or less. In some examples, the settling time may be 2 ms or more, 5 ms or more, 7 ms or more , or 10 ms or more. In some examples, the settling time may be between 2 and 10 ms, 2 and 7 ms, 2 and 5 ms, 5 and 10 ms, 5 and 7 ms, or 7 and 10 ms.

[0057] In a particular example, the settling time may be between 2 and 7 ms.

[0058] In a particular example, the settling time may be 5 ms. In some examples, the measuring of the midpoint voltage, and determining the instantaneous power consumption and the ON proportion of the time period may be instantaneous, or at least substantially instantaneous (i.e., negligible in relation to the settling time). For example, the amount of time required to measure the midpoint voltage (or any other electrical property of the voltage / current) may be approximately 100 µs.

[0059] In some embodiments, applying the supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption may involve: applying the supply voltage, by the power supply, across the heating element for a first continuous portion of the time period equal to the ON proportion; and not applying the supply voltage for a second continuous portion if the time period equal to the remainder of the time period.

[0060] In other words, the temporal profile of the supply voltage applied across the heating element may be defined by a step-down profile as described above.

[0061] In some embodiments, the method may further comprise: selecting an operation mode of the HNB aerosol-generating apparatus from amongst a plurality of operation modes. Each operation mode may require a respective power consumption. The target average power consumption may be a respective power consumption corresponding to the selected operation mode of the HNB aerosol-generating apparatus.

[0062] In some examples, the HNB aerosol-generating apparatus may be operable in a plurality of different operation modes. For example, the HNB aerosol-generating apparatus may be useable with a plurality of different precursors, each of which may be configured to generate an aerosol from the precursor upon the application of heat to a corresponding temperature. Each operating mode of the HNB aerosol-generating apparatus may therefore correspond to a respectively different target heating temperature that is suitable for activating a corresponding precursor to generate aerosol (e.g., for inhalation by the user). As such, each operating mode of the HNB aerosol-generating apparatus may correspond with a respectively different target average power consumption of the heating element in order to achieve the corresponding target heating temperature. Additionally or alternatively, heating a same precursor to one of a set of different temperatures may result in the generation of different quantities and / or concentrations of aerosol from the same precursor. In other words, a higher temperature may be used to deliver an aerosol that provides a user of the aerosol-generating apparatus with a more intense user experience (e.g., because the delivered aerosol is more potent, and / or generated in higher quantities and / or concentrations). As such, the plurality of different operation modes may correspond with respectively different target average power consumptions of the heating element in order to achieve a desired user experience for a user of the aerosol-generating apparatus.

[0063] In some embodiments, determining the instantaneous power consumption of the heating element may comprise: determining a voltage ratio between the supply voltage and the midpoint voltage; determining the instantaneous resistance of the heating element using the voltage ratio and the predetermined resistance; and determining the instantaneous power consumption of the heating element using the measured midpoint voltage and the determined instantaneous resistance of the heating element. The determined voltage ratio may be equal to a resistance ratio between the predetermined resistance and an instantaneous resistance of the heating element.

[0064] In some embodiments, determining the ON proportion of the time period may comprise: determining a ratio between the target average power consumption and the determined instantaneous power consumption; adjusting the ratio to account for electrical losses in a circuit comprising the power supply and the heating element; and applying the adjusted ratio to the time period to determine the ON proportion of the time period.

[0065] In this way, losses in the power delivered by the power supply may be accounted for such that the target average power consumption may be reliably and accurately achieved.

[0066] As an illustrative example, that is not intended to be limiting in the context of the present disclosure, if the adjusted ratio was indicative that the instantaneous power consumption of the heating element was double the target average power consumption, then the ON proportion of the time period would be determined to be half the total length of the time period. In other words, the ON proportion of the time period is determined in a manner that is inversely proportional to the ratio of the target average power consumption to the instantaneous power consumption.

[0067] In another aspect, there is provided a heat-not-burn, HNB, aerosol-generating apparatus comprising: a heating element configured to heat an aerosol precursor; a power supply configured to supply electrical current to the heating element; a measurement resistor having a predetermined resistance; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out the methods described herein. The heating element is heatable by flowing electrical current therethrough.

[0068] In another aspect there may be provided a computer-readable medium, or a computer program comprising logic and / or instructions that, when executed by a processor of a HNB aerosol-generating apparatus, cause the HNB aerosol-generating apparatus to carry out the methods described herein.

[0069] In some embodiments, there may be provided a method of operating a heat-not-burn, HNB, aerosol-generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a measurement resistor having a predetermined resistance electrically connected in series. The method comprises: supplying, by a power supply, a current through the resistor and the heating element; measuring the current passing through the resistor; determining an instantaneous power consumption of the heating element based on the measured current; determining, using the instantaneous power consumption of the heating element, an ON proportion of a time period such that, when the heating element is activated for the ON proportion of the time period a target average power consumption by the heating element over the time period is achieved; and applying a supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption.

[0070] In some examples, the supply voltage may be the same electrical supply as the current supplied by the power supply through the measurement resistor and the heating element.

[0071] By operating the HNB aerosol generating apparatus in this manner, it may be possible to ensure that the average power consumption of the heating element is consistent. In this manner, the HNB aerosol-generating apparatus may be able to generate aerosol under activation of the heating element in a consistent manner, thereby providing the user of the HNB aerosol generating apparatus with a consistent user experience.

[0072] In some examples, the heating element may be a resistive heating element. For example, the heating element may be a heater that is heated as a result of the heater's resistance to electrical current passing through the heater.

[0073] In some examples, the measurement resistor may be referred to interchangeably and without limitation, as a sense resistor.

[0074] In some examples, the power supply may be configured to provide a fixed current and / or voltage, said fixed current being the current supplied through the measurement resistor and the heating element, and / or said voltage being the supply voltage. Alternatively, the power supply may be configured to provide a variable voltage, with the supply voltage being a selected voltage from within an operating range of the power supply. Additionally or alternatively, the power supply may be configured to provide a variable current, with the current supplied through the measurement resistor and the heating element being a selected current form within an operating range of the power supply. In some examples, on demand, or in response to one or more predetermined criteria being satisfied, the power supply may be configured to boost the voltage of the supply voltage (or the current supplied through the resistor and the heating element) to a higher level, for example, to compensate for an instantaneous drop or dip in the temperature of the heating element. For example, by inhaling and drawing air through the HNB aerosol generating apparatus, the user may draw air over a surface of the heating element, thereby cooling the heating element. This may cause a decrease in the efficiency of any aerosol generation by the heating element that may be compensated for by boosting a power supply to the heating element to a relatively higher level.

[0075] In some examples, the instantaneous power consumption may be determined, at least in part, by inferring the instantaneous resistance of the heating element from the values of the supply voltage and the measured current.

[0076] In some examples, applying the supply voltage across the heating element to achieve the target average power consumption may comprise applying the supply voltage with a top-hat, or step profile, wherein the top-hat or step may be defined with an upper voltage value equal to the supply voltage applied during an initial period, and a lower voltage value equal to 0 V.

[0077] In some examples, the time period may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the time period may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the time period may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0078] In a particular example, the time period is 20 ms.

[0079] In some embodiments, the method may be cyclically repeated during operation of the HNB aerosol-generating apparatus.

[0080] For example, the carrying out of the method may be cyclically repeated every 5 ms, 10 ms, 20 ms, 30 ms, 50 ms, or 100 ms. For example, the carrying out of the method may be cyclically repeated on a continuous basis such that there is no delay between consecutive time periods.

[0081] In a particular example, the method is cyclically repeated every 20 ms.

[0082] As the power consumption of the heating impacts the generation of aerosol by the heating element (indirectly by impacting the temperature of the heating element), by keeping the time period (and the cyclical repetition period) short, relative to a user's perception, the user may not perceive variations in the quality of the aerosol generated and delivered to the user by the aerosol-generating apparatus. The quality of the aerosol may include one or more of a quantity, temperature, concentration, and / or consistency of an aerosol generated by the aerosol-generating apparatus.

[0083] In some embodiments, the predetermined resistance may be less than a nominal resistance of the heating element.

[0084] The nominal resistance of the heating element may be understood to be a standard, expected or representative resistance of the heating element. For example, the nominal resistance may be an expected resistance provided by a manufacturer of the heating element when the heater is at room temperature. In some examples, the nominal resistance may be a midpoint of an expected operating resistance range provided by a manufacturer of the heating element, the expecting operating resistance being a range of possible resistance values of the resistance of the heating element that are within a manufacturing tolerance of the heating element.

[0085] In some examples, the nominal resistance of the heating element may be updated over time, for example, in response to a resistance of the heating element changing over time (e.g., due to operation of the heating element). For example, a resistance of the heating element at room temperature heating element may change over time, e.g., due to deterioration of one or more components of the heating element, or there may be a long-term gradual drift in the nominal resistance of the heating element that may be compensated for.

[0086] In some examples, the nominal resistance of the heating element may be 2 Ω or less, 1.8 Ω or more, 1.5 Ω or less, 1 Ω or less, or 0.5 Ω or less. In some examples, the nominal resistance of the heating element may be 0.2 Ω or more, 0.5 Ω or more, 1 Ω or more, 1.5 Ω or more, or 1.8 Ω or more. In some examples, the nominal resistance of the heating element may be between 0.2 and 2 Ω, 0.2 and 1.8 Ω, 0.2 and 1.5 Ω, 0.2 and 1 Ω, 0.2 and 0.5 Ω, 0.5 and 2 Ω, 0.5 and 1.8 Ω, 0.5 and 1.5 Ω, 0.5 and 1 Ω, 1 and 2 Ω, 1 and 1.8 Ω, 1 and 1.5 Ω, 1.5 and 2 Ω, 1.5 and 1.8 Ω, or 1.8 and 2 Ω.

[0087] In a particular example, the nominal resistance of the heating element may be between 0.2 and 1.8 Ω.

[0088] In a particular example, the nominal resistance of the heating element may be 1.1 ± 0.1 Ω.

[0089] In some examples, the measurement resistor may be a fixed resistance resistor. Alternatively, in some examples, the measurement resistor may be a variable resistor. The predetermined resistance may, in some examples, be varied to ensure that the predetermined resistance remains lower than the nominal resistance of the heating element.

[0090] In some examples, the predetermined resistance may be at least 5 times less than the nominal resistance, at least 10 times less than the nominal resistance, at least 20 times less than the nominal resistance, at least 50 times less than the nominal resistance, at least 100 times less than the nominal resistance, at least 250 times less than the nominal resistance, or at least 500 times less than the nominal resistance.

[0091] In some embodiments, the predetermined resistance may be at least 10 times less than the nominal resistance.

[0092] In some embodiments, the predetermined resistance may be at least 100 times less than the nominal resistance.

[0093] In some examples, the predetermined resistance may be 100 mΩ or less, 50 mΩ or less, 10 mΩ or less, 5 mΩ or less, or 1 mΩ or less. In some examples, the predetermined resistance may be 1 mΩ or more, 5 mΩ or more, 10 mΩ or more, or 50 mΩ or more. In some examples, the predetermined resistance may be between 1 and 100 mΩ, between 1 and 50 mΩ, between 1 and 10 mΩ, between 1 and 5 mΩ, between 5 and 100 mΩ, between 5 and 50 mΩ, between 5 and 10 mΩ, between 10 and 100 mΩ, between 10 and 50 mΩ, or between 50 and 100 mΩ.

[0094] By ensuring that the predetermined resistance is less than the nominal resistance of the heating element (and, optionally, significantly less than the nominal resistance), it may be possible to facilitate a negligible power consumption by the measurement (or sense) resistor. In this way, it may be possible to assume that there is a negligible volage drop across the measurement (or sense) resistor, and therefore that all, or substantially all, of the supply voltage, at least in a practical sense, is supplied across the heating element.

[0095] In some embodiments, measuring the current passing through the measurement resistor may comprise using a current sense amplifier to measure the current.

[0096] A current sense amplifier may be suitable for use in the context of the methods described herein to measure the current passing through the resistor by amplifying a voltage drop across the measurement (or sense) resistor to a larger voltage thereby increasing the resolution and dynamic range of the current measurement.

[0097] In some examples, the current sense amplifier may have a gain functionality to implement a gain of the voltage drop across the measurement (or sense) resistor. In some examples the gain may be a fixed gain. Alternatively, the gain may be a variable gain that is adjustable by a user of the HNB aerosol generating apparatus, or by a control unit or processor of the HNB aerosol generating apparatus.

[0098] In some examples, the gain of the current sense amplifier may be 10 or more, 20 or more, 50 or more 100 or more, 250 or more, or 500 or more. In some examples, the gain of the current sense amplifier may be 500 or less, 250 or less, 100 or less, 50 or less, 20 or less, or 10 or less. In some examples, the gain of the current sense amplifier may be between 10 and 500, between 10 and 250, between 10 and 50, between 10 and 20, between 20 and 500, between 20 and 250, between 20 and 100, between 20 and 50, between 50 and 500, between 50 and 250, between 50 and 100, between 100 and 500, between 100 and 250, or between 250 and 500.

[0099] In a particular example, the gain of the current sense amplifier may be between 50 and 200. In a particular example, the gain of the current sense amplifier may be 50. In a particular example, the gain of the current sense amplifier may be 200.

[0100] In some embodiments, the method may further comprise measuring the supply voltage supplied across the measurement resistor and the heating element. Determining the instantaneous power consumption of the heating element may involve using the measured current and the measured supply voltage.

[0101] Alternatively, in some examples, the supply voltage may be a known supply voltage, or a voltage set by the user of the HNB aerosol-generating apparatus, or a voltage set by a control unit or processor of the HNB aerosol-generating apparatus.

[0102] In some embodiments, measuring the current may be carried out after a predetermined settling time has elapsed after beginning to apply the current through the measurement resistor and the heating element.

[0103] In some embodiments, measuring the supply voltage may be carried out after the predetermined settling time has elapsed after beginning to apply the current through the measurement resistor and the heating element.

[0104] When a voltage or current is applied across or through the heating element (e.g., at the commencement of the time period), the supply voltage / current may drop as a result of the resistive load of the heating element. In order to ensure a more accurate control of the power consumption of the heating element (e.g., improving the accuracy of attaining the target average power consumption), it may be beneficial to wait for the supply voltage / current to drop and settle at a consistent "under-load" voltage level. The amount of time to wait for the supply voltage / current to drop and settle at the under-load voltage level is referred to herein as the settling time.

[0105] In some examples, the settling time may be 10 ms or less, 7 ms or less, 5 ms or less, or 2 ms or less. In some examples, the settling time may be 2 ms or more, 5 ms or more, 7 ms or more , or 10 ms or more. In some examples, the settling time may be between 2 and 10 ms, 2 and 7 ms, 2 and 5 ms, 5 and 10 ms, 5 and 7 ms, or 7 and 10 ms.

[0106] In a particular example, the settling time may be between 2 and 7 ms.

[0107] In a particular example, the settling time may be 5 ms.

[0108] In some embodiments, the heating element may be switchably connected to the power supply.

[0109] In some examples, the heating element may be swithcably connected to the power supply by one or more field-effect, FET, switches.

[0110] FET switches may be advantageous as their switching time can be significantly shorter than either the time period or the measurement period of the methods described herein. In other words, the switching time of the FET switches may be considered to be functionally instantaneous meaning that the switchable connections and disconnections of the FET switches do not impact the smoothness of the power / voltage delivery to the heating element, or at least the user's perception of the smoothness of the power / voltage delivery to the heating element.

[0111] In some examples, any one or more of the one or more FET switches may be a MOSFET switch. In some examples, any one or more of the one or more FET switches may be either a P-channel or a N-channel FET, or a P-channel or N-channel MOSFET.

[0112] In some examples, a circuit connecting the power supply to ground via the measurement resistor and the heating element may comprise one or more P-channel FET (or MOSFET) switches between the measurement resistor and the power supply and / or between the heating element and the power supply. In some examples, said circuit may further comprise one or more N-channel FET (or MOSFET switches) between the heating element and ground.

[0113] In some embodiments, applying the supply voltage, by the power supply, across the heating element for the ON proportion of the time period to achieve the target average power consumption may involve: applying the supply voltage, by the power supply, across the heating element for a first continuous portion of the time period equal to the ON proportion; and preventing the supply of the supply voltage for a second, subsequent, continuous portion of the time period equal to the remainder of the time period.

[0114] In other words, the temporal profile of the supply voltage applied across the heating element may be defined by a step-down profile as described above.

[0115] In some embodiments, the method may further comprise: selecting an operation mode of the HNB aerosol-generating apparatus from amongst a plurality of operation modes. Each operation mode may require a respective power consumption. The target average power consumption may be a respective power consumption corresponding to the selected operation mode of the HNB aerosol-generating apparatus.

[0116] In some examples, the HNB aerosol-generating apparatus may be operable in a plurality of different operation modes. For example, the HNB aerosol-generating apparatus may be useable with a plurality of different precursors, each of which may be configured to generate an aerosol from the precursor upon the application of heat to a corresponding temperature. Each operating mode of the HNB aerosol-generating apparatus may therefore correspond to a respectively different target heating temperature that is suitable for activating a corresponding precursor to generate aerosol (e.g., for inhalation by the user). As such, each operating mode of the HNB aerosol-generating apparatus may correspond with a respectively different target average power consumption of the heating element in order to achieve the corresponding target heating temperature. Additionally or alternatively, heating a same precursor to one of a set of different temperatures may result in the generation of different quantities and / or concentrations of aerosol from the same precursor. In other words, a higher temperature may be used to deliver an aerosol that provides a user of the aerosol-generating apparatus with a more intense user experience (e.g., because the delivered aerosol is more potent, and / or generated in higher quantities and / or concentrations). As such, the plurality of different operation modes may correspond with respectively different target average power consumptions of the heating element in order to achieve a desired user experience for a user of the aerosol-generating apparatus.

[0117] In some embodiments, determining the instantaneous power consumption of the heating element may comprise: estimating a voltage drop across the heating element as being equal to the supply voltage; and determining the instantaneous power consumption of the heating element as the product of the voltage drop and the measured current.

[0118] In other words, in cases where the predetermined resistance of the measurement resistor is negligible relative to the instantaneous resistance of the heating element, it may be practically feasible to assume that all (or substantially all) of the power output by the power supply is depleted / consumed / dissipated by the heating element, and not by the measurement resistor. As such, the instantaneous power consumption of the heating element may be approximated using the standard relation that power consumption is equal to the product of the current flowing through a circuit element with the voltage drop across said circuit element.

[0119] In some embodiments, determining the ON proportion of the time period may comprise: determining a ratio between the target average power consumption and the determined instantaneous power consumption; adjusting the ratio to account for electrical losses in a circuit comprising the power supply and the heating element; and applying the adjusted ratio to the time period to determine the ON proportion of the time period.

[0120] In this way, losses in the power delivered by the power supply may be accounted for such that the target average power consumption may be reliably and accurately achieved.

[0121] As an illustrative example, that is not intended to be limiting in the context of the present disclosure, if the adjusted ratio was indicative that the instantaneous power consumption of the heating element was double the target average power consumption, then the ON proportion of the time period would be determined to be half the total length of the time period. In other words, the ON proportion of the time period is determined in a manner that is inversely proportional to the ratio of the target average power consumption to the instantaneous power consumption.

[0122] In another aspect, there is provided a heat-not-burn, HNB, aerosol-generating apparatus comprising: a heating element configured to heat an aerosol precursor; a power supply configured to supply electrical current to the heating element; a measurement resistor having a predetermined resistance; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out any of the methods described herein. The heating element is heatable by flowing electrical current therethrough.

[0123] In another aspect there may be provided a computer-readable medium, or a computer program comprising logic and / or instructions that, when executed by a processor of a HNB aerosol-generating apparatus, cause the HNB aerosol-generating apparatus to carry out the methods described herein.

[0124] In an aspect, there is provided a method of operating a heat-not-burn, HNB, aerosol-generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a power supply for supplying power to the heating element. The method comprises: monitoring a temperature of the heating element during operation of the HNB aerosol-generating apparatus. The monitoring comprises consecutively determining an instantaneous operational parameter value of the heating element to form a sequence of instantaneous operational parameter values of the heating element. The method further comprises determining a rolling average value of the operational parameter of the heating element based on the sequence of instantaneous operational parameter values; determining a difference between one instantaneous operational parameter value of the sequence of instantaneous operational parameter values and the determined rolling average value; and, if the determined difference exceeds a predetermined difference threshold, boosting a power output from a default power level to a relatively higher boosted power level of the power supply to supply the boosted power level to the heating element.

[0125] In some examples, the operational parameter may be a resistance of the heating element. In such examples, the rolling average value may be a rolling average value of the resistance of the heating element.

[0126] In other words, each instantaneous operational parameter value may be an instantaneous resistance value, and the rolling average value may be a rolling average value of the resistance of the heating element.

[0127] In other examples, each determined instantaneous operational parameter value may be a directly determined temperature value (e.g., using a temperature sensor), or may correspond to any operational parameter from which the temperature of the heating element may be inferred.

[0128] When a user of an HNB aerosol generating apparatus draws (i.e., inhales) on a mouthpiece of the apparatus, air is drawn across a surface of the heating element. This cools the heating element, causing its temperature and resistance to drop in response to the airflow across the surface of the heating element. Without intervention, the heating element may require anywhere from 10 to 20 seconds to recover back to its normal (or default) operational resistance and temperature. Therefore, boosting the power to more quickly recover the steady state operational temperature of the (resistive) heating element may advantageously facilitate a more consistent user experience for a user of the HNB aerosol-generating apparatus by ensuring that the steady-state / normal / default operation of the apparatus is resumed more quickly after drawing on the apparatus to inhale generated aerosol.

[0129] In some embodiments, boosting the power output may comprise boosting the power output for a predetermined boost period.

[0130] In some examples, the predetermined boost period may be 10 seconds or less, 5 seconds or less, 3 seconds or less, 1 second or less, or 0.5 seconds or less. In some examples, the predetermined boost period may be 0.5 seconds or more, 1 second or more, 3 seconds or more, 5 seconds or more, or 10 seconds or more. In some examples the predetermined boost period may be between 0.5 and 10 seconds, between 0.5 and 5 seconds, between 0.5 and 3 seconds, between 0.5 and 1 second, between 1 and 10 seconds, between 1 and 5 seconds, between 1 and 3 seconds, between 3 and 10 seconds, between 3 and 5 seconds, or between 5 and 10 seconds.

[0131] In a particular example, the predetermined boost period may be between 1 and 3 seconds.

[0132] In some examples, the predetermined difference threshold may be a difference between determined instantaneous resistance and the corresponding determined rolling average of 500 mΩ or less, 250 mΩ or less, 100 mΩ or less, 50 mΩ or less, 25 mΩ or less, or 10 mΩ or less. In some examples, the predetermined difference threshold may be a difference between determined instantaneous resistance and the corresponding determined rolling average of 10 mΩ or more, 25 mΩ or more, 50 mΩ or more, 100 mΩ or more, 250 mΩ or more, or 500 mΩ or more. In some examples, the predetermined difference threshold may be a difference between the determined instantaneous resistance and the determined rolling average of between 10 and 500 mΩ, between 10 and 250 mΩ, between 10 and 100 mΩ, between 10 and 50 mΩ, between 10 and 25 mΩ, between 25 and 500 mΩ, between 25 and 250 mΩ, between 25 and 100 mΩ, between 25 and 50 mΩ, between 50 and 500 mΩ, between 50 and 250 mΩ, between 50 and 100 mΩ, between 100 and 500 mΩ, between 100 and 250 mΩ, or between 250 and 500 mΩ.

[0133] In a particular example, the predetermined difference threshold may be a difference between determined instantaneous resistance and the corresponding determined rolling average of 50 mΩ.

[0134] In some embodiments, the difference threshold may be one of a plurality of difference thresholds and the boosted power level may be one of a plurality of boosted power levels. Each of the boosted power levels may correspond to one of the difference thresholds. Boosting the power output of the power supply may comprise: determining a highest of the plurality of difference thresholds that the determined difference exceeds; and boosting the power output of the power supply to supply the boosted power level corresponding to the determined highest of the plurality of difference thresholds.

[0135] In other words, the method may comprise boosting the power output of the power supply to a level that is proportional to the magnitude of the determined difference between one of the determined instantaneous resistance values and the determined rolling average value.

[0136] In this way, a variable (or graduated) level of control may be facilitated that allows a user to ensure that drops in the resistance / temperature of the heating element may be more efficiently mitigated (e.g., by more quickly returning the power consumption of the resistor to a normal, or standard, operating level).

[0137] In some embodiments, each of the plurality of boosted power levels may be proportional to the magnitude of the corresponding difference threshold.

[0138] In other words, the method may comprise boosting the power output of the power supply to a level that is proportional to the magnitude of the determined difference between one of the determined instantaneous resistance values and the determined rolling average value.

[0139] In this way, a variable (or graduated) level of control may be facilitated that allows a user to ensure that drops in the resistance / temperature of the heating element may be more efficiently mitigated (e.g., by more quickly returning the power consumption of the heating element to a normal, or standard, operating level).

[0140] In some embodiments, the consecutive determining of the instantaneous operational parameter values to form the sequence of instantaneous operational parameter values may be carried out at a predetermined interval.

[0141] In other words, a determination of a successive instantaneous operational parameter values may be carried out at the end of each predetermined interval - i.e., a time of length equal to the predetermined interval may pass between each consecutive determination of successive instantaneous operational parameter values.

[0142] In some examples, the predetermined interval may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the predetermined interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the predetermined interval may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0143] In a particular example, the predetermined interval may be 20 ms.

[0144] In some embodiments, the determining the difference between one of the determined instantaneous operational parameter values and the determined rolling average value may comprise determining the difference between the most recently determined instantaneous operational parameter value and the rolling average value.

[0145] In other words, the difference between an instantaneous operational parameter value of the heating element and the determined rolling average may be monitored and updated with each consecutive determination of the successive instantaneous operational parameter value.

[0146] In some embodiments, determining the rolling average value of the operational parameter values of the heating element may comprise determining an average of a portion of the sequence of instantaneous operational parameter values. Said plurality may comprise a predetermined number of determined instantaneous operational parameter values.

[0147] In some embodiments, the portion of the sequence of instantaneous operational parameter values may be defined by the most recent predetermined number of determined instantaneous operational parameter values.

[0148] In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be 500 or less, 250 or less, 100 or less, 50 or less, or 25 or less. In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be 25 or more, 50 or more, 100 or more, 250 or more, or 500 or more. In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be between 25 and 500, between 25 and 250, between 25 and 100, between 25 and 50, between 50 and 500, between 50 and 250, between 50 and 100, between 100 and 500, or between 100 and 250.

[0149] In a particular example, the most recent predetermined number of determined instantaneous operational parameter values may be between 50 and 100.

[0150] In some examples, the most recent predetermined number of determined instantaneous operational parameter values may be a number of operational parameter values determined over a predetermined rolling average time period. In other words, the predetermined rolling average time period may be a time period over which the rolling average is determined. In some examples, the predetermined rolling average time period may be 5 seconds or less, 2 seconds or less, 1 second or less, or 0.5 seconds or less. Alternatively, in some examples, the predetermined rolling average time period may be 0.5 seconds or more, 1 second or more, 2 seconds or more, or 5 seconds or more. Alternatively, in some examples, the predetermined rolling average time period may be between 0.5 and 5 seconds, between 0.5 and 2 seconds, between 0.5 and 1 seconds, between 1 and 5 seconds, between 1 and 2 seconds, or between 2 and 5 seconds.

[0151] In a particular example, the predetermined rolling average time period may be between 1 and 2 seconds.

[0152] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element to define a potential divider. Determining each of the plurality of instantaneous resistance values may comprise: applying a supply voltage, by the power supply, across the measurement resistor and the heating element for a measurement period; measuring a midpoint voltage between the measurement resistor and the heating element; and determining an instantaneous resistance of the heating element based on the measured midpoint voltage.

[0153] In some embodiments, determining the instantaneous resistance may comprise comparing the midpoint voltage to the supply voltage to determine the instantaneous resistance.

[0154] In some embodiments, determining the instantaneous resistance may comprise equating the ratio of the instantaneous resistance to a combined resistance with the ratio of the midpoint voltage to the supply voltage. The combined resistance may be a sum of the predetermined resistance of the measurement resistor and the instantaneous resistance of the heating element.

[0155] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element. Determining each of the plurality of instantaneous resistance values may comprise: supplying, by the power supply, a current through the measurement resistor and the heating element; measuring the current passing through the measurement resistor; and determining an instantaneous resistance of the heating element based on the measured current.

[0156] In some embodiments, determining the instantaneous resistance may comprise determining an instantaneous power consumption of the heating element based on a supply voltage of the power supply and the measured current, and determining the instantaneous resistance based on the instantaneous power consumption.

[0157] In some embodiments, the predetermined resistance of the measurement resistor may be less than a nominal resistance of the heating element.

[0158] In other words, determining the instantaneous resistance may comprise applying any of the methods described herein in relation to any other aspects of the present disclosure. For example, any of the methods described herein in relation to operating a measurement resistor in a potential-divider configuration, and / or operating a resistor in a configuration for measuring current passing therethrough may be applied to determine the instantaneous resistance.

[0159] In an aspect, there is provided a method of operating a heat-not-burn, HNB, aerosol-generating apparatus. The HNB aerosol-generating apparatus comprises a heating element and a power supply for supplying power to the heating element. The method comprises: monitoring a resistance of the heating element during operation of the HNB aerosol-generating apparatus; determining a rate of change of the resistance of the heating element over time based on the monitoring of the resistance of the heating element; comparing the determined rate of change to a threshold; and determining a property of a consumable of the aerosol-generating apparatus based on whether or note the determined rate of change exceeds the threshold.

[0160] In some examples, the threshold may be a final threshold. If the determined rate of change exceeds the final threshold, the method further comprises: determining that a consumable is not installed in the aerosol-generating apparatus; and if the determined rate of change does not exceed the final threshold, determining that a consumable is installed in the aerosol-generating apparatus.

[0161] In this way, it may be possible to infer the presence of absence of a consumable in a HNB aerosol-generating apparatus by using pre-existing circuitry (e.g., implemented for use with any of the other methods described herein).

[0162] In some examples, the determined rate of change may be monitored (e.g., continuously monitored) and the comparison of the determined rate of change with the final threshold may be repeated (or iterated) at a predetermined comparison interval.

[0163] In some examples, the comparison interval may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the comparison interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the comparison interval may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0164] In a particular example, the comparison interval may be 20 ms.

[0165] In some embodiments, monitoring the resistance of the heating element may comprise consecutively determining an instantaneous resistance value of the heating element to form a sequence of instantaneous resistance values.

[0166] In some embodiments, each of the sequence of instantaneous resistance values may be determined at a predetermined interval.

[0167] In other words, a determination of a successive instantaneous resistance values may be carried out at the end of each predetermined interval - i.e., a time of length equal to the predetermined interval may pass between each consecutive determination of successive instantaneous resistances.

[0168] In some examples, the predetermined interval may be 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the predetermined interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the predetermined interval may be between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0169] In a particular example, the predetermined interval may be 20 ms.

[0170] In some examples, the predetermined interval and the comparison interval may be the same.

[0171] In some examples, that comparison interval maybe a multiple of the predetermined interval.

[0172] In some embodiments, determining the rate of change of the resistance of the heating element may comprise determining a gradient in the sequence of instantaneous resistance values over time.

[0173] Determining the gradient may, for example, involve determining a numerical differentiation of the sequence of instantaneous resistance values over time (i.e., dR / dt).

[0174] In some embodiments, the method may further comprise, in response to determining that a consumable is not installed in the aerosol-generating apparatus, deactivating the aerosol-generating apparatus.

[0175] When implemented with other methods of those described herein, a power level delivered to the heating element may be boosted upon initialisation of the aerosol-generating apparatus so as to ensure the temperature of the consumable reaches an aerosolization temperature (i.e., a temperature sufficient to generate aerosol) more quickly than is achievable by applying a constant power level. However, if there is no consumable installed in the aerosol-generating apparatus, delivering high power to the heating element risks damaging components of the aerosol generating apparatus and may present a safety risk to users of the apparatus.

[0176] As such, by deactivating the aerosol-generating apparatus, a fail-safe is provided that reduces (or event eliminates) both the damage risk and the safety risk.

[0177] In some embodiments, the threshold may be one of a plurality of thresholds that comprise one or more intermediate thresholds. The method may further comprise: comparing the determined rate of change to each of the one or more intermediate thresholds. For each of the one or more intermediate thresholds, if the determined rate of change of the resistance of the heating element exceeds said threshold, the method may further comprise determining that the mass of the consumable installed in the aerosol-generating apparatus is no more than a corresponding threshold mass. For each of the one or more intermediate thresholds, if the determined rate of change of the resistance of the heating element does not exceed said threshold, the method may further comprise determining that the mass of the consumable installed in the aerosol-generating apparatus is more than the corresponding threshold mass.

[0178] In this way, it may be possible to infer the mass of the consumable installed in the aerosol-generating apparatus by using pre-existing circuity (e.g., implemented for use with any of the other methods described herein).

[0179] In some examples, the comparison of the determined rate of change with each of one or more intermediate thresholds may be repeated (or iterated) at a predetermined intermediate comparison interval.

[0180] In some examples, the intermediate comparison interval maybe 100 ms or less, 50 ms or less, 30 ms or less, 20 ms or less, or 10 ms or less. Alternatively, the intermediate comparison interval may be 5 ms or more, 10 ms or more, 20 ms or more, 30 ms or more, or 50 ms or more. Alternatively, the comparison intermediate comparison interval maybe between 5 and 100 ms, 5 and 50 ms, 5 and 30 ms, 5 and 20 ms, 5 and 10 ms, 10 and 100 ms, 10 and 50 ms, 10 and 30 ms, 10 and 20 ms, 20 and 100 ms, 20 and 50 ms, 20 and 30 ms, 30 and 100 ms, 30 and 50 ms, or 50 and 100 ms.

[0181] In a particular example, the intermediate comparison interval may be 20 ms.

[0182] In some examples, the comparison interval and the intermediate comparison interval may be the same.

[0183] In some examples the Intermediate comparison interval and the predetermined interval may be the same.

[0184] In some examples, all of the intermediate comparison interval, the comparison interval, and the predetermined interval may be the same.

[0185] In some examples, the intermediate comparison interval may be a multiple of the comparison interval.

[0186] In some examples, the intermediate comparison interval may be a multiple of the predetermined interval.

[0187] In some embodiments, the method may further comprise: selecting a power level from amongst one or more predetermined power levels, each corresponding to one of the one or more intermediate thresholds. The selected power level may be selected as the power level corresponding to the lowest intermediate threshold exceeded by the determined rate of change of resistance. The method may further comprise adjusting a power input delivered to the heating element to the selected power level.

[0188] In this way, a power level delivered to heating element may be adjusted in accordance with

[0189] In some embodiments, the power of each of the one or more predetermined power levels is inversely proportional to the corresponding one or more intermediate thresholds.

[0190] Power required to deliver a consistent user experience to a user of the aerosol generating operators may be inversely proportional to a mass of the consumable or stick used to generate aerosol. Therefore, by delivering a power that is inversely proportional to the corresponding intermediate threshold of the one or more intermediate thresholds a more consistent user experience may be ensured for the user of the aerosol generating apparatus.

[0191] In some embodiments, at least one of the one or more intermediate thresholds may be a refill threshold. The method may further comprise: in response to determining that the determined rate of change of the resistance of the heating element exceeds the refill threshold, alerting a user of the aerosol-generating apparatus that the mass of the consumable installed in the aerosol-generating apparatus has fallen below a mass-refill threshold.

[0192] The mass-refill threshold may be a threshold indicative that a refill is needed now or in the near future to ensure that the user can continue to use their aerosol generating apparatus.

[0193] In some examples, alerting the user of the aerosol generating apparatus may involve using any suitable mechanism via any suitable component of the aerosol generating apparatus. For example alerting the user may involve presenting the user with a visual indicator (e.g., a light or LED, such as an orange light or LED that may or may not be flashing). Additionally or alternatively, alerting the user may involve presenting the user with an audible indicator (e.g., an alarm, ping, buzz or any other suitable sound via a speaker of the aerosol-generating apparatus). Personally or alternatively, alerting the user may involve presenting the user with a haptic indicator (e.g., a vibration of the aerosol-generating apparatus, or at least a part of the aerosol-generating apparatus).

[0194] In some embodiments, the method may further comprise, in response to determining that a consumable is not installed in the aerosol-generating apparatus, alerting a user of the aerosol-generating apparatus that a consumable is not installed in the aerosol-generating apparatus.

[0195] In some examples, alerting the user of the aerosol generating apparatus may involve using any suitable mechanism via any suitable component of the aerosol generating apparatus. For example alerting the user may involve presenting the user with a visual indicator (e.g., a light or LED, such as an red light or LED that may or may not be flashing). Additionally or alternatively, alerting the user may involve presenting the user with an audible indicator (e.g., an alarm, ping, buzz or any other suitable sound via a speaker of the aerosol-generating apparatus). Personally or alternatively, alerting the user may involve presenting the user with a haptic indicator (e.g., a vibration of the aerosol-generating apparatus, or at least a part of the aerosol-generating apparatus).

[0196] In some embodiments, the method may further comprise, in response to determining that a consumable is installed in the aerosol-generating apparatus, presenting a user of the aerosol-generating apparatus with an indication that the aerosol-generating apparatus is ready for use.

[0197] In some examples the indication maybe a visual indicator (e.g., a light or a LED such as a green light or a LED that may or may not be flashing). Additionally or alternatively the indication maybe an audible indicator (e.g., an alarm, ping, buzz or any other suitable sound via a speaker of the aerosol generating apparatus). Additionally or alternatively. The indication maybe a haptic indicator (e.g. a vibration of the aerosol generating apparatus or at least a part of the aerosol generating apparatus).

[0198] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element to define a potential divider. Determining each of the sequence of instantaneous resistance values may comprise: applying a supply voltage, by the power supply, across the measurement resistor and the heating element for a measurement period; measuring a midpoint voltage between the measurement resistor and the heating element; and determining an instantaneous resistance of the heating element based on the measured midpoint voltage.

[0199] In some embodiments, the HNB aerosol-generating apparatus may further comprise a measurement resistor having a predetermined resistance electrically connected in series with the heating element. Determining each of the sequence of instantaneous resistance values may comprise: supplying, by the power supply, a current through the measurement resistor and the heating element; measuring the current passing through the measurement resistor; and determining an instantaneous resistance of the heating element based on the measured current.

[0200] In other words, determining the instantaneous resistance may comprise applying any of the methods described herein in relation to any other aspects of the present disclosure. For example, any of the methods described herein in relation to operating a measurement resistor in a potential-divider configuration, and / or operating a resistor in a configuration for measuring current passing therethrough may be applied to determine the instantaneous resistances.

[0201] In some examples, of any of the aspects described herein, when a user activates a HNB aerosol-generating apparatus, the heating element of the aerosol-generating apparatus may be activated for a predetermined period of time, referred to as a "session length". For example, the session length may be eight minutes or less, six minutes or less, four minutes or less, two minutes or less, or one minute or less. Alternatively, the session length may be one minute or more, two minutes or more, four minutes or more, six minutes or more, or eight minutes or more. Alternatively, the session length may be between one and eight minutes, one and six minutes, one and four minutes, one and two minutes, two and eight minutes, two and six minutes, two and four minutes, four and eight minutes, four and six minutes, or six and eight minutes.

[0202] In embodiments and examples where the mass of the consumable is determined (or at least it is determined whether the mass is greater or less than each of a set of mass thresholds), the methods described herein may further comprise: adjusting a session length of the HNB aerosol-generating apparatus based on the determined mass.

[0203] For example, the session length may be inversely proportional to the determined mass of the consumable. In other words, as the mass of the consumable is depleted, the session length delivered upon activation of the heating element may be reduced to reduce the risk of the consumable being completely depleted during a session. Additionally, application of heat, by the heating element, to a relatively lower-mass consumable may result in the consumable being heated to a target temperature (e.g., a steady-state temperature, and / or a temperature at which aerosol is generated from the consumable) relatively more quickly. As such, the session length needed to deliver the same amount of aerosol to a user of the HNB aerosol-generating apparatus may be shorter than for a relatively higher-mass consumable.

[0204] Additionally or alternatively, in embodiments and examples where a power-boost control is applied to the HNB aerosol-generating apparatus (e.g., in cases where the method of operating the HNB aerosol-generating apparatus includes boosting the power output of a power supply to the heating element of the aerosol-generating apparatus in response to a determination that a difference between an instantaneous resistance of the heating element and a rolling average of the resistance of the heating element exceeds a predetermined threshold), the methods described herein may further comprise: adjusting a session length of the HNB aerosol-generating apparatus based on a determined power output supplied to the heating element over the course of a session.

[0205] For example, in sessions during which a larger number of power boosts have been delivered to the heating element, the session length may be adjusted such that a total power delivered to the heating element over the course of the session does not exceed a predetermined total power threshold. In this way, the amount of aerosol generated across different sessions can be made more consistent by ensuring that the amount of power delivered to the heating element within each session (and, consequently, the amount of aerosol generated in each session) remains constant or approximately constant.

[0206] As an example, the session length may be adjusted such that each session comprises an amount of time at which the heating element is operating at a steady-state temperature (and / or a temperature at which aerosol is generated from the consumable) is the same, or approximately the same, across different sessions.

[0207] In another aspect, there is provided a heat-not-burn, HNB, aerosol-generating apparatus comprising: a heating element configured to heat an aerosol precursor; a power supply configured to supply electrical current to the heating element; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out any of the methods described herein. The heating element is heatable by flowing electrical current therethrough.

[0208] In another aspect there may be provided a computer-readable medium, or a computer program comprising logic and / or instructions that, when executed by a processor of a HNB aerosol-generating apparatus, cause the HNB aerosol-generating apparatus to carry out the methods described herein.

[0209] The present disclosure may provide electrical circuitry and / or a computer program configured to cause an aerosol generating apparatus / system to perform any method or method step disclosed herein. A computer readable medium comprising the computer program is also disclosed.

[0210] The preceding summary is provided for purposes of summarizing some examples to provide a basic understanding of aspects of the subject matter described herein. Accordingly, the above-described features should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Moreover, the above and / or proceeding examples may be combined in any suitable combination to provide further examples, except where such a combination is clearly impermissible or expressly avoided. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following text and the accompanying drawings.BRIEF DESCRIPTION OF THE FIGURES

[0211] Aspects, features and advantages of the present disclosure will become apparent from the following description of examples in reference to the appended drawings in which like numerals denote like elements. Fig. 1 is a block system diagram showing an example aerosol generating apparatus. Fig. 2 is a block system diagram showing an example implementation of the apparatus of Fig. 1, where the aerosol generating apparatus is configured to generate aerosol from a solid precursor. Fig. 3 is a schematic diagram showing an example implementation of the apparatus of Fig. 4. Fig. 4 shows an exemplary circuit for carrying out the methods described herein. Fig. 5 shows a method of operating an aerosol-generating apparatus. Fig. 6 shows an exemplary circuit for carrying out the methods described herein. Fig. 7 shows a method of operating an aerosol-generating apparatus. Fig. 8 shows a method of operating an aerosol-generating apparatus. Fig. 9 shows a method of operating an aerosol-generating apparatus. Fig. 10 shows a method of operating an aerosol-generating apparatus. DETAILED DESCRIPTION OF EMBODIMENTS

[0212] Before describing several examples implementing the present disclosure, it is to be understood that the present disclosure is not limited by specific construction details or process steps set forth in the following description and accompanying drawings. Rather, it will be apparent to those skilled in the art having the benefit of the present disclosure that the systems, apparatuses and / or methods described herein could be embodied differently and / or be practiced or carried out in various alternative ways.

[0213] Unless otherwise defined herein, scientific and technical terms used in connection with the presently disclosed inventive concept(s) shall have the meanings that are commonly understood by those of ordinary skill in the art, and known techniques and procedures may be performed according to conventional methods well known in the art and as described in various general and more specific references that may be cited and discussed in the present specification.

[0214] Any patents, published patent applications, and non-patent publications mentioned in the specification are hereby incorporated by reference in their entirety.

[0215] All examples implementing the present disclosure can be made and executed without undue experimentation in light of the present disclosure. While particular examples have been described, it will be apparent to those of skill in the art that variations may be applied to the systems, apparatus, and / or methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit, and scope of the inventive concept(s). All such similar substitutions and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the inventive concept(s) as defined by the appended claims.

[0216] The use of the term "a" or "an" in the claims and / or the specification may mean "one," as well as "one or more," "at least one," and "one or more than one." As such, the terms "a," "an," and "the," as well as all singular terms, include plural referents unless the context clearly indicates otherwise. Likewise, plural terms shall include the singular unless otherwise required by context.

[0217] The use of the term "or" in the present disclosure (including the claims) is used to mean an inclusive "and / or" unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive. For example, a condition "A or B" is satisfied by any of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

[0218] As used in this specification and claim(s), the words "comprising, "having," "including," or "containing" (and any forms thereof, such as "comprise" and "comprises," "have" and "has," "includes" and "include," or "contains" and "contain," respectively) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0219] Unless otherwise explicitly stated as incompatible, or the physics or otherwise of the embodiments, examples, or claims prevent such a combination, the features of examples disclosed herein, and of the claims, may be integrated together in any suitable arrangement, especially ones where there is a beneficial effect in doing so. This is not limited to only any specified benefit, and instead may arise from an "ex post facto" benefit. This is to say that the combination of features is not limited by the described forms, particularly the form (e.g. numbering) of example(s), embodiment(s), or dependency of claim(s). Moreover, this also applies to the phrase "in one embodiment," "according to an embodiment," and the like, which are merely a stylistic form of wording and are not to be construed as limiting the following features to a separate embodiment to all other instances of the same or similar wording. This is to say, a reference to 'an,' 'one,' or 'some' embodiment(s) may be a reference to any one or more, and / or all embodiments, or combination(s) thereof, disclosed. Also, similarly, the reference to "the" embodiment may not be limited to the immediately preceding embodiment. Further, all references to one or more embodiments or examples are to be construed as non-limiting to the claims.

[0220] The present disclosure may be better understood in view of the following explanations, wherein the terms used that are separated by "or" may be used interchangeably: As used herein, an "aerosol generating apparatus" (or "electronic(e)-cigarette") may be an apparatus configured to deliver an aerosol to a user for inhalation by the user. The apparatus may additionally / alternatively be referred to as a "smoking substitute apparatus", if it is intended to be used instead of a conventional combustible smoking article. As used herein a combustible "smoking article" may refer to a cigarette, cigar, pipe or other article, that produces smoke (an aerosol comprising solid particulates and gas) via heating above the thermal decomposition temperature (typically by combustion and / or pyrolysis). An aerosol generated by the apparatus may comprise an aerosol with particle sizes of 0.2 - 7 microns, or less than 10 microns, or less than 7 microns. This particle size may be achieved by control of one or more of: heater temperature; cooling rate as the vapour condenses to an aerosol; flow properties including turbulence and velocity. The generation of aerosol by the aerosol generating apparatus may be controlled by an input device. The input device may be configured to be user-activated, and may for example include or take the form of an actuator (e.g. actuation button) and / or an airflow sensor.

[0221] Each occurrence of the aerosol generating apparatus being caused to generate aerosol for a period of time (which may be variable) may be referred to as an "activation" of the aerosol generating apparatus. The aerosol generating apparatus may be arranged to allow an amount of aerosol delivered to a user to be varied per activation (as opposed to delivering a fixed dose of aerosol), e.g. by activating an aerosol generating unit of the apparatus for a variable amount of time, e.g. based on the strength / duration of a draw of a user through a flow path of the apparatus (to replicate an effect of smoking a conventional combustible smoking article).

[0222] The aerosol generating apparatus may be portable. As used herein, the term "portable" may refer to the apparatus being for use when held by a user.

[0223] As used herein, an "aerosol generating system" may be a system that includes an aerosol generating apparatus and optionally other circuitry / components associated with the function of the apparatus, e.g., one or more external devices and / or one or more external components (here "external" is intended to mean external to the aerosol generating apparatus). As used herein, an "external device" and "external component" may include one or more of a: a charging device, a mobile device (which may be connected to the aerosol generating apparatus, e.g. via a wireless or wired connection); a networked-based computer (e.g. a remote server); a cloud-based computer; any other server system.

[0224] An example aerosol generating system may be a system for managing an aerosol generating apparatus. Such a system may include, for example, a mobile device, a network server, as well as the aerosol generating apparatus.

[0225] As used herein, an "aerosol" may include a suspension of precursor, including as one or more of: solid particles; liquid droplets; gas. Said suspension may be in a gas including air. An aerosol herein may generally refer to / include a vapour. An aerosol may include one or more components of the precursor.

[0226] As used herein, a "precursor" may include one or more of a: liquid; solid; gel; loose leaf material; other substance. The precursor may be processed by an aerosol generating unit of an aerosol generating apparatus to generate an aerosol. The precursor may include one or more of: an active component; a carrier; a flavouring. The active component may include one or more of nicotine; caffeine; a cannabidiol oil; a non-pharmaceutical formulation, e.g. a formulation which is not for treatment of a disease or physiological malfunction of the human body. The active component may be carried by the carrier, which may be a liquid, including propylene glycol and / or glycerine. The term "flavouring" may refer to a component that provides a taste and / or a smell to the user. The flavouring may include one or more of: Ethylvanillin (vanilla); menthol, Isoamyl acetate (banana oil); or other. The precursor may include a substrate, e.g. reconstituted tobacco to carry one or more of the active component; a carrier; a flavouring.

[0227] As used herein, a "storage portion" may be a portion of the apparatus adapted to store the precursor. It may be implemented as fluid-holding reservoir or carrier for solid material depending on the implementation of the precursor as defined above.

[0228] As used herein, a "flow path" may refer to a path or enclosed passageway through an aerosol generating apparatus, e.g. for delivery of an aerosol to a user. The flow path may be arranged to receive aerosol from an aerosol generating unit. When referring to the flow path, upstream and downstream may be defined in respect of a direction of flow in the flow path, e.g. with an outlet being downstream of an inlet.

[0229] As used herein, a "delivery system" may be a system operative to deliver an aerosol to a user. The delivery system may include a mouthpiece and a flow path.

[0230] As used herein, a "flow" may refer to a flow in a flow path. A flow may include aerosol generated from the precursor. The flow may include air, which may be induced into the flow path via a puff by a user.

[0231] As used herein, a "puff" (or "inhale" or "draw") by a user may refer to expansion of lungs and / or oral cavity of a user to create a pressure reduction that induces flow through the flow path.

[0232] As used herein, an "aerosol generating unit" may refer to a device configured to generate an aerosol from a precursor. The aerosol generating unit may include a unit to generate a vapour directly from the precursor (e.g. a heating system or other system) or an aerosol directly from the precursor (e.g. an atomiser including an ultrasonic system, a flow expansion system operative to carry droplets of the precursor in the flow without using electrical energy or other system). A plurality of aerosol generating units to generate a plurality of aerosols (for example, from a plurality of different aerosol precursors) may be present in an aerosol generating apparatus.

[0233] As used herein, a "heating system" may refer to an arrangement of at least one heating element, which is operable to aerosolise a precursor once heated. The at least one heating element may be electrically resistive to produce heat from the flow of electrical current therethrough. The at least one heating element may be arranged as a susceptor to produce heat when penetrated by an alternating magnetic field. The heating system may be configured to heat a precursor to below 300 or 350 degrees C, including without combustion.

[0234] As used herein, a "consumable" may refer to a unit that includes a precursor. The consumable may include an aerosol generating unit, e.g. it may be arranged as a cartomizer. The consumable may include a mouthpiece. The consumable may include an information carrying medium. With liquid or gel implementations of the precursor, e.g. an e-liquid, the consumable may be referred to as a "capsule" or a "pod" or an "e-liquid consumable". The capsule / pod may include a storage portion, e.g. a reservoir or tank, for storage of the precursor. With solid material implementations of the precursor, e.g. tobacco or reconstituted tobacco formulation, the consumable may be referred to as a "stick" or "package" or "heat-not-burn consumable". In a heat-not-burn consumable, the mouthpiece may be implemented as a filter and the consumable may be arranged to carry the precursor. The consumable may be implemented as a dosage or pre-portioned amount of material, including a loose-leaf product.

[0235] As used herein, an "information carrying medium" may include one or more arrangements for storage of information on any suitable medium. Examples include: a computer readable medium; a Radio Frequency Identification (RFID) transponder; codes encoding information, such as optical (e.g. a bar code or QR code) or mechanically read codes (e.g. a configuration of the absence or presents of cut-outs to encode a bit, through which pins or a reader may be inserted).

[0236] As used herein "heat-not-burn" (or "HNB" or "heated precursor") may refer to the heating of a precursor, typically tobacco, without combustion, or without substantial combustion (i.e. localised combustion may be experienced of limited portions of the precursor, including of less than 5% of the total volume).

[0237] As used herein, "electrical circuitry" may refer to one or more electrical components, examples of which may include: an Application Specific Integrated Circuit (ASIC); electronic / electrical componentry (which may include combinations of transistors, resistors, capacitors, inductors etc); one or more processors; a non-transitory memory (e.g. implemented by one or more memory devices), that may store one or more software or firmware programs; a combinational logic circuit; interconnection of the aforesaid. The electrical circuitry may be located entirely at the apparatus, or distributed between the apparatus and / or on one or more external devices in communication with the apparatus, e.g. as part of a system

[0238] As used herein, a "processing resource" (or "processor" or "controller") may refer to one or more units for processing data, examples of which may include an ASIC, microcontroller, FPGA, microprocessor, digital signal processor (DSP) capability, state machine or other suitable component.

[0239] A processing resource may be configured to execute a computer program, e.g. which may take the form of machine readable instructions, which may be stored on a non-transitory memory and / or programmable logic. The processing resource may have various arrangements corresponding to those discussed for the circuitry, e.g. on-board and / or off board the apparatus as part of the system. As used herein, any machine executable instructions, or computer readable media, may be configured to cause a disclosed method to be carried out, e.g. by a aerosol generating apparatus or system as disclosed herein, and may therefore be used synonymously with the term method.

[0240] As used herein, an "external device" (or "peripheral device") may include one or more electronic components external to an aerosol generating apparatus. Those components may be arranged at the same location as the aerosol generating apparatus or remote from the apparatus. An external device may comprise electronic computer devices including: a smartphone; a PDA; a video game controller; a tablet; a laptop; or other like device.

[0241] As used herein, a "computer readable medium / media" (or "memory" or "data storage") may include any medium capable of storing a computer program, and may take the form of any conventional non-transitory memory, for example one or more of: random access memory (RAM); a CD; a hard drive; a solid state drive; a memory card; a DVD. The memory may have various arrangements corresponding to those discussed for the circuitry / processor. The present disclosure includes a computer readable medium configured to cause an apparatus or system disclosed herein to perform a method as disclosed herein.

[0242] It will be appreciated that any of the disclosed methods (or corresponding apparatuses, programs, data carriers, etc.) may be carried out by either a host or client, depending on the specific implementation (i.e. the disclosed methods / apparatuses are a form of communication(s), and as such, may be carried out from either 'point of view', i.e. in corresponding to each other fashion). Furthermore, it will be understood that the terms "receiving" and "transmitting" encompass "inputting" and "outputting" and are not limited to an RF context of transmitting and receiving electromagnetic (e.g. radio) waves. Therefore, for example, a chip or other device or component for realizing embodiments could generate data for output to another chip, device or component, or have as an input data from another chip, device, or component, and such an output or input could be referred to as "transmit" and "receive" including gerund forms, that is, "transmitting" and "receiving," as well as such "transmitting" and "receiving" within an RF context.

[0243] Referring to Fig. 1, an example aerosol generating apparatus 1 includes a power supply 2, for supply of electrical energy. The apparatus 1 includes an aerosol generating unit 4 that is driven by the power supply 2. The power supply 2 may include an electric power supply in the form of a battery and / or an electrical connection to an external power supply. The apparatus 1 includes a precursor 6, which in use is aerosolised by the aerosol generating unit 4 to generate an aerosol. The apparatus 2 includes a delivery system 8 for delivery of the aerosol to a user.

[0244] Electrical circuitry (not shown in figure 1) may be implemented to control the interoperability of the power supply 4 and aerosol generating unit 6.

[0245] In variant examples, which are not illustrated, the power supply 2 may be omitted since, e.g. an aerosol generating unit implemented as an atomiser with flow expansion may not require a power supply.

[0246] Fig. 2 shows an implementation of the apparatus 1 of Fig. 1, where the aerosol generating apparatus 1 is configured to generate aerosol by a-heat not-burn process.

[0247] In this example, the apparatus 1 includes a device body 50 and a consumable 70.

[0248] In this example, the body 50 includes the power supply 4 and a heating system 52. The heating system 54 includes at least one heating element 54. The body may additionally include any one or more of electrical circuitry 56, a memory 58, a wireless interface 60, one or more other components 62.

[0249] The electrical circuitry 56 may include a processing resource for controlling one or more operations of the body 50, e.g. based on instructions stored in the memory 58.

[0250] The wireless interface 60 may be configured to communicate wirelessly with an external (e.g. mobile) device, e.g. via Bluetooth.

[0251] The other component(s) 62 may include an actuator, one or more user interface devices configured to convey information to a user and / or a charging port, for example (see e.g. Fig. 3).

[0252] The body 50 is configured to engage with the consumable 70 such that the at least one heating element 54 of the heating system 52 penetrates into the solid precursor 6 of the consumable. In use, a user may activate the aerosol generating apparatus 1 to cause the heating system 52 of the body 50 to cause the at least one heating element 54 to heat the solid precursor 6 of the consumable (without combusting it) by conductive heat transfer, to generate an aerosol which is inhaled by the user.

[0253] Fig. 3 shows an example implementation of the aerosol generating device 1 of Fig. 2.

[0254] As depicted in Fig. 3, the consumable 70 is implemented as a stick, which is engaged with the body 50 by inserting the stick into an aperture at a top end 53 of the body 50, which causes the at least one heating element 54 of the heating system 52 to penetrate into the solid precursor 6.

[0255] The consumable 70 includes the solid precursor 6 proximal to the body 50, and a filter distal to the body 50. The filter serves as the mouthpiece of the consumable 70 and thus the apparatus 1 as a whole. The solid precursor 6 may be a reconstituted tobacco formulation.

[0256] In this example, the at least one heating element 54 is a rod-shaped element with a circular transverse profile. Other heating element shapes are possible, e.g., the at least one heating element may be blade-shaped (with a rectangular transverse profile) or tube-shaped (e.g. with a hollow transverse profile).

[0257] In this example, the body 50 includes a cap 51. In use the cap 51 is engaged at a top end 53 of the body 50. Although not apparent from Fig. 3, the cap 51 is moveable relative to the body 50. In particular, the cap 51 is slidable and can slide along a longitudinal axis of the body 50.

[0258] The body 50 also includes an actuator 55 on an outer surface of the body 50. In this example, the actuator 55 has the form of a button.

[0259] The body 50 also includes a user interface device configured to convey information to a user. Here, the user interface device is implemented as a plurality of lights 57, which may e.g., be configured to illuminate when the apparatus 1 is activated and / or to indicate a charging state of the power supply 4. Other user interface devices are possible, e.g., to convey information haptically or audibly to a user.

[0260] The body may also include an airflow sensor which detects airflow in the aerosol generating apparatus 1 (e.g., caused by a user inhaling through the consumable 70). This may be used to count puffs, for example.

[0261] In this example, the consumable 70 includes a flow path which transmits aerosol generated by the at least one heating element 54 to the mouthpiece of the consumable.

[0262] In this example, the aerosol generating unit 4 is provided by the above-described heating system 52 and the delivery system 8 is provided by the above-described flow path and mouthpiece of the consumable 70.

[0263] Fig. 4 shows an exemplary circuit 100 for carrying out the methods described herein.

[0264] The circuit 100 comprises a power supply 102 configured to supply a voltage, V BAT , to the circuit 100. The power supply 102 may, for example, be a battery (e.g., a rechargeable battery) arranged and configured to supply power to electrical components of the aerosol-generating apparatus 1.

[0265] The circuit 100 further comprises first and second switches 104, 106 arranged and configured to switchably connect the power supply 102 to and disconnect the power supply 102 from first and second circuit paths respectively.

[0266] The first and / or second switches 104, 106 may be implemented using field-effect transistor (FET) switches. The first and / or second switches 104, 106 may be implemented as P-channel FET switches.

[0267] The first switch 104 is arranged and configured to switchably connect the first circuit path and the power source 102. The first circuit path comprises a measurement resistor 108 having a predetermined resistance. The measurement resistor 108 is arranged in the first circuit path to define a portion of a potential divider. The first circuit path further comprises a voltage-measurement device 110 for measuring the voltage drop across the resistor 108 when the resistor 108 is supplied voltage from the power source 102. The voltage drop may be measured as a difference between the voltage supply by the power source 102, and a remaining voltage after the measurement resistor 108 - in other words, the voltage-measurement device 110 may be configured to measure a midpoint voltage of the first circuit path relative to the voltage supplied by the power source 102. Alternatively, the voltage-measurement device 110 may be configured to measure the amount of voltage remaining after the voltage drop across the resistor 110 - in other words, the voltage-measurement device 110 may be configured to measure a midpoint voltage of the first circuit path relative to electrical ground 116.

[0268] The voltage-measurement device 110 may be implemented using any appropriate means for measuring the voltage drop across the resistor 108. For example, the voltage-measurement device 110 may be implemented as a voltmeter and / or an analog-to-digital converter and / or any other suitable device or apparatus for measuring the voltage drop across the resistor 108.

[0269] The second switch 106 is arranged and configured to switchably connect the second circuit path and the power source 102. The second circuit path bypasses the resistor 108. The power source 102 is connectable to a heating element 122 via the first and / or second circuit paths. The heating element 122 may be a resistive heating element, for example a heater configured to generate heat resisistively in response to current passing therethrough.

[0270] The resistor 108 and the heating element 112 may have similar nominal resistances, as described above. For example, the resistor 108 may have a resistance of 1.6 Ω. The heating element 112 may have a nominal resistance of 1.1 ± 0.1 Ω.

[0271] The circuit 100 may further comprise a third switch 114 arranged and configured to switchably connect the heating element 112 to and disconnect the heating element 112 from electrical ground 116. The third switch 114 may be a FET switch. The third switch 114 may be implemented as a N-channel FET switch. The third switch 114, in this way, may provide a failsafe mechanism to prevent the heating element 112 from failing to respond to a control signal so as to avoid the heating element 112 failing into an ON configuration.

[0272] Fig. 5 shows a method of operating an aerosol-generating apparatus 1 comprising the circuit 100 of Fig. 4.

[0273] The method comprises, by an operation 202, applying a voltage - by power source 102 - across the heating element 112. On initialisation, the first switch 104 may be open and the second switch 106 may be closed such that the measurement resistor 108 is bypassed and voltage is only applied across the heating element 112. Alternatively, on initialisation the first switch 104 may be closed and the second switch 106 may be open such that the measurement resistor 108 is connected in series with the power source 102 and the heating element 112.

[0274] The method further comprises, by an operation 204, waiting for a settling time to elapse to ensure that the voltage being applied across the heating element 112 has a voltage-under-load value (that is typically lower than an initial voltage applicable by the power source 102 in the absence of a resistive load).

[0275] The settling time may, for example, be between 2 and 7 ms. For example, the settling time may be 5 ms.

[0276] The method further comprises, by an operation 206, in response to determining that the settling time has elapsed, switchably connecting the power supply 102 to the heating element 112 through the measurement resistor 108. For example, the operation 206 may comprise closing the first switch 104 and opening the second switch 106 such that the voltage is applied across the first circuit path of the circuit 100. However, as the skilled person will appreciate, in examples where the measurement resistor 108 is already connected in series with the power source 102 and the heating element 112, no action (e.g., no opening or closing of either the first or second switches 104, 106).

[0277] The method further comprises, by an operation 208, applying the supply voltage, V BAT , across the measurement resistor 108 and the heating element 112.

[0278] The method further comprises, by an operation 210, measuring a midpoint voltage between the measurement resistor 108 and the heating element 112. The midpoint voltage may be measured by the voltage-measurement device 110. The midpoint voltage may be indicative of the voltage drop across the measurement resistor 108.

[0279] In this way, the measurement resistor 108 and heating element 112 may be considered to be arranged in the configuration of a potential divider. Measuring the midpoint voltage (i.e., the voltage drop across the resistor 108), therefore enables a determination of an instantaneous resistance of the heating element 112.

[0280] The method further comprises, by an operation 212, connecting the power supply 102 to the heating element 112, bypassing the measurement resistor 108. For example, in the example shown in Fig. 4, the operation 212 comprises opening the first switch 104 and closing the second switch 106 such that the voltage is applied across the second circuit path of the circuit 100.

[0281] The method further comprises, by an operation 214, determining an instantaneous power consumption of the heating element 112. Determining the instantaneous power consumption of the heating element 112 may involve applying Ohm's power law (in the form of P = V 2< / R) to determine the instantaneous power consumption based on the supply voltage applied by the power source 102 and the determined instantaneous resistance of the heating element 112.

[0282] The method further comprises, by an operation 216, selecting an operational mode of the HNB aerosol-generating apparatus 1. The operational mode may, for example, be selected by the user providing user input via the system 80 of Fig. 4. Additionally or alternatively, the HNB aerosol-generating apparatus 1 may comprise a processor configured to select an operational mode of the apparatus 1, for example, in response to detecting and / or identifying the insertion / installation of a particular consumable 70 comprising a particular precursor 6.

[0283] Operational modes of the HNB aerosol-generating apparatus 1 may, for example, be selected to cause the heating element 112 to heat to a particular temperature suitable for heating and aerosolising a particular precursor 6.

[0284] The method further comprises, by an operation 218, determining an ON proportion of a time period for which the heating element 112 needs to be activated to achieve a target average power consumption. The target average power consumption may be a target corresponding to the operational mode selected in operation 216. For example, if the instantaneous power consumption of the heating element 112 is double the target average power consumption, then the ON proportion of the predetermined time period may be determined to be half the time period.

[0285] The method further comprises, by an operation 220, determining whether the ON proportion of the time period has elapsed.

[0286] Once the ON proportion of the time period has elapsed, the method further comprises, by an operation 222, in response to the ON proportion elapsing, disconnecting the power supply 102 such that the supply voltage is no longer applied across the heating element 112.

[0287] Stopping the application of the supply voltage may involve switchably disconnecting the power source 102 from electrical ground 116 by, e.g., opening the third switch 114 and / or the second switch 106.

[0288] One or more of the operations (for example operations 206 to 222 inclusive) may be repeated on a cyclical basis for the duration of the operation of the HNB aerosol-generating apparatus. For example, the full time period over which the method may be carried out may be 20 ms.

[0289] This time period, and the associated method may be repeated on a cyclical basis for the full duration of a user session of the apparatus 1. A user session may be a continuous or substantially continuous period of time during which a user is using the apparatus 1 to draw on generated aerosol. A typical user session may, for example, last between 1 and 10 minutes, e.g., 5 minutes.

[0290] Fig. 6 shows an exemplary circuit 300 for carrying out the methods described herein.

[0291] The circuit 300 comprises a power supply 302 configured to supply a voltage, V BAT , (and a corresponding current) to the circuit 300. The power supply 302 may, for example, be a battery (e.g., a rechargeable battery) arranged and configured to supply power to electrical components of the aerosol-generating apparatus 1.

[0292] The circuit 300 further comprises a first switch 304 arranged and configured to switchably connect the power supply 102 to and disconnect the power supply 102 from the rest of the circuit 300.

[0293] The first switch 304 may be implemented using a FET switch. The first switch 304 may be implemented as a P-channel FET switch.

[0294] The circuit 300 further comprises a measurement resistor 306 having a predetermined resistance. The measurement resistor 306 is arranged with a resistance much lower than a nominal resistance of a heating element 312 of the apparatus 1 (as described above), such that approximately or substantially all of the voltage supplied by the power source 102 is dropped across the heating element 312 and not the measurement resistor 306.

[0295] The circuit 300 further comprises one or more current-measurement devices 308, 310 arranged and configured to measure a current flowing through the measurement resistor 306. The one or more current-measurement device 308 may comprise a current-sense amplifier 308 and a voltage-measurement device 310 configured to measure a voltage output of the current-sense amplifier to infer the value of the current flowing through the measurement resistor 306. The voltage-measurement device 310 may be implemented using any appropriate means for measuring the voltage drop associated with the current-sense amplifier 310. For example, the voltage-measurement device 310 may be implemented as a voltmeter and / or an analog-to-digital converter and / or any other suitable device or apparatus for measuring the voltage drop associated with the current-sense amplifier 308.

[0296] Alternatively, the one or more current-measurement device 308, 310 may be any suitable device or apparatus (or combination thereof) for measuring the current flowing through the measurement resistor 306 (e.g., an ammeter).

[0297] The circuit 300 further comprises a heating element 312. The heating element may be a resistive heating element, for example a heater configured to generate heat resistively in response to current passing therethrough.

[0298] The circuit 300 may further comprise a second switch 314 arranged and configured to switchably connect the heating element 312 to and disconnect the heating element 312 from electrical ground 316. The second switch 314 may be a FET switch. The second switch 314 may be implemented as a N-channel FET switch.

[0299] Fig. 7 shows a method of operating an aerosol-generating apparatus 1 comprising the circuit 300 of Fig. 6.

[0300] The method comprises, by an operation 402, applying a current - by power source 302 -through the measurement resistor 306 and heating element 312. On initialisation, the first switch 304 and second switch 314 may both be closed to facilitate the flow of current through the circuit 300.

[0301] The method further comprises, by an operation 404, waiting for a settling time to elapse to ensure that the current being supplied through the circuit 300 has a current-under-load value (that is typically lower than an initial current applicable by the power source 302 in the absence of a resistive load).

[0302] The settling time may, for example, be between 2 and 7 ms. For example, the settling time may be 5 ms.

[0303] The method further comprises, by an operation 406, in response to determining that the settling time has elapsed, measuring the current flowing through the measurement resistor 306, for example using the current-sense amplifier 308 and voltage measuring device 310 shown in Fig. 7.

[0304] The method further comprises, by an operation 408, determining an instantaneous power consumption of the heating element 312. Determining the instantaneous power consumption of the heating element 312 may involve applying Ohm's power law (P = IV) to determine the instantaneous power consumption based on the supply voltage, V BAT , by the power source 302 and the determined current flowing through the resistor 306.

[0305] The method further comprises, by an operation 410, selecting an operational mode of the HNB aerosol-generating apparatus 1. The operational mode may, for example, be selected by the user providing user input via the system 80 of Fig. 4. Additionally or alternatively, the HNB aerosol-generating apparatus 1 may comprise a processor configured to select an operational mode of the apparatus 1, for example, in response to detecting and / or identifying the insertion / installation of a particular consumable 70 comprising a particular precursor 6.

[0306] Operational modes of the HNB aerosol-generating apparatus 1 may, for example, be selected to cause the heating element 112 to heat to a particular temperature suitable for heating and aerosolising a particular precursor 6.

[0307] The method further comprises, by an operation 412, determining an ON proportion of a time period for which the heating element 312 needs to be activated to achieve a target average power consumption. The target average power consumption may be a target corresponding to the operational mode selected in operation 410. For example, if the instantaneous power consumption of the heating element 312 is double the target average power consumption, then the ON proportion of the predetermined time period may be determined to be half the time period.

[0308] The method further comprises, by an operation 414, determining whether the ON proportion of the time period has elapsed.

[0309] Once the ON proportion of the time period has elapsed, the method further comprises, by an operation 416, in response to the ON proportion elapsing, disconnecting the power supply 302 such that the current is no longer applied through the heating element 312.

[0310] Stopping the application of the supply voltage may involve switchably disconnecting the power source 302 from electrical ground 316 by, e.g., opening the first switch 304 and / or the second switch 314.

[0311] One or more of the operations (for example operations 406 to 416 inclusive) may be repeated on a cyclical basis for the duration of the operation of the HNB aerosol-generating apparatus. For example, the full time period over which the method may be carried out may be 20 ms.

[0312] This time period, and the associated method may be repeated on a cyclical basis for the full duration of a user session of the apparatus 1. A user session may be a continuous or substantially continuous period of time during which a user is using the apparatus 1 to draw on generated aerosol. A typical user session may, for example, last between 1 and 10 minutes, e.g., 5 minutes.

[0313] Fig. 8 shows a method of operating an aerosol-generating apparatus 1 having power-boost functionality.

[0314] The method comprises, in an operation 502, monitoring the instantaneous resistance of the heating element 112, 312 by consecutively determining a plurality of instantaneous resistances of the heating element 112, 312 (e.g., at regular predetermined intervals). The determination of each of the instantaneous resistances may be carried out by implementing the same or similar methods set out above in relation to Figs. 5 and 7. For the avoidance of doubt, although Fig. 8 is described herein in relation to the determination of resistance values, the method is equally applicable in the context of monitoring a temperature of the heating element 112, 312 by consecutively determining a plurality of any instantaneous operational parameter values from which a temperature of the heating element 112, 312 may be inferred.

[0315] The method further comprises, in an operation 504, determining a rolling average of the resistance of the heating element 112, 312, for example by determining an average of a subset of the plurality of instantaneous resistances (e.g., the subset of instantaneous resistances determined in the most recent 1 to 2 seconds).

[0316] The method further comprises, in an operation 506, a difference between one of the determined instantaneous resistances (e.g., the most recently determined instantaneous resistance), and the determined rolling average of the resistance of the heating element 112, 312.

[0317] The method further comprises, in an operation 508, determining whether the determined difference exceeds a predetermined difference threshold. The predetermined difference threshold may be one of a plurality of different predetermined difference thresholds.

[0318] If the determined difference does not exceed the predetermined difference threshold, then the method may cyclically repeat by returning to operation 502 to determine the next of the consecutive instantaneous resistances.

[0319] If the determined difference does exceed the predetermined difference threshold, the method further comprises, in an operation 510, boosting a power output of the power supply 102, 302. This may induce a boosted power consumption by the heating element 112, 312 such that, when the heating element's 112, 312 power consumption drops below a threshold, the power supplied is boosted to return the heating element 112, 312 to standard (or normal) operating parameters more quickly.

[0320] In examples, where the predetermined difference threshold is one of a plurality of different predetermined difference thresholds, the power level to which the power supplied by the power source 102, 302 is boosted may be a preselected boosted power level that is inversely proportional to the magnitude of the corresponding difference threshold.

[0321] Boosting the power supply may involve boosting a power output of the power supply 102, 302 for an extended period of time (e.g., 1-3 seconds) to ensure that the power consumption of the heating element 112, 312 recovers to normal / standard operating levels.

[0322] Fig. 9 shows a method 600 of operating an aerosol-generating apparatus 1 to determine whether a consumable 70 is installed in the apparatus 1 or not.

[0323] The method 600 comprises, in an operation 602, monitoring the resistance of the heating element 112, 312 (e.g., by determining a plurality of instantaneous resistances of the heating element 112, 312 at regular predetermined intervals). The monitoring of the resistance may be carried out by implementing the same or similar methods set out above in relation to Figs. 5 and 7.

[0324] The method 600 further comprises, in an operation 604, determining a rate of change of the resistance of the heating element 112, 312 over time, for example by carrying out a numerical differentiation of the determined instantaneous resistances over time.

[0325] The method 600 further comprises, in an operation 606, comparing the determined rate of change to a final threshold. The final threshold may be individually calibrated for a specific aerosol-generating apparatus 1.

[0326] If the determined rate of change of the resistance of the heating element 112, 312 exceeds the final threshold, the method 600 proceeds to operation 608, in which it is determined that there is no consumable 70 installed in the aerosol-generating apparatus 1.

[0327] If it is determined that there is no consumable 70 installed in the aerosol-generating apparatus 1, the method 600 may further comprise, in an operation 610, alerting a user of the aerosol-generating apparatus 1 that there is no consumable 70 installed therein. The alert may, for example, take the form of an alarm (or other audible alert), a flashing red light (or other visible alert), or a vibration of the aerosol-generating apparatus 1 (or other haptic alert).

[0328] If it is determined that there is no consumable 70 installed in the aerosol-generating apparatus 1, the method 600 may further comprise, in an operation 612, deactivating the aerosol-generating apparatus, thereby reducing (or even eliminating) damage risks and safety risks of heating the heating element 112, 312 with no consumable 70 installed in the aerosol-generating apparatus 1.

[0329] If the determined rate of change of the resistance of the heating element 112, 312 does not exceed the final threshold, the method 600 proceeds to operation 614, in which it is determined that there is a consumable 70 installed in the aerosol-generating apparatus.

[0330] If it is determined that there is a consumable 70 installed in the aerosol-generating apparatus, the method 600 may further comprise, in an operation 616, providing the user with an indication that the consumable 70 is installed in the aerosol-generating apparatus 1. The indication may, for example, take the form of a green light (or other visible indication).

[0331] The method 600 may be repeated (or iterated) to provide a continuous or near-continuous monitoring of the rate of change of resistance of the heating element 112, 312 over time, and to provide a continuous or near-continuous monitoring of whether a consumable 70 is installed in the aerosol-generating apparatus 1 or not.

[0332] Alternatively, the method 600 may be carried out upon activation or initialisation of the aerosol-generating apparatus 1 - e.g., as part of a start-up sequence of the aerosol-generating apparatus 1.

[0333] Fig. 10 shows a method 700 of operating an aerosol-generating apparatus 1 to determine and / or monitor the mass of a consumable 70 installed in the apparatus 1. The method 700 of Fig. 10 may be carried out concurrently with or consecutively to the method 600 of Fig. 9.

[0334] The method 700 comprises, in an operation 702, monitoring the resistance of the heating element 112, 312 (e.g., by determining a plurality of instantaneous resistances of the heating element 112, 312 at regular predetermined intervals). The monitoring of the resistance may be carried out by implementing the same or similar methods set out above in relation to Figs. 5 and 7. Operation 702 may be the same operation as operation 602 of the method 600 in Fig. 9.

[0335] The method 700 further comprises, in an operation 704, determining a rate of change of the resistance of the heating element 112, 312 over time, for example by carrying out a numerical differentiation of the determined instantaneous resistances over time. Operation 704 may be the same operation as operation 604 of the method 600 in Fig. 9.

[0336] The method 700 further comprises, in an operation 706, comparing the determined rate of change to one of one or more intermediate thresholds (e.g., a lowest intermediate threshold of the one or more intermediate thresholds). The one or more intermediate thresholds may be individually calibrated for a specific aerosol-generating apparatus 1.

[0337] If the determined rate of change of the resistance of the heating element 112, 312 exceeds the intermediate threshold under consideration, the method 700 proceeds to operation 708, in which it is determined that the mass of the consumable 70 is less than a corresponding mass threshold.

[0338] The method 700 may further comprise, in an operation 710, determining whether the intermediate threshold under consideration is a refill threshold (e.g., a highest of the one or more intermediate thresholds). The refill threshold may also be referred to equivalently as a depletion threshold (i.e., a threshold indicative that the consumable 70 is depleted).

[0339] If the intermediate threshold under consideration is the refill threshold, the method 700 may further comprise, in an operation 712, alerting a user of the aerosol-generating apparatus 1 that the consumable 70 of the aerosol-generating apparatus 1 is depleted and that the consumable 70 needs to be replaced (either immediately or in the near-future). The alert may, for example, take the form of an alarm (or other audible alert), a flashing orange / amber light (or other visible alert), or a vibration of the aerosol-generating apparatus 1 (or other haptic alert).

[0340] If the intermediate threshold under consideration is not the refill threshold, the method 700 may return to operation 706, comparing the determined rate of change of the resistance of the heating element 112, 312 with a next of the one or more intermediate thresholds (e.g., the next lowest intermediate threshold). In this way, the method 700 may iterate through each of the one or more intermediate thresholds to determine a depletion level of the consumable 70 of the aerosol-generating apparatus 1 (e.g., a mass of the consumable 70 or a range within which the mass of the consumable 70 lies).

[0341] In some examples (such as examples where method 600 depicted in Fig. 9 and the method 700 depicted in Fig. 10 are implemented concurrently in the same aerosol generating apparatus 1), if the intermediate threshold under consideration is the refill threshold, the method 700 may further comprise proceeding to operation 606 of Fig. 9 and comparing the determined rate of change of resistance of the heating element 112, 312 to the final threshold (and subsequently proceeding with the remaining operations of Fig. 6. In this way, A method may be provided that not only informs the user of when the consumable 70 is depleted, but also when the consumable 70 is not even installed in the aerosol generating apparatus 1.

[0342] If the determined rate of change of the resistance of the heating element 112, 312 does not exceed the intermediate threshold under consideration, the method 700 proceeds to operation 714, in which it is determined that the mass of the consumable 70 is more than the corresponding mass threshold.

[0343] The method 700 may further comprise, in an operation 716, providing a user of the aerosol generating apparatus 1 with an indication that the consumable is not depleted. The indication may, for example, take the form of a green light (or other visible indication). The indication may, for example, be the same indication as provided in operation 616 of the method 600 of Fig. 9.

[0344] After completing the iterations of operations 706 to 716 (e.g., after providing the user of the aerosol-generating apparatus with either (i) an alert that the consumable 70 is depleted or (ii) an indication that the consumable 70 is not depleted), the method 700 may proceed to operation 718, in which a power output level is adjusted in accordance with a determined mass (or mass range) of the consumable 70. To achieve this, operation 718 may involve selecting a power level from one or more predetermined power levels, each corresponding to one of the one or more intermediate thresholds. The selected power level, selected in operation 718, is the power level corresponding to the highest of the intermediate thresholds that the determined rate of change of resistance of the heating element 112, 312 exceeds. The power in each of the power levels is inversely proportional to the levels of the corresponding intermediate thresholds -that is, the higher the intermediate threshold, the lower the power output associated with the corresponding power level.

[0345] Upon selection of the selected power level, the aerosol-generating apparatus 1 applies the selected power level as power input to the heating element 112, 312 to induce or maintain aerosolization of the consumable 70 by the heating element 112, 312. By reducing the power input to the heating element 112, 312 as the mass of the consumable 70 is depleted, a more consistent user experience is provided to a user of the aerosol-generating apparatus.

[0346] The method 700 may be repeated (or iterated) to provide a continuous or near-continuous monitoring of the rate of change of resistance of the heating element 112, 312 over time, and to provide a continuous or near-continuous monitoring of the mass of a consumable 70 installed in the aerosol-generating apparatus 1.

[0347] Alternatively, the method 700 may be carried out upon activation or initialisation of the aerosol-generating apparatus 1 - e.g., as part of a start-up sequence of the aerosol-generating apparatus 1.

Examples

Embodiment Construction

[0212]Before describing several examples implementing the present disclosure, it is to be understood that the present disclosure is not limited by specific construction details or process steps set forth in the following description and accompanying drawings. Rather, it will be apparent to those skilled in the art having the benefit of the present disclosure that the systems, apparatuses and / or methods described herein could be embodied differently and / or be practiced or carried out in various alternative ways.

[0213]Unless otherwise defined herein, scientific and technical terms used in connection with the presently disclosed inventive concept(s) shall have the meanings that are commonly understood by those of ordinary skill in the art, and known techniques and procedures may be performed according to conventional methods well known in the art and as described in various general and more specific references that may be cited and discussed in the present specification.

[0214]Any paten...

Claims

1. A method of operating a heat-not-burn, HNB, aerosol-generating apparatus (1), the HNB aerosol-generating apparatus comprising a heating element (112, 312) and a measurement resistor (108, 306) having a predetermined resistance electrically connected in series, wherein the method comprises: applying, by a power supply (102, 302), an electrical signal across the heating element (112, 312) and the measurement resistor (108, 306); determining, based on a measurement of the applied electrical signal, an instantaneous power consumption of the heating element (112, 312); determining, using the instantaneous power consumption of the heating element (112, 312), an ON proportion of a time period, such that, when the heating element is activated for the ON proportion of the time period, a target average power consumption by the heating element over the time period is achieved; and applying the supply voltage, by the power supply (102, 302), across the heating element (112, 312) for the ON proportion of the time period to achieve the target average power consumption.

2. The method according to claim 1, wherein the measurement resistor (108) is electrically connected in series with the heating element (112) to define a potential divider; wherein applying the electrical signal includes: applying a supply voltage, by a power supply (102), across the resistor (108) and the heating element (112) for an initial period; wherein the method further comprises: measuring a midpoint voltage between the resistor (108) and the heating element (112); and wherein the determining the instantaneous power consumption of the heating element (112) is based on the measured midpoint voltage.

3. The method according to claim 2, wherein the measurement resistor (108) and the heating element (112) are arranged such that current flowing from the power supply (102) flows through the measurement resistor (108) before flowing through the heating element (112).

4. The method according to claim 2 or 3, wherein the measurement resistor (108) is switchably connected in series with the heating element (112) such that the supply voltage is not applied across the resistor when applying the supply voltage across the heating element (112) for the determined ON proportion of the time period to achieve the target average power consumption.

5. The method according to any of claims 2 to 4, wherein measuring the midpoint voltage is carried out after a predetermined settling time has elapsed after beginning to apply the supply voltage across the heating element (112).

6. The method according to any of claims 2 to 5, wherein determining the instantaneous power consumption of the heating element (112) comprises: determining a voltage ratio between the supply voltage and the midpoint voltage, wherein the determined voltage ratio is equal to a resistance ratio between the predetermined resistance and an instantaneous resistance of the heating element (112); determining the instantaneous resistance of the heating element (112) using the determined voltage ratio and the predetermined resistance; and determining the instantaneous power consumption of the heating element (112) using the measured midpoint voltage and the determined instantaneous resistance of the heating element (112).

7. The method according to claim 1, wherein applying, the electrical signal includes: supplying, by the power supply (302) a current through the measurement resistor (306) and the heating element (312); wherein the method further comprises: measuring the current passing through the resistor; and wherein the determining the instantaneous power consumption of the heating element (312) is based on the measured current.

8. The method according to claim 7, wherein the predetermined resistance is at least 10 times lower than a nominal resistance of the heating element.

9. The method according to claim 7 or 8, wherein measuring the current passing through the measurement resistor (306) comprises using a current sense amplifier (308) to measure the current.

10. The method according to any of claims 7 to 9, wherein measuring the current is carried out after a predetermined settling time has elapsed after beginning to apply the current through the measurement resistor.

11. The method according to any of claims 7 to 10, wherein determining the instantaneous power consumption of the heating element (312) comprises: estimating a voltage drop across the heating element (312) as being equal to the supply voltage; and determining the instantaneous power consumption of the heating element (312) as the product of the voltage drop and the measured current.

12. The method according to any preceding claim, wherein the method is cyclically repeated during operation of the HNB aerosol generating apparatus (1).

13. The method according to any preceding claim, wherein applying the supply voltage, by the power supply (102), across the heating element (112) for the determined ON proportion of the time period to achieve the target average power consumption involves: applying the supply voltage, by the power supply (102), across the heating element (112) for a first continuous portion of the time period equal to the determined ON proportion; and preventing the supply of the supply voltage for a second, subsequent, continuous portion of the time period equal to the remainder of the time period.

14. The method according to any preceding claim, further comprising: selecting an operation mode of the HNB aerosol-generating apparatus (1) from amongst a plurality of operation modes, wherein each operation mode requires a respective power consumption, and wherein the target average power consumption is the respective power consumption corresponding to the selected operation mode of the HNB aerosol-generating apparatus (1).

15. A heat-not-burn, HNB, aerosol-generating apparatus (1) comprising: a heating element (112) configured to heat an aerosol precursor, wherein the heating element is heatable by flowing electrical current therethrough; a power supply (102) configured to supply electrical current to the heating element; a measurement resistor (108) having a predetermined resistance; and a processor configured to execute logic that causes the aerosol-generating apparatus to carry out the method of any preceding claim.

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