Aerosol-generating system

Abstract

There is provided a method for determining whether insufficient aerosol precursor is present at an aerosol-generating unit of an aerosol-generating system, the method comprising: determining that an aerosol generation session has started at a first point in time (120); generating a driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle (130); monitoring the duty cycle of the driving signal during the aerosol generation session (160); determining that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time (170); comparing a time period between the first point in time and the second point in time to a reference time period (180); and if the time period is less than the reference time period, determining that insufficient aerosol precursor is present at the aerosol-generating unit (190).

Description

FIELD

[0001] The present disclosure relates to systems and methods for determining whether insufficient aerosol precursor is present at an aerosol-generating unit.BACKGROUND

[0002] An electronic vapour product (EVP), also known as a vaping apparatus or a vape, is a type of aerosol-generating system in which an aerosol precursor (e.g. a liquid or gel) is aerosolised by an aerosol-generating unit, such as a heating element or ultrasonic element.

[0003] An aerosol-generating unit may cease to function, or become damaged, if driven in the absence of aerosol precursor at the aerosol-generating unit. The burden of determining whether sufficient aerosol precursor is present in the aerosol-generating unit is typically placed on the user and is often a matter of visual inspection by the user, which can be challenging to perform with any accuracy.

[0004] It is against this background that the present invention has been developed.SUMMARY

[0005] The present disclosure provides a method for determining whether insufficient aerosol precursor is present at an aerosol-generating unit of an aerosol-generating system.

[0006] The method comprises the steps of determining that an aerosol generation session has started at a first point in time and generating a driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle.

[0007] It will be understood that the term duty cycle, which may also be referred to as power cycle or duty factor, refers to the percentage of time that a system or signal is active within a period, the period being the time for a signal to complete a cycle of ON and OFF. For example, for a signal having a period of 1s, a duty cycle of 50% means that the signal includes 0.5s of an ON signal and 0.5s of an OFF signal. For example, for a signal having a period of 2s, a duty cycle of 25% means that the includes 0.5s of an ON signal and 1.5s of an OFF signal. A duty cycle of 100% will mean that the signal is always ON and a duty cycle of 0% will means the signal is always OFF. Duty cycle may be represented either by a percentage or a ratio.

[0008] The duty cycle of the driving signal may be variable. The duty cycle of the driving signal may be controlled using pulse width modulation (PWM). PWM may be used to control the variation of the duty cycle over time.

[0009] The duty cycle of the driving signal may be varied in order to control the average power delivered to the aerosol-generating unit for generating the aerosol. As outlined in further detail below, the behaviour and voltage requirements of the aerosol-generating unit may vary across the aerosol generation session, and so the duty cycle may be varied over the aerosol generation session accordingly.

[0010] In some examples, the method may comprise monitoring the duty cycle of the driving signal during the aerosol generation session. For example, where the duty cycle varies over the aerosol generation session, monitoring the duty cycle of the driving signal may comprise monitoring the variation in the duty cycle of the driving signal over time.

[0011] In some examples, the method may comprise determining that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time. The second point in time may be after the first point in time. In some examples, the predetermined duty cycle threshold may be around 20% or less, for example around 10% or less.

[0012] For example, if the duty cycle of the driving signal is varied in order to control the average power delivered to the aerosol-generating unit, the duty cycle may be reduced over the course of the aerosol generation session. A reduction in the duty cycle of the driving signal, and so a reduction in the power delivered to aerosol-generating unit, may be indicative of a problem with the aerosol-generating unit.

[0013] For example, if insufficient aerosol precursor is present at the aerosol-generating unit, a parameter of the aerosol-generating unit may change to be outside of an acceptable range. In response, the duty cycle of the driving signal may be reduced in order to prevent damage to the aerosol-generating unit, or to prevent an inferior aerosol from being generated by the aerosol-generating unit.

[0014] Insufficient aerosol precursor may be understood to mean an absence or a partial absence, of aerosol precursor at the aerosol-generating unit. For example, in order to generate an acceptable aerosol, the aerosol-generating unit may require a predetermined amount of aerosol precursor. If the amount of aerosol precursor at the aerosol-generating unit is greater than, or equal to, the predetermined amount of aerosol precursor, then it may be considered that sufficient aerosol precursor is present at the aerosol-generating unit. If the amount of aerosol precursor at the aerosol-generating unit is less than the predetermined amount of aerosol precursor, then it may be considered that insufficient aerosol precursor is present at the aerosol-generating unit.

[0015] In some examples, the aerosol precursor may be a liquid or a gel. In such an example, insufficient aerosol precursor being present at the aerosol-generating unit may result in the aerosol-generating unit, or a part of the aerosol-generating unit (such as a wick), being dry.

[0016] In some examples, a time period between the first point in time and the second point in time may be compared to a reference time period. If the time period is less than the reference time period, the method may comprise determining that insufficient aerosol precursor is present at the aerosol-generating unit. In some examples, the reference time period around one second or less, for example around half a second or less.

[0017] For example, an aerosol generation session may comprise at least some variation in the duty cycle of the driving signal. The duty cycle may be varied over the course of the aerosol generation session to account for changes in a parameter of the aerosol-generating unit or for changes in the amount of aerosol precursor present at the aerosol-generating unit.

[0018] However, a rapid reduction in the duty cycle of the driving signal, i.e., the duty cycle falling below the predetermined threshold within the reference time period, may be indicative of a problem with the aerosol-generating unit, such as insufficient aerosol precursor being present at the aerosol-generating unit.

[0019] In other words, there is provided a means of determining that an insufficient amount of aerosol precursor is present at an aerosol-generating unit based on the duty cycle, and in particular based on changes in the duty cycle, of a signal for driving the aerosol-generating unit.

[0020] Put another way, by monitoring the duty cycle of the signal for driving the aerosol-generating unit, it can be determined whether the aerosol-generating unit is functioning correctly, for example is being supplied with sufficient aerosol precursor for aerosol generation.

[0021] Determining that insufficient aerosol precursor is present at the aerosol-generating unit may comprise one or more of: determining that a supply of the aerosol precursor has been exhausted; determining that insufficient time has elapsed between the first point in time and the second point in time and, determining that a supply of the aerosol precursor is impeded from reaching the aerosol-generating unit.

[0022] In some examples, the method further comprises monitoring a parameter of the aerosol-generating unit during the aerosol generation session. In some examples, a plurality of parameters of the aerosol-generating unit may be monitored during the aerosol generation session. The method may further comprise adjusting the duty cycle based on the parameter(s).

[0023] The parameter(s) of the aerosol-generating unit may comprise one or more of: an electrical characteristic of the aerosol-generating unit; and a physical characteristic of the aerosol-generating unit. The electrical characteristic of the aerosol-generating unit may comprise one or more of: a current; a voltage; and a resistance. The physical characteristic of the aerosol-generating unit may comprise a temperature of the aerosol-generating unit.

[0024] In some examples, the aerosol-generating unit comprises a heating system for heating the aerosol precursor to generate an aerosol. The (physical) parameter of the aerosol-generating unit may comprise a temperature of the heating system.

[0025] For example, the temperature of the heating system may be monitored during the aerosol generation session. An aerosol precursor may have an aerosolization temperature at which aerosol is produced. Accordingly, the heating system may be driven to reach and maintain the aerosolization temperature over the course of an aerosol generation session.

[0026] If the heating system is starting from a relatively low temperature, such as ambient temperature, the duty cycle of the driving signal may be initially higher in order to deliver a higher average power to the heating system in order to increase the temperature of the heating system quickly for aerosol production. As the temperature of the heating system approaches the aerosolization temperature, the duty cycle of the driving signal may be decreased in order to slow the rise in temperature so as not to overshoot the aerosolization temperature and burn the aerosol precursor. When the temperature of the heating system has reached the aerosolization temperature, the duty cycle of the driving signal may be brought to a minimum level, for example a duty cycle of around 10%, required to maintain the temperature of the heating system at the aerosolization temperature for the remaining time of the aerosol generation session.

[0027] If the heating system is starting from a relatively high temperature, the duty cycle of the driving signal may be initially lower and decrease more rapidly than for a heating system starting at a lower temperature.

[0028] In the example where the aerosol precursor is a liquid, the amount of liquid aerosol precursor present at the aerosol-generating unit may affect how the temperature of the heating system changes in response to the driving signal.

[0029] For example, an aerosol-generating unit having sufficient aerosol precursor liquid, i.e., an amount of aerosol precursor greater than or equal to a predetermined amount of aerosol precursor liquid, present may require a higher initial duty cycle at the start of an aerosol generation session to bring the temperature of the heating system up to the aerosolization temperature as a portion of the thermal energy may be absorbed by the aerosol precursor liquid. Once again, when the temperature of the heating system has reached the aerosolization temperature, the duty cycle of the driving signal may be reduced to maintain the temperature of the heating system at the aerosolization temperature.

[0030] For example, an aerosol-generating unit having insufficient aerosol precursor liquid, i.e. less than a predetermined amount of aerosol precursor liquid, present may result in the temperature of the heating system reaching the aerosolization temperature more rapidly than when there is sufficient aerosol precursor liquid present at the aerosol-generating unit. Therefore, if insufficient aerosol precursor liquid is present at the aerosol-generating unit, the duty cycle of the driving signal may drop more rapidly towards the maintenance level of the duty cycle, for example 10%.

[0031] Accordingly, for a newly initiated aerosol generation session in which the heating system is at a relatively low temperature, for example after a sufficient period has elapsed since the previous aerosol generation session, a rapid decrease in duty cycle (i.e., the duty cycle falling below the predetermined duty cycle threshold within the predetermined time period) may indicate that the heating system is heating too quickly due to an absence of aerosol precursor liquid, for example rather than due to any latent heat of the heating system itself.

[0032] The determination that insufficient aerosol precursor is present at the aerosol-generating unit may be indicative that the aerosol precursor supply is exhausted or that the aerosol precursor has not had sufficient time to reach, and replenish, the aerosol-generating unit since a previous aerosol generation session.

[0033] In some examples, the method may comprise determining a rate of change of the duty cycle of the driving signal during the aerosol generation session. If the rate of change of the duty cycle exceeds a predetermined rate of change threshold, the method may comprise determining that insufficient aerosol precursor is present at the aerosol-generating unit.

[0034] In the examples outlined above, the method may await the duty cycle falling below the predetermined duty cycle threshold before determining that insufficient aerosol precursor is present at the aerosol-generating unit. In some examples, the method may comprise determining that insufficient aerosol precursor is present at the aerosol-generating unit based on the rate of change of the duty cycle, for example how quickly the duty cycle is decreasing during the aerosol generation session.

[0035] For example, the duty cycle of the driving signal may be around 80% at the start of an aerosol generation session and may decrease over the course of the aerosol generation session towards a maintenance duty cycle, for example of around 10%. As outlined above, if the duty cycle falls below the predetermined duty cycle threshold, for example below around 10%, it may be determined that insufficient aerosol precursor is present at the aerosol-generating unit. Additionally, if the duty cycle falls too rapidly towards the predetermined duty cycle threshold, it may also be determined that insufficient aerosol precursor is present at the aerosol-generating unit. For example, from an initial duty cycle, a rate of change of duty cycle of over 50% per second may exceed a predetermined rate of change threshold.

[0036] In some examples, determining that the aerosol generation session has started may comprise receiving an activation signal for activating the aerosol-generating unit. The method may comprise determining that the aerosol-generating session has started based on the activation signal.

[0037] The activation signal may be any signal for causing the aerosol-generating unit to generate an aerosol. For example, where the aerosol-generating unit comprises a heating system, the activation signal may be a signal for activating the heating system to generate heat for heating the aerosol precursor to form an aerosol. The activation signal may be received from any suitable source for generating an activation signal. For example, the activation signal may be received from a user interface configured to receive a user input and, responsive to the user input, to generate the activation signal. The user interface may comprise a button or switch. The user interface may comprise a pressure sensor for detecting a puff of the user.

[0038] The present disclosure may further provide a method for controlling an aerosol-generating unit of an aerosol-generating system. In some examples, the method may comprise determining that a new aerosol generation session has started. Determining that a new aerosol generation session has started may comprise the same steps as determining that an aerosol generation session has begun at a first point in time outlined above.

[0039] In some examples, the method may comprise obtaining an elapsed time between the new aerosol generation session and a previous aerosol generation session. The previous aerosol generation session may be the aerosol generation session immediately preceding the new aerosol generation session, i.e., there may be no intermediate aerosol generation sessions between the previous aerosol generation session and the new aerosol generation session.

[0040] In some examples, the elapsed time may be compared to a predetermined elapsed time threshold. If the elapsed time is greater than, or equal to, the predetermined elapsed time threshold, the method may comprise determining whether insufficient aerosol precursor is present at the aerosol-generating unit of the aerosol-generating system according to the methods described above. If the elapsed time is less than the predetermined elapsed time threshold, the method may comprise generating an aerosol using the aerosol-generating unit. In some examples, the elapsed time period is greater than around two seconds, for example greater than around three, four or five seconds.

[0041] In some examples, an aerosol generation session may correspond to a single inhalation by a user. Accordingly, if the elapsed time between a new aerosol generation session and a previous aerosol generation session is below a predetermined elapsed time threshold, the user may be performing consecutive inhalations using the aerosol-generating system.

[0042] The present disclosure may further provide an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating unit for generating an aerosol from an aerosol precursor and a controller. In some examples, the aerosol precursor may be a liquid or a gel. The controller may be adapted to perform the method steps outlined above.

[0043] In some examples, the controller may be adapted to determine that an aerosol generation session has started at the first point in time and generate the driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle.

[0044] In some examples, the controller may monitor the duty cycle of the driving signal during the aerosol generation session and determine that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time.

[0045] In some examples, the controller may compare a time period between the first point in time and the second point in time to a reference time period and, if the time period is less than the reference time period, determine that insufficient aerosol precursor is present at the aerosol-generating unit.

[0046] In some examples, the aerosol-generating unit may comprise a heating system. The controller may be adapted to monitor a parameter of the aerosol-generating unit during the aerosol generation session. In some examples, the parameter may comprise a temperature of the heating system. The controller may be adapted to adjust the duty cycle based on the parameter as outlined above.

[0047] The heating system may comprise a heating element e.g. a helically wound heating element (coil heating element), a mesh heater element comprising a plurality of interconnected cells that together define a heating area, e.g. formed by a perforated sheet or network of interleaved wires, or a heater track in the form of a conductive track formed on a substrate. The heating system may comprise a susceptor formed of a material configured to absorb electromagnetic energy and convert it into heat.

[0048] The heating system may generate heat via one or more of several modes. Heat may be generated by resistive heating in which a current is passed through the resistive material of the heating element (e.g. the material of a wire, coil, mesh or track). Heat may be generated by microwave heating in which microwaves are directed towards a material to be heated. Heat may be generated by inductive heating in which an electromagnetic field is generated by an inductor. The electromagnetic field generates electrical currents in a conductive material (susceptor) that induce eddy currents to heat up the conductive material. The susceptor may be positioned about the consumable (an outside-in heating arrangement) or positioned in the consumable (an inside-out heating arrangement). Heat may be generated by infrared heating in which infrared radiated in directed towards a material to be heated.

[0049] A resistive heating element may be formed from a variety of suitable materials that include, but not limited to metals, metal alloys, ceramics, ceramic metals, carbon-based materials, and composites thereof.

[0050] Examples of suitable metals and metal alloys include: silver, copper, nickel, titanium, tungsten, zirconium, tantalum, platinium group metals, stainless steel, nickel-, cobalt-, chromium-, aluminium-titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, and iron-manganese-aluminium based alloys.

[0051] The resistive heating element may comprise one or more electrically conductive tracks formed of the abovementioned metal and metal alloys.

[0052] Examples of suitable ceramics include silicon carbide, molybdenum disilicide, aluminium oxide, silicon nitride, titanium carbide. The ceramic may be doped or undoped.

[0053] In some embodiments, the heating element may be formed on or comprise an electrically insulating substrate. The electrically insulating substrate may form at least part of the wick. For example, the electrically insulating substrate may be a porous substrate. The electrically insulating substrate may be a ceramic (e.g. aluminum oxide or zirconia), polymer (e.g. polyimide), fibrous material (e.g. paper or cardboard), or other like material suitable for providing electrical insulation and mechanical support to the heating element.

[0054] The electrically insulating substrate may have a thermal conductivity of less than 40 W / mK, a thermal conductivity of less than 30 W / mK a thermal conductivity of less than 20 W / mK a thermal conductivity of less than 10 W / mK.

[0055] The heating system may comprise a susceptor configured to generate heat in the presence of an electromagnetic field. The susceptor may be formed in the shape of a rod, sheet, band, or like shape. Suitable materials include metals, ceramics, and carbon-based materials such as graphite. The metal may be a ferromagnetic metal, such as iron, stainless steel, nickel, or cobalt. The metal may be a non-ferromagnetic metal, such as aluminium, copper or gold. Suitable ceramic materials include zirconia, aluminium oxide, and silicon carbide. The susceptor may be formed of at least 50% ferro- or paramagnetic material, or at least 70% ferro- or para- magnetic material.

[0056] In some examples, the controller may be adapted to determine a rate of change of the duty cycle of the driving signal during the aerosol generation session. If the rate of change of the duty cycle exceeds a predetermined rate of change threshold, to controller may be adapted to determine that insufficient aerosol precursor is present at the aerosol-generating unit as outlined above.

[0057] A power supply may be provided to operate the aerosol-generating system. The power supply may include a battery. Suitable batteries may include lithium-based batteries (e.g. lithium-ion and lithium polymer batteries) and nickel-base batteries (e.g. nickel-cadmium and nickel-metal hydride batteries). The battery may be rechargeable via a wired or wireless connection. The power supply may, alternatively or in addition, include an external power outlet configured to charge the battery, bypass the battery, or to replace the battery altogether. The power supply may be or include another form of charge storage device such as a capacitor.

[0058] The aerosol generating system may be provided in the form of a replaceable pod and a device body. The aerosol-generating unit described above may be provided in the replaceable pod. The controller and battery may be provided in the device body.

[0059] In another aspect, the present disclosure provides a computer-readable medium comprising instructions that, when carried out by a computer, cause the computer to carry out any of the methods described herein.

[0060] The computer may, for example, be a control unit of any of the aerosol-generating apparatuses, devices or systems described herein.

[0061] The computer may, for example, be a remote computer that is communicatively connectable to any of the aerosol-generating apparatuses described herein.

[0062] The computer may, for example, be embodied as a distributed computing system including, for example, a control unit of any of the aerosol-generating apparatuses described herein and a remote computer that is communicatively connectable to any of the aerosol-generating apparatuses described herein, e.g., via a communications interface of the aerosol-generating apparatus.

[0063] In another aspect, the present disclosure provides electrical circuitry for an aerosol-generating system, the electrical circuitry being arranged to perform any of the methods described herein.

[0064] In embodiments, the electrical circuitry is implemented as one or more processors, which are configured to implement the disclosed steps, e.g. as the controller. The processors may execute program code stored on electronic memory and / or may execute logic, e.g. as a logic array, gate array, structured gate array.

[0065] As will be apparent from the present disclosure, the methods described herein may be carried out, or implemented, by a computer. The computer may, for example, be a processor installed in the aerosol-generating apparatus and configured to operate as a controller of the aerosol-generating apparatus. Alternatively, the computer may, for example, be a remote computer communicatively connectable to the aerosol-generating apparatus via a communications interface of the aerosol-generating apparatus. Alternatively, the computer may be embodied as a distributed computing environment, including for example, both a control unit installed in the aerosol-generating apparatus and a remote computer that is communicatively connectable to the control unit via a communications interface of the aerosol-generating apparatus.

[0066] Moreover, the acts described herein may be embodied using computer-executable instructions that can be implemented by one or more processors and / or stored on a computer-readable medium or media. The computer-executable instructions can include routines, sub-routines; programs; threads of execution, and / or the like. Still further, results of acts of the methods can be stored in a computer-readable medium, displayed on a display device, and / or the like.

[0067] The order of the operations of the methods described herein is exemplary, but the steps may be carried out in any suitable order, or simultaneously where appropriate. Additionally, steps may be added or substituted in, or individual steps may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

[0068] Various functions described herein can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media may include, for example, computer-readable storage media. Computer-readable storage media may include volatile or non-volatile, removable or non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. A computer-readable storage media can be any available storage media that may be accessed by a computer. By way of example, and not limitation, such computer-readable storage media may comprise RAM, ROM, EEPROM, flash memory or other memory devices, CD-ROM or other optical disc storage, magnetic disc storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0069] Although illustrated as a local device it will be appreciated that the computing device may be located remotely and accessed via a network or other communication link (for example using a communication interface).

[0070] The term 'computer' is used herein to refer to any device with processing capability such that it can execute instructions. Those skilled in the art will realise that such processing capabilities are incorporated into many different devices and therefore the term 'computer' includes PCs, servers, mobile telephones, personal digital assistants and many other devices.

[0071] Those skilled in the art will realise that storage devices utilised to store program instructions can be distributed across a network. For example, a remote computer may store an example of the process described as software. A local or terminal computer may access the remote computer and download a part or all of the software to run the program. Alternatively, the local computer may download pieces of the software as needed or execute some software instructions at the local terminal and some at the remote computer (or computer network). Those skilled in the art will also realise that by utilising conventional techniques known to those skilled in the art that all, or a portion of the software instructions may be carried out by a dedicated circuit, such as a DSP, programmable logic array, or the like.

[0072] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all the stated problems or those that have any or all of the stated benefits and advantages. Variants should be considered to be included into the scope of the invention.

[0073] 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 of the subject matter described herein in any way. Moreover, the above and / or following 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 figures.BRIEF DESCRIPTION OF THE FIGURES

[0074] Aspects, features and advantages of the present disclosure will become apparent from the following description of examples in reference to the appended figures in which like numerals denote like elements. Figure 1 shows an example of an aerosol-generating system; Figure 2 shows internal components of the aerosol-generating system; Figure 3 shows a method according to an aspect of the disclosure; Figure 4 shows a further method according to an aspect of the disclosure; Figure 5 shows a first example of a graph of duty cycle against time and a corresponding graph of heating system temperature against time; Figure 6 shows a second example of a graph of duty cycle against time and a corresponding graph of heating system temperature against time; Figure 7 shows a third example of a graph of duty cycle against time and a corresponding graph of heating system temperature against time; and Figure 8 shows an example of an ecosystem comprising an aerosol-generating system. DETAILED DESCRIPTION OF EMBODIMENTS

[0075] It is to be understood that the present disclosure, which includes the specification and claim(s), is not limited by specific construction details or process steps. Rather, it will be clear to those skilled in the art that the systems, apparatuses, and methods described herein can be embodied and practiced in various alternative ways without departing from the scope of the invention.

[0076] Unless defined otherwise, scientific and technical terms used herein have their meanings commonly understood by those skilled in the art and that known techniques and procedures may be performed according to conventional methods.

[0077] In the present disclosure, the terms "a" and "an" may mean "one", "one or more", "at least one", and "one or more than one" unless the context clearly indicates otherwise. Likewise, plural terms shall include the singular unless otherwise required by context.

[0078] In the present disclosure, the term "or" means an inclusive "and / or" unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive.

[0079] In the present disclosure, the terms "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.

[0080] As used herein, the term "interface" relates to an element through which information can be transmitted, through which information can be received, or through which information can be both transmitted and received.

[0081] Examples of interfaces may include interfaces configured to convey information from the device to a user, namely output elements such as visual display elements, auditory elements, haptic elements, and / or interfaces configured to convey information from a user to the device, namely input elements such as buttons, dials, and sensory elements. Examples of sensory elements include touch screens, motion sensors, proximity sensors and auditory sensors.

[0082] As used herein, the term "haptic element" relates to an element configured to transmit tactile information to a user via the user's sense of touch. Typically, the user detects a haptic output from the haptic element at a predefined portion of the device. The user may detect the haptic output when contacting the haptic element directly or indirectly via one or more components of the device. The haptic output may comprise one or more of (e.g.) force, vibration, electro, ultrasonic, and thermal feedback that can be sensed by the user. The haptic element may be a mechanical actuator, piezoelectric actuator, thermal element, electromagnetic actuator, or ultrasonic actuator.

[0083] As used herein, the term "auditory element" relates to an element configured to generate a sound or auditory signal perceptible to a user. The term "auditory sensor" relates to a sensor configured to detect sound waves or auditory signals.

[0084] 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 cutouts to encode a bit, through which pins or a reader may be inserted).

[0085] 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 device, or distributed between the device and / or on one or more external devices in communication with the device, e.g. as part of the system.

[0086] 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. 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 device 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 an aerosol-generating system as disclosed herein, and may therefore be used synonymously with the term method.

[0087] As used herein, an "external device" (or "peripheral device") may include one or more electronic components external to an aerosol-generating system. Those components may be arranged at the same location as the device or remote from the device. 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.

[0088] 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 a system disclosed herein to perform a method as disclosed herein.

[0089] As used herein, a "communication resource" (or "communication interface") may refer to hardware and / or firmware for electronic information / data transfer. The communication resource may be configured for wired communication ("wired communication resources") or wireless communication ("wireless communication resource"). Wireless communication resources may include hardware to transmit and receive signals by radio and may include various protocol implementations e.g. the 802.11 standard described in the Institute of Electronics Engineers (IEEE) and Bluetooth ™< from the Bluetooth Special Interest Group of Kirkland Wash. Wired communication resources may include; Universal Serial Bus (USB); High-Definition Multimedia Interface (HDMI) or other protocol implementations. The system may include communication resources for wired or wireless communication with an external device.

[0090] As used herein, a "network" (or "computer network") may refer to a system for electronic information / data transfer between a plurality of apparatuses / devices. The network may, for example, include one or more networks of any type, which may include: a Public Land Mobile Network (PLMN); a telephone network (e.g. a Public Switched Telephone Network (PSTN) and / or a wireless network); a local area network (LAN); a metropolitan area network (MAN); a wide area network (WAN); an Internet Protocol Multimedia Subsystem (IMS) network; a private network; the Internet; an intranet.

[0091] It will be appreciated that any of the disclosed methods (or corresponding systems, programs, data carriers, etc.) may be carried out by either a host or client, depending on the specific implementation (i.e. the disclosed methods / systems 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.

[0092] Unless stated otherwise, the features of examples disclosed herein, and of the claims, may be integrated together in any suitable arrangement such that combinations of features are not limited by the described forms, particularly the form (e.g. numbering) of example(s), embodiment(s), or dependency of claim(s). This also applies to the phrase "in one example", "according to an example" and the like, which are merely a stylistic form of wording not to be construed as limiting the features to a separate embodiment. This is to say, a reference to 'an,' 'one,' or 'some' examples(s) may be a reference to any one or more, and / or all examples, or combination(s) thereof, disclosed. Also, similarly, reference to "the" example 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.

[0093] 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.

[0094] Figure 1 shows an example of an aerosol-generating system 1. In this example, the aerosol-generating system 1 is an electronic vapour product (EVP) configured to produce an aerosol from an aerosol-forming material 10 (e.g. a liquid or gel precursor), although it will be appreciated that the invention may be similarly applicable to a heat-not-burn product (HNB) configured to produce an aerosol from heating an aerosol-forming material (e.g. a solid precursor such as tobacco) to a temperature below its combustion temperature.

[0095] The term "aerosol-forming material" refers to a substrate or formulation capable of releasing volatile components that can form an aerosol, e.g. by releasing volatile compounds in the aerosol-forming material. An "aerosol" is a dispersion of solid particles and / or liquid droplets dispersed in a gas. The aerosol may be visible or invisible.

[0096] Figure 2 shows a schematic representation of the internal components of the aerosol-generating system 1. The aerosol-generating system 1 comprises an aerosol-generating unit 2 configured to generate an aerosol from an aerosol-forming material 10 held in a storage portion 3 of the aerosol-generating system 1 (implemented here as a "tank"). In this example, the aerosol-generating unit 2 is a heating system including a heating element 2a although it will be appreciated that an aerosol-generating unit comprising an ultrasonic element, atomiser or similar component may be provided.

[0097] The aerosol-forming material 10 may be referred to as "e-liquid". Typically, the aerosol-forming material 10 includes a base liquid and optionally nicotine and / or flavourings such that the resulting aerosol contains nicotine and / or flavourings.

[0098] The aerosol-generating system 1 includes a power source 4. In this example, the power source 4 includes a battery 4a configured to supply electrical energy to operate the aerosol-generating unit 2 and other components. The aerosol-generating system 1 may be powered, alternatively or in addition to the battery 4a, by an external power source. In an alternative example, the power source 4 may be omitted, e.g. an aerosol aerosol-generating unit implemented as an atomiser with flow expansion may not require a power supply.

[0099] The aerosol-generating system 1 includes an aerosol-delivery system 5 for delivery of the aerosol to a user. In this example, the aerosol-delivery system 5 comprises an air inlet 6, a mouthpiece 8, and an air passageway 7 extending therebetween via a region in proximity to the aerosol-generating unit 2.

[0100] The aerosol-generating unit 2 includes a wick 2b having at least one end that extends into the storage portion 3 and is configured to draw aerosol-forming material 10 out from the storage portion 3. In this example, the heating element 2a is in the form of a heating filament wrapped around a portion of the wick 2b. In this manner, the heating element 2a can heat up the aerosol-forming material 10 drawn out of the storage portion 3 by the wick 2b to produce the aerosol, which is then drawn through the air passageway 7 to the mouthpiece 8. In other examples, the heating element 2a may be a mesh heater, ceramic heater, or other means of generating heat. The heating element 2a may be part of an induction heater having a susceptor configured to produce heat when penetrated by an alternating magnetic field.

[0101] The aerosol-generating system 1 may be a two-part construction comprising a device body 20 and an article 30 (alternatively referred to as a "pod" or "cartomizer") configured to be releasably connected / disconnected by an end user. The device body 20 and article 30 are each configured to house respective components of the aerosol-generating system 1.

[0102] In some examples, the article 30 may be configured to be disposed of upon depletion of aerosol-forming material 10 from the storage portion, in which case the article 30 may referred to as a "consumable". Alternatively, the article 30 may be configured for reuse, such that it is configured to be refillable upon depletion of the aerosol-forming material 10 from the storage portion.

[0103] In this example, the device body 20 comprises the power source 4, and the article 30 comprises the aerosol-generating unit 2 and storage portion 3, although it will be appreciated that the device body 20 and article 30 may house any respective set of components. The device body 20 and article 30 are configured to physically interlock to secure the article 30 relative to the device body 20.

[0104] Upon connection, electrical connectors 40 of the device body 20 and article 30 may establish an electrical connection between the device body 20 and the article 30. In this way, electrical power can be supplied from the power source 4 to the aerosol-generating unit 2 (or other components of the article 30) without the article 30 needing to have its own power supply.

[0105] The device body 20 may include any one or more of electrical circuitry, a memory, a wireless interface, and one or more other components. The device body 20 may include a printed circuit board (PCB) on which components of the electrical circuitry, memory, wireless interface, and other components may be mounted.

[0106] The electrical circuitry may include a processing resource for controlling one or more operations of the body 20 and article 30, e.g. based on instructions stored in the memory. The wireless interface may be configured to communicate wirelessly with an external (e.g. mobile) device, e.g. via Bluetooth. The other component(s) may include one or more user interface devices configured to convey information to a user, a pressure sensor 15, and / or a charging port 18 (see e.g. figure 2).

[0107] The aerosol-generating system 1 may comprise one or more input and / or output elements. In this example, the aerosol-generating system 1 includes an input element in the form of a pressure sensor 15 arranged to detect a "puff" of the user, and particularly the resultant change in air pressure, i.e. a vacuum pressure generated by the user. Alternatively, or in addition, the aerosol-generating system 1 may include other means of detecting airflow, such as a flowmeter or microphone. The user can thereby activate the aerosol-generating unit 2 when inhaling through the mouthpiece 8. The aerosol-generating unit 2 creates an aerosol which is carried by the flow through the air passageway 7 and out of the mouthpiece 8.

[0108] The input and / or output elements may form part of a user interface (UI) of the aerosol-generating system 1. For instance, figure 2 shows an output element in the form of a light (e.g. an LED) 17. The light 17 is configured to convey information to the user regarding the state of the system 1. It will be appreciated that the input element(s) may be provided in various forms, such as touch screens, switches, and sensors, and the output element(s) may be provided in various forms, such as display screens, speakers, or a haptic output generated by a vibration generator.

[0109] Figure 3 shows a method 100 for determining whether insufficient aerosol precursor is present at an aerosol-generating unit 2 of an aerosol-generating system 1. In particular, the method 100 described herein may be a method for determining whether insufficient aerosol precursor, or aerosol -forming material 10, is present at the wick 2b of the aerosol-generating unit 2.

[0110] The method may begin in step 110 by receiving an activation signal for activating the aerosol-generating unit 2. The activation signal may be generated by the pressure sensor 15 in response to a "puff" of the user.

[0111] From step 110 the method 100 may progress to step A, which is described in further detail below with respect to Figure 4. Otherwise, the method progresses to step 120, wherein, in response to receiving the activation signal in step 110, it is determined that an aerosol generation session has started at a first point in time. The aerosol generation session may last as long as the user is inhaling and a "puff" is detected by the pressure sensor 15.

[0112] The method 100 progresses to step 130 in which a driving signal is generated to cause the aerosol-generating unit 2 to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle. The driving signal may cause the heating element 2a to heat the aerosol precursor, or aerosol - forming material 10, in the wick 2b in order to generate an aerosol.

[0113] The driving signal is generated with an initial duty cycle; however, the duty cycle of the driving signal may be controlled using PWM to vary the duty cycle over the course of the aerosol generation session. The duty cycle may be varied based on a parameter of the aerosol-generating unit 2.

[0114] In particular, in step 140, the temperature of the heating element 2a may be monitored and the duty cycle of the driving signal may be adjusted in step 150 based on the temperature of the heating element 2a. As outlined in further detail below with respect to Figures 5 to 7, the duty cycle of the driving signal may be reduced as the temperature of the heating element 2a increases.

[0115] In step 160, the duty cycle of the driving signal, and any variation in the duty cycle of the driving signal, is monitored during the aerosol generation session. The method progresses to step 170 when it is determined that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold (e.g., below 20% or below 10%), which marks a second point in time after the first point in time.

[0116] The method 100 then progresses to step 180 where the time period between the first point in time (i.e., when the aerosol generation session began) and the second point in time (i.e., when the duty cycle fell below the predetermined threshold) is compared to a reference time period (e.g., which may be a time period of one second or less). If the time period is less than the reference time period, the method progresses to step 190, in which it is determined that insufficient aerosol precursor is present at the aerosol-generating unit 2. The aerosol-generating unit 2 may be deactivated in response to the determination in step 190. If the time period is greater than, or equal to, the reference time period, the aerosol-generating system may continue to operate as normal.

[0117] Figure 4 shows a method 200 for controlling an aerosol-generating unit of an aerosol-generating system. The method begins in step A, which is preceding by step 110 in the method 100 shown in Figure 3.

[0118] In step 210, it is determined that a new aerosol generation session has started. Determining that a new aerosol generation session has started may comprise the same steps as determining that an aerosol generation session has begun at a first point in time in step 120 outlined above with respect to Figure 3.

[0119] The method 200 may then progress to step 220 where an elapsed time between the new aerosol generation session and a previous aerosol generation session, immediately preceding the new aerosol generation session, is obtained.

[0120] In step 230 the elapsed time obtained in step 220 is compared to a predetermined elapsed time threshold. If the elapsed time is greater than, or equal to, the predetermined elapsed time threshold (e.g., two seconds or more), the method progresses to step B, and returns to the method 100 for determining whether insufficient aerosol precursor is present at the aerosol-generating unit 2 as described above with reference to Figure 3.

[0121] If in step 230 it is found that the elapsed time is less than the predetermined elapsed time threshold, the method may progress to step 240 in which an aerosol is generated using the aerosol-generating unit 2.

[0122] Figure 5 shows a first example of a graph 300 of duty cycle against time and a corresponding graph 350 of heating system temperature against time. Figure 6 shows a second example of a graph 400 of duty cycle against time and a corresponding graph 450 of heating system temperature against time.

[0123] Figure 7 shows a third example of a graph 500 of duty cycle against time and a corresponding graph 550 of heating system temperature against time.

[0124] In each of the examples in Figures 5 to 7, it has been assumed that the heating system has the same initial starting temperature. Accordingly, the primary variable between the three examples illustrated in Figures 5 to 7 is the amount of aerosol precursor, i.e., aerosol forming material 10, present at the aerosol-generating unit 2, i.e., at the wick 2b.

[0125] The example shown in Figure 5 illustrates an example where the wick 2b of the aerosol-generating unit 2 is fully saturated with aerosol precursor.

[0126] In the example shown in Figure 5, the graph 300 of duty cycle against time shows a driving signal across an aerosol generation session, which has been divided into five periods 310a to 310e. Each period has an associated duty cycle 320a to 320e. The driving signal begins when the aerosol generation session is determined to have started, as described above, at the first point in time, t 1 .

[0127] The corresponding graph 350 of temperature against time shows a plot 360 of the change in temperature of the heating element 2a of the aerosol-generating unit over the course of the aerosol generation session in response to the driving signal illustrated in graph 300.

[0128] As shown in Figure 5, the rate of change of the temperature of the heating element 2a is relatively low when the wick 2b is saturated with aerosol precursor. Accordingly, in the first three periods 310a, 310b and 310c of the aerosol generation session, the duty cycles 320a, 320b and 320c are relatively high (e.g., 80%).

[0129] As the temperature of the heating element 2a approaches the target temperature 370 for aerosol generation, the duty cycles 320d and 320e in periods 310d and 310e are gradually reduced in order to slow the rise in temperature of the heating element 2a.

[0130] In the example shown in Figure 5, the duty cycle does not fall below the predetermined duty cycle threshold, and so there is no determination that insufficient aerosol precursor is present at the aerosol generating unit 2.

[0131] The example shown in Figure 6 illustrates an example where sufficient aerosol precursor for aerosol generation is present at the wick 2b of the aerosol-generating unit 2, but the wick is not saturated, for example because the aerosol-generating system contains less than the full amount of aerosol precursor.

[0132] In the example shown in Figure 6, the graph 400 of duty cycle against time shows a driving signal across an aerosol generation session, which has been divided into five periods 410a to 410e. Each period has an associated duty cycle 420a to 420e. The driving signal begins when the aerosol generation session is determined to have started, as described above, at the first point in time, t 1 .

[0133] The corresponding graph 450 of temperature against time shows a plot 460 of the change in temperature of the heating element 2a of the aerosol-generating unit over the course of the aerosol generation session in response to the driving signal illustrated in graph 400.

[0134] As shown in Figure 6, the rate of change of the temperature of the heating element 2a is higher when sufficient aerosol precursor is present at the wick 2b, but the wick 2b is not fully saturated, compared to the example shown in Figure 5. Accordingly, in the first period 410a of the aerosol generation session, the duty cycle 420a is relatively high (e.g., 80%), but in the second period 410b and the third period 410c the duty cycles 420b and 420c are gradually reduced due to the more rapid rise in temperature of the heating element 2a.

[0135] By the beginning of the fourth period 410d, the duty cycle has fall below the predetermined duty cycle threshold 430 (e.g., below 20%) and the temperature of the heating element 2a is being maintained around the target temperature 470. The duty cycle is determined to have fallen below the predetermined duty cycle threshold 430 at a second point in time, t 2 .

[0136] The time period, Δt, between the first point in time, t 1 , and the second point in time, t 2 , is compared to a reference time period in order to determine whether insufficient aerosol precursor is present at the wick 2b. In the example shown in Figure 6, the time period, Δt, exceeds the reference time period because sufficient aerosol precursor is present at the aerosol-generating unit 2.

[0137] The example shown in Figure 7 illustrates an example where insufficient aerosol precursor for aerosol generation is present at the wick 2b of the aerosol-generating unit 2, for example because the aerosol-generating system contains little to no aerosol precursor.

[0138] In the example shown in Figure 7, the graph 500 of duty cycle against time shows a driving signal across an aerosol generation session, which has been divided into five periods 510a to 510e. Each period has an associated duty cycle 520a to 520e. The driving signal begins when the aerosol generation session is determined to have started, as described above, at the first point in time, t 1 .

[0139] The corresponding graph 550 of temperature against time shows a plot 560 of the change in temperature of the heating element 2a of the aerosol-generating unit over the course of the aerosol generation session in response to the driving signal illustrated in graph 500.

[0140] As shown in Figure 7, the rate of change of the temperature of the heating element 2a is higher when insufficient aerosol precursor is present at the wick 2b, compared to the examples shown in Figures 5 and 6. Accordingly, in the first period 510a of the aerosol generation session, the duty cycle 520a is relatively low (e.g., 50%), but in the second period 510b the duty cycle 520b has already fallen below the predetermined duty cycle threshold 530 (e.g., below 20%) due to the rapid rise in temperature of the heating element 2a. The duty cycle is determined to have fallen below the predetermined duty cycle threshold 530 at a second point in time, t 2 .

[0141] The time period, Δt, between the first point in time, t 1 , and the second point in time, t 2 , is compared to a reference time period in order to determine whether insufficient aerosol precursor is present at the wick 2b. In the example shown in Figure 7, the time period, Δt, is less than the reference time period because insufficient aerosol precursor is present at the aerosol-generating unit 2.

[0142] In the example shown in Figure 7, the determination that insufficient aerosol precursor is present at the wick 2b may also have been made based on the rate of change of duty cycle in response to the rapid rise in temperature of the heating element 2a, for example within the first period 510a.

[0143] Figure 8 shows an example of an ecosystem 50 comprising an aerosol-generating system 1, a mobile device 52, an application server 54, and a charging station 56.

[0144] In this example, the aerosol-generating system 1 is configured to communicate wirelessly, e.g. via Bluetooth ™< , with an application (or "app") installed on the mobile device 52, via a wireless interface included in the aerosol-generating system 1 and via a wireless interface included in the mobile device 52. The mobile device 52 may be a mobile phone, for example. The application on the mobile device 52 may be configured to communicate with the application server 54, via a network 58. The application server 54 may utilise cloud storage, for example.

[0145] The network 58 may include a cellular network and / or the internet.

[0146] In other examples, the aerosol-generating system 1 may be configured to communicate with the application server 54 via a connection that does not involve the mobile device 52, e.g. via a narrowband internet of things ("NB-IoT") or satellite connection. In some examples, the mobile device 52 may be omitted from the ecosystem 50.

[0147] A skilled person would readily appreciate that the mobile device 52 may be configured to communicate via the network 58 according to various communication channels, for instance a wireless communication channel such as via a cellular network (e.g. according to a standard protocol, such as 3G or 4G) or via a WiFi network.

[0148] The app installed on the mobile device 52 and the application server 54 may be configured to assist a user with managing the aerosol-generating system 1, based on information communicated between the aerosol-generating system 1 and the app, information communicated directly between the aerosol-generating system 1 and the application server 54, and / or information communicated between the app and the application server 54.

[0149] The charging station 56 (if present) may be configured to charge (and optionally communicate with) the aerosol-generating system 1, via a charging port 18 on the aerosol-generating system 1. The charging port 18 on the aerosol-generating system 1 may be a USB port, for example, which may allow the aerosol-generating system 1 to be charged by any USB-compatible device capable of delivering power to the aerosol-generating system 1 via a suitable USB cable (in this case the USB-compatible device would be acting as the charging station 56). Alternatively, the charging station could be a docking station configured to dock with the aerosol-generating system 1 and charge the aerosol-generating system 1 via the charging port 18 on the aerosol-generating system 1.

Examples

Embodiment Construction

[0075]It is to be understood that the present disclosure, which includes the specification and claim(s), is not limited by specific construction details or process steps. Rather, it will be clear to those skilled in the art that the systems, apparatuses, and methods described herein can be embodied and practiced in various alternative ways without departing from the scope of the invention.

[0076]Unless defined otherwise, scientific and technical terms used herein have their meanings commonly understood by those skilled in the art and that known techniques and procedures may be performed according to conventional methods.

[0077]In the present disclosure, the terms "a" and "an" may mean "one", "one or more", "at least one", and "one or more than one" unless the context clearly indicates otherwise. Likewise, plural terms shall include the singular unless otherwise required by context.

[0078]In the present disclosure, the term "or" means an inclusive "and / or" unless explicitly indicated to...

FIELD

[0001] The present disclosure relates to systems and methods for determining whether insufficient aerosol precursor is present at an aerosol-generating unit.BACKGROUND

[0002] An electronic vapour product (EVP), also known as a vaping apparatus or a vape, is a type of aerosol-generating system in which an aerosol precursor (e.g. a liquid or gel) is aerosolised by an aerosol-generating unit, such as a heating element or ultrasonic element.

[0003] An aerosol-generating unit may cease to function, or become damaged, if driven in the absence of aerosol precursor at the aerosol-generating unit. The burden of determining whether sufficient aerosol precursor is present in the aerosol-generating unit is typically placed on the user and is often a matter of visual inspection by the user, which can be challenging to perform with any accuracy.

[0004] It is against this background that the present invention has been developed.SUMMARY

[0005] The present disclosure provides a method for determining whether insufficient aerosol precursor is present at an aerosol-generating unit of an aerosol-generating system.

[0006] The method comprises the steps of determining that an aerosol generation session has started at a first point in time and generating a driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle.

[0007] It will be understood that the term duty cycle, which may also be referred to as power cycle or duty factor, refers to the percentage of time that a system or signal is active within a period, the period being the time for a signal to complete a cycle of ON and OFF. For example, for a signal having a period of 1s, a duty cycle of 50% means that the signal includes 0.5s of an ON signal and 0.5s of an OFF signal. For example, for a signal having a period of 2s, a duty cycle of 25% means that the includes 0.5s of an ON signal and 1.5s of an OFF signal. A duty cycle of 100% will mean that the signal is always ON and a duty cycle of 0% will means the signal is always OFF. Duty cycle may be represented either by a percentage or a ratio.

[0008] The duty cycle of the driving signal may be variable. The duty cycle of the driving signal may be controlled using pulse width modulation (PWM). PWM may be used to control the variation of the duty cycle over time.

[0009] The duty cycle of the driving signal may be varied in order to control the average power delivered to the aerosol-generating unit for generating the aerosol. As outlined in further detail below, the behaviour and voltage requirements of the aerosol-generating unit may vary across the aerosol generation session, and so the duty cycle may be varied over the aerosol generation session accordingly.

[0010] In some examples, the method may comprise monitoring the duty cycle of the driving signal during the aerosol generation session. For example, where the duty cycle varies over the aerosol generation session, monitoring the duty cycle of the driving signal may comprise monitoring the variation in the duty cycle of the driving signal over time.

[0011] In some examples, the method may comprise determining that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time. The second point in time may be after the first point in time. In some examples, the predetermined duty cycle threshold may be around 20% or less, for example around 10% or less.

[0012] For example, if the duty cycle of the driving signal is varied in order to control the average power delivered to the aerosol-generating unit, the duty cycle may be reduced over the course of the aerosol generation session. A reduction in the duty cycle of the driving signal, and so a reduction in the power delivered to aerosol-generating unit, may be indicative of a problem with the aerosol-generating unit.

[0013] For example, if insufficient aerosol precursor is present at the aerosol-generating unit, a parameter of the aerosol-generating unit may change to be outside of an acceptable range. In response, the duty cycle of the driving signal may be reduced in order to prevent damage to the aerosol-generating unit, or to prevent an inferior aerosol from being generated by the aerosol-generating unit.

[0014] Insufficient aerosol precursor may be understood to mean an absence or a partial absence, of aerosol precursor at the aerosol-generating unit. For example, in order to generate an acceptable aerosol, the aerosol-generating unit may require a predetermined amount of aerosol precursor. If the amount of aerosol precursor at the aerosol-generating unit is greater than, or equal to, the predetermined amount of aerosol precursor, then it may be considered that sufficient aerosol precursor is present at the aerosol-generating unit. If the amount of aerosol precursor at the aerosol-generating unit is less than the predetermined amount of aerosol precursor, then it may be considered that insufficient aerosol precursor is present at the aerosol-generating unit.

[0015] In some examples, the aerosol precursor may be a liquid or a gel. In such an example, insufficient aerosol precursor being present at the aerosol-generating unit may result in the aerosol-generating unit, or a part of the aerosol-generating unit (such as a wick), being dry.

[0016] In some examples, a time period between the first point in time and the second point in time may be compared to a reference time period. If the time period is less than the reference time period, the method may comprise determining that insufficient aerosol precursor is present at the aerosol-generating unit. In some examples, the reference time period around one second or less, for example around half a second or less.

[0017] For example, an aerosol generation session may comprise at least some variation in the duty cycle of the driving signal. The duty cycle may be varied over the course of the aerosol generation session to account for changes in a parameter of the aerosol-generating unit or for changes in the amount of aerosol precursor present at the aerosol-generating unit.

[0018] However, a rapid reduction in the duty cycle of the driving signal, i.e., the duty cycle falling below the predetermined threshold within the reference time period, may be indicative of a problem with the aerosol-generating unit, such as insufficient aerosol precursor being present at the aerosol-generating unit.

[0019] In other words, there is provided a means of determining that an insufficient amount of aerosol precursor is present at an aerosol-generating unit based on the duty cycle, and in particular based on changes in the duty cycle, of a signal for driving the aerosol-generating unit.

[0020] Put another way, by monitoring the duty cycle of the signal for driving the aerosol-generating unit, it can be determined whether the aerosol-generating unit is functioning correctly, for example is being supplied with sufficient aerosol precursor for aerosol generation.

[0021] Determining that insufficient aerosol precursor is present at the aerosol-generating unit may comprise one or more of: determining that a supply of the aerosol precursor has been exhausted; determining that insufficient time has elapsed between the first point in time and the second point in time and, determining that a supply of the aerosol precursor is impeded from reaching the aerosol-generating unit.

[0022] In some examples, the method further comprises monitoring a parameter of the aerosol-generating unit during the aerosol generation session. In some examples, a plurality of parameters of the aerosol-generating unit may be monitored during the aerosol generation session. The method may further comprise adjusting the duty cycle based on the parameter(s).

[0023] The parameter(s) of the aerosol-generating unit may comprise one or more of: an electrical characteristic of the aerosol-generating unit; and a physical characteristic of the aerosol-generating unit. The electrical characteristic of the aerosol-generating unit may comprise one or more of: a current; a voltage; and a resistance. The physical characteristic of the aerosol-generating unit may comprise a temperature of the aerosol-generating unit.

[0024] In some examples, the aerosol-generating unit comprises a heating system for heating the aerosol precursor to generate an aerosol. The (physical) parameter of the aerosol-generating unit may comprise a temperature of the heating system.

[0025] For example, the temperature of the heating system may be monitored during the aerosol generation session. An aerosol precursor may have an aerosolization temperature at which aerosol is produced. Accordingly, the heating system may be driven to reach and maintain the aerosolization temperature over the course of an aerosol generation session.

[0026] If the heating system is starting from a relatively low temperature, such as ambient temperature, the duty cycle of the driving signal may be initially higher in order to deliver a higher average power to the heating system in order to increase the temperature of the heating system quickly for aerosol production. As the temperature of the heating system approaches the aerosolization temperature, the duty cycle of the driving signal may be decreased in order to slow the rise in temperature so as not to overshoot the aerosolization temperature and burn the aerosol precursor. When the temperature of the heating system has reached the aerosolization temperature, the duty cycle of the driving signal may be brought to a minimum level, for example a duty cycle of around 10%, required to maintain the temperature of the heating system at the aerosolization temperature for the remaining time of the aerosol generation session.

[0027] If the heating system is starting from a relatively high temperature, the duty cycle of the driving signal may be initially lower and decrease more rapidly than for a heating system starting at a lower temperature.

[0028] In the example where the aerosol precursor is a liquid, the amount of liquid aerosol precursor present at the aerosol-generating unit may affect how the temperature of the heating system changes in response to the driving signal.

[0029] For example, an aerosol-generating unit having sufficient aerosol precursor liquid, i.e., an amount of aerosol precursor greater than or equal to a predetermined amount of aerosol precursor liquid, present may require a higher initial duty cycle at the start of an aerosol generation session to bring the temperature of the heating system up to the aerosolization temperature as a portion of the thermal energy may be absorbed by the aerosol precursor liquid. Once again, when the temperature of the heating system has reached the aerosolization temperature, the duty cycle of the driving signal may be reduced to maintain the temperature of the heating system at the aerosolization temperature.

[0030] For example, an aerosol-generating unit having insufficient aerosol precursor liquid, i.e. less than a predetermined amount of aerosol precursor liquid, present may result in the temperature of the heating system reaching the aerosolization temperature more rapidly than when there is sufficient aerosol precursor liquid present at the aerosol-generating unit. Therefore, if insufficient aerosol precursor liquid is present at the aerosol-generating unit, the duty cycle of the driving signal may drop more rapidly towards the maintenance level of the duty cycle, for example 10%.

[0031] Accordingly, for a newly initiated aerosol generation session in which the heating system is at a relatively low temperature, for example after a sufficient period has elapsed since the previous aerosol generation session, a rapid decrease in duty cycle (i.e., the duty cycle falling below the predetermined duty cycle threshold within the predetermined time period) may indicate that the heating system is heating too quickly due to an absence of aerosol precursor liquid, for example rather than due to any latent heat of the heating system itself.

[0032] The determination that insufficient aerosol precursor is present at the aerosol-generating unit may be indicative that the aerosol precursor supply is exhausted or that the aerosol precursor has not had sufficient time to reach, and replenish, the aerosol-generating unit since a previous aerosol generation session.

[0033] In some examples, the method may comprise determining a rate of change of the duty cycle of the driving signal during the aerosol generation session. If the rate of change of the duty cycle exceeds a predetermined rate of change threshold, the method may comprise determining that insufficient aerosol precursor is present at the aerosol-generating unit.

[0034] In the examples outlined above, the method may await the duty cycle falling below the predetermined duty cycle threshold before determining that insufficient aerosol precursor is present at the aerosol-generating unit. In some examples, the method may comprise determining that insufficient aerosol precursor is present at the aerosol-generating unit based on the rate of change of the duty cycle, for example how quickly the duty cycle is decreasing during the aerosol generation session.

[0035] For example, the duty cycle of the driving signal may be around 80% at the start of an aerosol generation session and may decrease over the course of the aerosol generation session towards a maintenance duty cycle, for example of around 10%. As outlined above, if the duty cycle falls below the predetermined duty cycle threshold, for example below around 10%, it may be determined that insufficient aerosol precursor is present at the aerosol-generating unit. Additionally, if the duty cycle falls too rapidly towards the predetermined duty cycle threshold, it may also be determined that insufficient aerosol precursor is present at the aerosol-generating unit. For example, from an initial duty cycle, a rate of change of duty cycle of over 50% per second may exceed a predetermined rate of change threshold.

[0036] In some examples, determining that the aerosol generation session has started may comprise receiving an activation signal for activating the aerosol-generating unit. The method may comprise determining that the aerosol-generating session has started based on the activation signal.

[0037] The activation signal may be any signal for causing the aerosol-generating unit to generate an aerosol. For example, where the aerosol-generating unit comprises a heating system, the activation signal may be a signal for activating the heating system to generate heat for heating the aerosol precursor to form an aerosol. The activation signal may be received from any suitable source for generating an activation signal. For example, the activation signal may be received from a user interface configured to receive a user input and, responsive to the user input, to generate the activation signal. The user interface may comprise a button or switch. The user interface may comprise a pressure sensor for detecting a puff of the user.

[0038] The present disclosure may further provide a method for controlling an aerosol-generating unit of an aerosol-generating system. In some examples, the method may comprise determining that a new aerosol generation session has started. Determining that a new aerosol generation session has started may comprise the same steps as determining that an aerosol generation session has begun at a first point in time outlined above.

[0039] In some examples, the method may comprise obtaining an elapsed time between the new aerosol generation session and a previous aerosol generation session. The previous aerosol generation session may be the aerosol generation session immediately preceding the new aerosol generation session, i.e., there may be no intermediate aerosol generation sessions between the previous aerosol generation session and the new aerosol generation session.

[0040] In some examples, the elapsed time may be compared to a predetermined elapsed time threshold. If the elapsed time is greater than, or equal to, the predetermined elapsed time threshold, the method may comprise determining whether insufficient aerosol precursor is present at the aerosol-generating unit of the aerosol-generating system according to the methods described above. If the elapsed time is less than the predetermined elapsed time threshold, the method may comprise generating an aerosol using the aerosol-generating unit. In some examples, the elapsed time period is greater than around two seconds, for example greater than around three, four or five seconds.

[0041] In some examples, an aerosol generation session may correspond to a single inhalation by a user. Accordingly, if the elapsed time between a new aerosol generation session and a previous aerosol generation session is below a predetermined elapsed time threshold, the user may be performing consecutive inhalations using the aerosol-generating system.

[0042] The present disclosure may further provide an aerosol-generating system. The aerosol-generating system may comprise an aerosol-generating unit for generating an aerosol from an aerosol precursor and a controller. In some examples, the aerosol precursor may be a liquid or a gel. The controller may be adapted to perform the method steps outlined above.

[0043] In some examples, the controller may be adapted to determine that an aerosol generation session has started at the first point in time and generate the driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle.

[0044] In some examples, the controller may monitor the duty cycle of the driving signal during the aerosol generation session and determine that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time.

[0045] In some examples, the controller may compare a time period between the first point in time and the second point in time to a reference time period and, if the time period is less than the reference time period, determine that insufficient aerosol precursor is present at the aerosol-generating unit.

[0046] In some examples, the aerosol-generating unit may comprise a heating system. The controller may be adapted to monitor a parameter of the aerosol-generating unit during the aerosol generation session. In some examples, the parameter may comprise a temperature of the heating system. The controller may be adapted to adjust the duty cycle based on the parameter as outlined above.

[0047] The heating system may comprise a heating element e.g. a helically wound heating element (coil heating element), a mesh heater element comprising a plurality of interconnected cells that together define a heating area, e.g. formed by a perforated sheet or network of interleaved wires, or a heater track in the form of a conductive track formed on a substrate. The heating system may comprise a susceptor formed of a material configured to absorb electromagnetic energy and convert it into heat.

[0048] The heating system may generate heat via one or more of several modes. Heat may be generated by resistive heating in which a current is passed through the resistive material of the heating element (e.g. the material of a wire, coil, mesh or track). Heat may be generated by microwave heating in which microwaves are directed towards a material to be heated. Heat may be generated by inductive heating in which an electromagnetic field is generated by an inductor. The electromagnetic field generates electrical currents in a conductive material (susceptor) that induce eddy currents to heat up the conductive material. The susceptor may be positioned about the consumable (an outside-in heating arrangement) or positioned in the consumable (an inside-out heating arrangement). Heat may be generated by infrared heating in which infrared radiated in directed towards a material to be heated.

[0049] A resistive heating element may be formed from a variety of suitable materials that include, but not limited to metals, metal alloys, ceramics, ceramic metals, carbon-based materials, and composites thereof.

[0050] Examples of suitable metals and metal alloys include: silver, copper, nickel, titanium, tungsten, zirconium, tantalum, platinium group metals, stainless steel, nickel-, cobalt-, chromium-, aluminium-titanium- zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese- and iron-containing alloys, and super-alloys based on nickel, iron, cobalt, stainless steel, and iron-manganese-aluminium based alloys.

[0051] The resistive heating element may comprise one or more electrically conductive tracks formed of the abovementioned metal and metal alloys.

[0052] Examples of suitable ceramics include silicon carbide, molybdenum disilicide, aluminium oxide, silicon nitride, titanium carbide. The ceramic may be doped or undoped.

[0053] In some embodiments, the heating element may be formed on or comprise an electrically insulating substrate. The electrically insulating substrate may form at least part of the wick. For example, the electrically insulating substrate may be a porous substrate. The electrically insulating substrate may be a ceramic (e.g. aluminum oxide or zirconia), polymer (e.g. polyimide), fibrous material (e.g. paper or cardboard), or other like material suitable for providing electrical insulation and mechanical support to the heating element.

[0054] The electrically insulating substrate may have a thermal conductivity of less than 40 W / mK, a thermal conductivity of less than 30 W / mK a thermal conductivity of less than 20 W / mK a thermal conductivity of less than 10 W / mK.

[0055] The heating system may comprise a susceptor configured to generate heat in the presence of an electromagnetic field. The susceptor may be formed in the shape of a rod, sheet, band, or like shape. Suitable materials include metals, ceramics, and carbon-based materials such as graphite. The metal may be a ferromagnetic metal, such as iron, stainless steel, nickel, or cobalt. The metal may be a non-ferromagnetic metal, such as aluminium, copper or gold. Suitable ceramic materials include zirconia, aluminium oxide, and silicon carbide. The susceptor may be formed of at least 50% ferro- or paramagnetic material, or at least 70% ferro- or para- magnetic material.

[0056] In some examples, the controller may be adapted to determine a rate of change of the duty cycle of the driving signal during the aerosol generation session. If the rate of change of the duty cycle exceeds a predetermined rate of change threshold, to controller may be adapted to determine that insufficient aerosol precursor is present at the aerosol-generating unit as outlined above.

[0057] A power supply may be provided to operate the aerosol-generating system. The power supply may include a battery. Suitable batteries may include lithium-based batteries (e.g. lithium-ion and lithium polymer batteries) and nickel-base batteries (e.g. nickel-cadmium and nickel-metal hydride batteries). The battery may be rechargeable via a wired or wireless connection. The power supply may, alternatively or in addition, include an external power outlet configured to charge the battery, bypass the battery, or to replace the battery altogether. The power supply may be or include another form of charge storage device such as a capacitor.

[0058] The aerosol generating system may be provided in the form of a replaceable pod and a device body. The aerosol-generating unit described above may be provided in the replaceable pod. The controller and battery may be provided in the device body.

[0059] In another aspect, the present disclosure provides a computer-readable medium comprising instructions that, when carried out by a computer, cause the computer to carry out any of the methods described herein.

[0060] The computer may, for example, be a control unit of any of the aerosol-generating apparatuses, devices or systems described herein.

[0061] The computer may, for example, be a remote computer that is communicatively connectable to any of the aerosol-generating apparatuses described herein.

[0062] The computer may, for example, be embodied as a distributed computing system including, for example, a control unit of any of the aerosol-generating apparatuses described herein and a remote computer that is communicatively connectable to any of the aerosol-generating apparatuses described herein, e.g., via a communications interface of the aerosol-generating apparatus.

[0063] In another aspect, the present disclosure provides electrical circuitry for an aerosol-generating system, the electrical circuitry being arranged to perform any of the methods described herein.

[0064] In embodiments, the electrical circuitry is implemented as one or more processors, which are configured to implement the disclosed steps, e.g. as the controller. The processors may execute program code stored on electronic memory and / or may execute logic, e.g. as a logic array, gate array, structured gate array.

[0065] As will be apparent from the present disclosure, the methods described herein may be carried out, or implemented, by a computer. The computer may, for example, be a processor installed in the aerosol-generating apparatus and configured to operate as a controller of the aerosol-generating apparatus. Alternatively, the computer may, for example, be a remote computer communicatively connectable to the aerosol-generating apparatus via a communications interface of the aerosol-generating apparatus. Alternatively, the computer may be embodied as a distributed computing environment, including for example, both a control unit installed in the aerosol-generating apparatus and a remote computer that is communicatively connectable to the control unit via a communications interface of the aerosol-generating apparatus.

[0066] Moreover, the acts described herein may be embodied using computer-executable instructions that can be implemented by one or more processors and / or stored on a computer-readable medium or media. The computer-executable instructions can include routines, sub-routines; programs; threads of execution, and / or the like. Still further, results of acts of the methods can be stored in a computer-readable medium, displayed on a display device, and / or the like.

[0067] The order of the operations of the methods described herein is exemplary, but the steps may be carried out in any suitable order, or simultaneously where appropriate. Additionally, steps may be added or substituted in, or individual steps may be deleted from any of the methods without departing from the scope of the subject matter described herein. Aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples without losing the effect sought.

[0068] Various functions described herein can be implemented in hardware, software, or any combination thereof. If implemented in software, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media may include, for example, computer-readable storage media. Computer-readable storage media may include volatile or non-volatile, removable or non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. A computer-readable storage media can be any available storage media that may be accessed by a computer. By way of example, and not limitation, such computer-readable storage media may comprise RAM, ROM, EEPROM, flash memory or other memory devices, CD-ROM or other optical disc storage, magnetic disc storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0069] Although illustrated as a local device it will be appreciated that the computing device may be located remotely and accessed via a network or other communication link (for example using a communication interface).

[0070] The term 'computer' is used herein to refer to any device with processing capability such that it can execute instructions. Those skilled in the art will realise that such processing capabilities are incorporated into many different devices and therefore the term 'computer' includes PCs, servers, mobile telephones, personal digital assistants and many other devices.

[0071] Those skilled in the art will realise that storage devices utilised to store program instructions can be distributed across a network. For example, a remote computer may store an example of the process described as software. A local or terminal computer may access the remote computer and download a part or all of the software to run the program. Alternatively, the local computer may download pieces of the software as needed or execute some software instructions at the local terminal and some at the remote computer (or computer network). Those skilled in the art will also realise that by utilising conventional techniques known to those skilled in the art that all, or a portion of the software instructions may be carried out by a dedicated circuit, such as a DSP, programmable logic array, or the like.

[0072] It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all the stated problems or those that have any or all of the stated benefits and advantages. Variants should be considered to be included into the scope of the invention.

[0073] 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 of the subject matter described herein in any way. Moreover, the above and / or following 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 figures.BRIEF DESCRIPTION OF THE FIGURES

[0074] Aspects, features and advantages of the present disclosure will become apparent from the following description of examples in reference to the appended figures in which like numerals denote like elements. Figure 1 shows an example of an aerosol-generating system; Figure 2 shows internal components of the aerosol-generating system; Figure 3 shows a method according to an aspect of the disclosure; Figure 4 shows a further method according to an aspect of the disclosure; Figure 5 shows a first example of a graph of duty cycle against time and a corresponding graph of heating system temperature against time; Figure 6 shows a second example of a graph of duty cycle against time and a corresponding graph of heating system temperature against time; Figure 7 shows a third example of a graph of duty cycle against time and a corresponding graph of heating system temperature against time; and Figure 8 shows an example of an ecosystem comprising an aerosol-generating system. DETAILED DESCRIPTION OF EMBODIMENTS

[0075] It is to be understood that the present disclosure, which includes the specification and claim(s), is not limited by specific construction details or process steps. Rather, it will be clear to those skilled in the art that the systems, apparatuses, and methods described herein can be embodied and practiced in various alternative ways without departing from the scope of the invention.

[0076] Unless defined otherwise, scientific and technical terms used herein have their meanings commonly understood by those skilled in the art and that known techniques and procedures may be performed according to conventional methods.

[0077] In the present disclosure, the terms "a" and "an" may mean "one", "one or more", "at least one", and "one or more than one" unless the context clearly indicates otherwise. Likewise, plural terms shall include the singular unless otherwise required by context.

[0078] In the present disclosure, the term "or" means an inclusive "and / or" unless explicitly indicated to refer to alternatives only or unless the alternatives are mutually exclusive.

[0079] In the present disclosure, the terms "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.

[0080] As used herein, the term "interface" relates to an element through which information can be transmitted, through which information can be received, or through which information can be both transmitted and received.

[0081] Examples of interfaces may include interfaces configured to convey information from the device to a user, namely output elements such as visual display elements, auditory elements, haptic elements, and / or interfaces configured to convey information from a user to the device, namely input elements such as buttons, dials, and sensory elements. Examples of sensory elements include touch screens, motion sensors, proximity sensors and auditory sensors.

[0082] As used herein, the term "haptic element" relates to an element configured to transmit tactile information to a user via the user's sense of touch. Typically, the user detects a haptic output from the haptic element at a predefined portion of the device. The user may detect the haptic output when contacting the haptic element directly or indirectly via one or more components of the device. The haptic output may comprise one or more of (e.g.) force, vibration, electro, ultrasonic, and thermal feedback that can be sensed by the user. The haptic element may be a mechanical actuator, piezoelectric actuator, thermal element, electromagnetic actuator, or ultrasonic actuator.

[0083] As used herein, the term "auditory element" relates to an element configured to generate a sound or auditory signal perceptible to a user. The term "auditory sensor" relates to a sensor configured to detect sound waves or auditory signals.

[0084] 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 cutouts to encode a bit, through which pins or a reader may be inserted).

[0085] 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 device, or distributed between the device and / or on one or more external devices in communication with the device, e.g. as part of the system.

[0086] 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. 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 device 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 an aerosol-generating system as disclosed herein, and may therefore be used synonymously with the term method.

[0087] As used herein, an "external device" (or "peripheral device") may include one or more electronic components external to an aerosol-generating system. Those components may be arranged at the same location as the device or remote from the device. 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.

[0088] 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 a system disclosed herein to perform a method as disclosed herein.

[0089] As used herein, a "communication resource" (or "communication interface") may refer to hardware and / or firmware for electronic information / data transfer. The communication resource may be configured for wired communication ("wired communication resources") or wireless communication ("wireless communication resource"). Wireless communication resources may include hardware to transmit and receive signals by radio and may include various protocol implementations e.g. the 802.11 standard described in the Institute of Electronics Engineers (IEEE) and Bluetooth ™< from the Bluetooth Special Interest Group of Kirkland Wash. Wired communication resources may include; Universal Serial Bus (USB); High-Definition Multimedia Interface (HDMI) or other protocol implementations. The system may include communication resources for wired or wireless communication with an external device.

[0090] As used herein, a "network" (or "computer network") may refer to a system for electronic information / data transfer between a plurality of apparatuses / devices. The network may, for example, include one or more networks of any type, which may include: a Public Land Mobile Network (PLMN); a telephone network (e.g. a Public Switched Telephone Network (PSTN) and / or a wireless network); a local area network (LAN); a metropolitan area network (MAN); a wide area network (WAN); an Internet Protocol Multimedia Subsystem (IMS) network; a private network; the Internet; an intranet.

[0091] It will be appreciated that any of the disclosed methods (or corresponding systems, programs, data carriers, etc.) may be carried out by either a host or client, depending on the specific implementation (i.e. the disclosed methods / systems 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.

[0092] Unless stated otherwise, the features of examples disclosed herein, and of the claims, may be integrated together in any suitable arrangement such that combinations of features are not limited by the described forms, particularly the form (e.g. numbering) of example(s), embodiment(s), or dependency of claim(s). This also applies to the phrase "in one example", "according to an example" and the like, which are merely a stylistic form of wording not to be construed as limiting the features to a separate embodiment. This is to say, a reference to 'an,' 'one,' or 'some' examples(s) may be a reference to any one or more, and / or all examples, or combination(s) thereof, disclosed. Also, similarly, reference to "the" example 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.

[0093] 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.

[0094] Figure 1 shows an example of an aerosol-generating system 1. In this example, the aerosol-generating system 1 is an electronic vapour product (EVP) configured to produce an aerosol from an aerosol-forming material 10 (e.g. a liquid or gel precursor), although it will be appreciated that the invention may be similarly applicable to a heat-not-burn product (HNB) configured to produce an aerosol from heating an aerosol-forming material (e.g. a solid precursor such as tobacco) to a temperature below its combustion temperature.

[0095] The term "aerosol-forming material" refers to a substrate or formulation capable of releasing volatile components that can form an aerosol, e.g. by releasing volatile compounds in the aerosol-forming material. An "aerosol" is a dispersion of solid particles and / or liquid droplets dispersed in a gas. The aerosol may be visible or invisible.

[0096] Figure 2 shows a schematic representation of the internal components of the aerosol-generating system 1. The aerosol-generating system 1 comprises an aerosol-generating unit 2 configured to generate an aerosol from an aerosol-forming material 10 held in a storage portion 3 of the aerosol-generating system 1 (implemented here as a "tank"). In this example, the aerosol-generating unit 2 is a heating system including a heating element 2a although it will be appreciated that an aerosol-generating unit comprising an ultrasonic element, atomiser or similar component may be provided.

[0097] The aerosol-forming material 10 may be referred to as "e-liquid". Typically, the aerosol-forming material 10 includes a base liquid and optionally nicotine and / or flavourings such that the resulting aerosol contains nicotine and / or flavourings.

[0098] The aerosol-generating system 1 includes a power source 4. In this example, the power source 4 includes a battery 4a configured to supply electrical energy to operate the aerosol-generating unit 2 and other components. The aerosol-generating system 1 may be powered, alternatively or in addition to the battery 4a, by an external power source. In an alternative example, the power source 4 may be omitted, e.g. an aerosol aerosol-generating unit implemented as an atomiser with flow expansion may not require a power supply.

[0099] The aerosol-generating system 1 includes an aerosol-delivery system 5 for delivery of the aerosol to a user. In this example, the aerosol-delivery system 5 comprises an air inlet 6, a mouthpiece 8, and an air passageway 7 extending therebetween via a region in proximity to the aerosol-generating unit 2.

[0100] The aerosol-generating unit 2 includes a wick 2b having at least one end that extends into the storage portion 3 and is configured to draw aerosol-forming material 10 out from the storage portion 3. In this example, the heating element 2a is in the form of a heating filament wrapped around a portion of the wick 2b. In this manner, the heating element 2a can heat up the aerosol-forming material 10 drawn out of the storage portion 3 by the wick 2b to produce the aerosol, which is then drawn through the air passageway 7 to the mouthpiece 8. In other examples, the heating element 2a may be a mesh heater, ceramic heater, or other means of generating heat. The heating element 2a may be part of an induction heater having a susceptor configured to produce heat when penetrated by an alternating magnetic field.

[0101] The aerosol-generating system 1 may be a two-part construction comprising a device body 20 and an article 30 (alternatively referred to as a "pod" or "cartomizer") configured to be releasably connected / disconnected by an end user. The device body 20 and article 30 are each configured to house respective components of the aerosol-generating system 1.

[0102] In some examples, the article 30 may be configured to be disposed of upon depletion of aerosol-forming material 10 from the storage portion, in which case the article 30 may referred to as a "consumable". Alternatively, the article 30 may be configured for reuse, such that it is configured to be refillable upon depletion of the aerosol-forming material 10 from the storage portion.

[0103] In this example, the device body 20 comprises the power source 4, and the article 30 comprises the aerosol-generating unit 2 and storage portion 3, although it will be appreciated that the device body 20 and article 30 may house any respective set of components. The device body 20 and article 30 are configured to physically interlock to secure the article 30 relative to the device body 20.

[0104] Upon connection, electrical connectors 40 of the device body 20 and article 30 may establish an electrical connection between the device body 20 and the article 30. In this way, electrical power can be supplied from the power source 4 to the aerosol-generating unit 2 (or other components of the article 30) without the article 30 needing to have its own power supply.

[0105] The device body 20 may include any one or more of electrical circuitry, a memory, a wireless interface, and one or more other components. The device body 20 may include a printed circuit board (PCB) on which components of the electrical circuitry, memory, wireless interface, and other components may be mounted.

[0106] The electrical circuitry may include a processing resource for controlling one or more operations of the body 20 and article 30, e.g. based on instructions stored in the memory. The wireless interface may be configured to communicate wirelessly with an external (e.g. mobile) device, e.g. via Bluetooth. The other component(s) may include one or more user interface devices configured to convey information to a user, a pressure sensor 15, and / or a charging port 18 (see e.g. figure 2).

[0107] The aerosol-generating system 1 may comprise one or more input and / or output elements. In this example, the aerosol-generating system 1 includes an input element in the form of a pressure sensor 15 arranged to detect a "puff" of the user, and particularly the resultant change in air pressure, i.e. a vacuum pressure generated by the user. Alternatively, or in addition, the aerosol-generating system 1 may include other means of detecting airflow, such as a flowmeter or microphone. The user can thereby activate the aerosol-generating unit 2 when inhaling through the mouthpiece 8. The aerosol-generating unit 2 creates an aerosol which is carried by the flow through the air passageway 7 and out of the mouthpiece 8.

[0108] The input and / or output elements may form part of a user interface (UI) of the aerosol-generating system 1. For instance, figure 2 shows an output element in the form of a light (e.g. an LED) 17. The light 17 is configured to convey information to the user regarding the state of the system 1. It will be appreciated that the input element(s) may be provided in various forms, such as touch screens, switches, and sensors, and the output element(s) may be provided in various forms, such as display screens, speakers, or a haptic output generated by a vibration generator.

[0109] Figure 3 shows a method 100 for determining whether insufficient aerosol precursor is present at an aerosol-generating unit 2 of an aerosol-generating system 1. In particular, the method 100 described herein may be a method for determining whether insufficient aerosol precursor, or aerosol -forming material 10, is present at the wick 2b of the aerosol-generating unit 2.

[0110] The method may begin in step 110 by receiving an activation signal for activating the aerosol-generating unit 2. The activation signal may be generated by the pressure sensor 15 in response to a "puff" of the user.

[0111] From step 110 the method 100 may progress to step A, which is described in further detail below with respect to Figure 4. Otherwise, the method progresses to step 120, wherein, in response to receiving the activation signal in step 110, it is determined that an aerosol generation session has started at a first point in time. The aerosol generation session may last as long as the user is inhaling and a "puff" is detected by the pressure sensor 15.

[0112] The method 100 progresses to step 130 in which a driving signal is generated to cause the aerosol-generating unit 2 to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle. The driving signal may cause the heating element 2a to heat the aerosol precursor, or aerosol - forming material 10, in the wick 2b in order to generate an aerosol.

[0113] The driving signal is generated with an initial duty cycle; however, the duty cycle of the driving signal may be controlled using PWM to vary the duty cycle over the course of the aerosol generation session. The duty cycle may be varied based on a parameter of the aerosol-generating unit 2.

[0114] In particular, in step 140, the temperature of the heating element 2a may be monitored and the duty cycle of the driving signal may be adjusted in step 150 based on the temperature of the heating element 2a. As outlined in further detail below with respect to Figures 5 to 7, the duty cycle of the driving signal may be reduced as the temperature of the heating element 2a increases.

[0115] In step 160, the duty cycle of the driving signal, and any variation in the duty cycle of the driving signal, is monitored during the aerosol generation session. The method progresses to step 170 when it is determined that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold (e.g., below 20% or below 10%), which marks a second point in time after the first point in time.

[0116] The method 100 then progresses to step 180 where the time period between the first point in time (i.e., when the aerosol generation session began) and the second point in time (i.e., when the duty cycle fell below the predetermined threshold) is compared to a reference time period (e.g., which may be a time period of one second or less). If the time period is less than the reference time period, the method progresses to step 190, in which it is determined that insufficient aerosol precursor is present at the aerosol-generating unit 2. The aerosol-generating unit 2 may be deactivated in response to the determination in step 190. If the time period is greater than, or equal to, the reference time period, the aerosol-generating system may continue to operate as normal.

[0117] Figure 4 shows a method 200 for controlling an aerosol-generating unit of an aerosol-generating system. The method begins in step A, which is preceding by step 110 in the method 100 shown in Figure 3.

[0118] In step 210, it is determined that a new aerosol generation session has started. Determining that a new aerosol generation session has started may comprise the same steps as determining that an aerosol generation session has begun at a first point in time in step 120 outlined above with respect to Figure 3.

[0119] The method 200 may then progress to step 220 where an elapsed time between the new aerosol generation session and a previous aerosol generation session, immediately preceding the new aerosol generation session, is obtained.

[0120] In step 230 the elapsed time obtained in step 220 is compared to a predetermined elapsed time threshold. If the elapsed time is greater than, or equal to, the predetermined elapsed time threshold (e.g., two seconds or more), the method progresses to step B, and returns to the method 100 for determining whether insufficient aerosol precursor is present at the aerosol-generating unit 2 as described above with reference to Figure 3.

[0121] If in step 230 it is found that the elapsed time is less than the predetermined elapsed time threshold, the method may progress to step 240 in which an aerosol is generated using the aerosol-generating unit 2.

[0122] Figure 5 shows a first example of a graph 300 of duty cycle against time and a corresponding graph 350 of heating system temperature against time. Figure 6 shows a second example of a graph 400 of duty cycle against time and a corresponding graph 450 of heating system temperature against time.

[0123] Figure 7 shows a third example of a graph 500 of duty cycle against time and a corresponding graph 550 of heating system temperature against time.

[0124] In each of the examples in Figures 5 to 7, it has been assumed that the heating system has the same initial starting temperature. Accordingly, the primary variable between the three examples illustrated in Figures 5 to 7 is the amount of aerosol precursor, i.e., aerosol forming material 10, present at the aerosol-generating unit 2, i.e., at the wick 2b.

[0125] The example shown in Figure 5 illustrates an example where the wick 2b of the aerosol-generating unit 2 is fully saturated with aerosol precursor.

[0126] In the example shown in Figure 5, the graph 300 of duty cycle against time shows a driving signal across an aerosol generation session, which has been divided into five periods 310a to 310e. Each period has an associated duty cycle 320a to 320e. The driving signal begins when the aerosol generation session is determined to have started, as described above, at the first point in time, t 1 .

[0127] The corresponding graph 350 of temperature against time shows a plot 360 of the change in temperature of the heating element 2a of the aerosol-generating unit over the course of the aerosol generation session in response to the driving signal illustrated in graph 300.

[0128] As shown in Figure 5, the rate of change of the temperature of the heating element 2a is relatively low when the wick 2b is saturated with aerosol precursor. Accordingly, in the first three periods 310a, 310b and 310c of the aerosol generation session, the duty cycles 320a, 320b and 320c are relatively high (e.g., 80%).

[0129] As the temperature of the heating element 2a approaches the target temperature 370 for aerosol generation, the duty cycles 320d and 320e in periods 310d and 310e are gradually reduced in order to slow the rise in temperature of the heating element 2a.

[0130] In the example shown in Figure 5, the duty cycle does not fall below the predetermined duty cycle threshold, and so there is no determination that insufficient aerosol precursor is present at the aerosol generating unit 2.

[0131] The example shown in Figure 6 illustrates an example where sufficient aerosol precursor for aerosol generation is present at the wick 2b of the aerosol-generating unit 2, but the wick is not saturated, for example because the aerosol-generating system contains less than the full amount of aerosol precursor.

[0132] In the example shown in Figure 6, the graph 400 of duty cycle against time shows a driving signal across an aerosol generation session, which has been divided into five periods 410a to 410e. Each period has an associated duty cycle 420a to 420e. The driving signal begins when the aerosol generation session is determined to have started, as described above, at the first point in time, t 1 .

[0133] The corresponding graph 450 of temperature against time shows a plot 460 of the change in temperature of the heating element 2a of the aerosol-generating unit over the course of the aerosol generation session in response to the driving signal illustrated in graph 400.

[0134] As shown in Figure 6, the rate of change of the temperature of the heating element 2a is higher when sufficient aerosol precursor is present at the wick 2b, but the wick 2b is not fully saturated, compared to the example shown in Figure 5. Accordingly, in the first period 410a of the aerosol generation session, the duty cycle 420a is relatively high (e.g., 80%), but in the second period 410b and the third period 410c the duty cycles 420b and 420c are gradually reduced due to the more rapid rise in temperature of the heating element 2a.

[0135] By the beginning of the fourth period 410d, the duty cycle has fall below the predetermined duty cycle threshold 430 (e.g., below 20%) and the temperature of the heating element 2a is being maintained around the target temperature 470. The duty cycle is determined to have fallen below the predetermined duty cycle threshold 430 at a second point in time, t 2 .

[0136] The time period, Δt, between the first point in time, t 1 , and the second point in time, t 2 , is compared to a reference time period in order to determine whether insufficient aerosol precursor is present at the wick 2b. In the example shown in Figure 6, the time period, Δt, exceeds the reference time period because sufficient aerosol precursor is present at the aerosol-generating unit 2.

[0137] The example shown in Figure 7 illustrates an example where insufficient aerosol precursor for aerosol generation is present at the wick 2b of the aerosol-generating unit 2, for example because the aerosol-generating system contains little to no aerosol precursor.

[0138] In the example shown in Figure 7, the graph 500 of duty cycle against time shows a driving signal across an aerosol generation session, which has been divided into five periods 510a to 510e. Each period has an associated duty cycle 520a to 520e. The driving signal begins when the aerosol generation session is determined to have started, as described above, at the first point in time, t 1 .

[0139] The corresponding graph 550 of temperature against time shows a plot 560 of the change in temperature of the heating element 2a of the aerosol-generating unit over the course of the aerosol generation session in response to the driving signal illustrated in graph 500.

[0140] As shown in Figure 7, the rate of change of the temperature of the heating element 2a is higher when insufficient aerosol precursor is present at the wick 2b, compared to the examples shown in Figures 5 and 6. Accordingly, in the first period 510a of the aerosol generation session, the duty cycle 520a is relatively low (e.g., 50%), but in the second period 510b the duty cycle 520b has already fallen below the predetermined duty cycle threshold 530 (e.g., below 20%) due to the rapid rise in temperature of the heating element 2a. The duty cycle is determined to have fallen below the predetermined duty cycle threshold 530 at a second point in time, t 2 .

[0141] The time period, Δt, between the first point in time, t 1 , and the second point in time, t 2 , is compared to a reference time period in order to determine whether insufficient aerosol precursor is present at the wick 2b. In the example shown in Figure 7, the time period, Δt, is less than the reference time period because insufficient aerosol precursor is present at the aerosol-generating unit 2.

[0142] In the example shown in Figure 7, the determination that insufficient aerosol precursor is present at the wick 2b may also have been made based on the rate of change of duty cycle in response to the rapid rise in temperature of the heating element 2a, for example within the first period 510a.

[0143] Figure 8 shows an example of an ecosystem 50 comprising an aerosol-generating system 1, a mobile device 52, an application server 54, and a charging station 56.

[0144] In this example, the aerosol-generating system 1 is configured to communicate wirelessly, e.g. via Bluetooth ™< , with an application (or "app") installed on the mobile device 52, via a wireless interface included in the aerosol-generating system 1 and via a wireless interface included in the mobile device 52. The mobile device 52 may be a mobile phone, for example. The application on the mobile device 52 may be configured to communicate with the application server 54, via a network 58. The application server 54 may utilise cloud storage, for example.

[0145] The network 58 may include a cellular network and / or the internet.

[0146] In other examples, the aerosol-generating system 1 may be configured to communicate with the application server 54 via a connection that does not involve the mobile device 52, e.g. via a narrowband internet of things ("NB-IoT") or satellite connection. In some examples, the mobile device 52 may be omitted from the ecosystem 50.

[0147] A skilled person would readily appreciate that the mobile device 52 may be configured to communicate via the network 58 according to various communication channels, for instance a wireless communication channel such as via a cellular network (e.g. according to a standard protocol, such as 3G or 4G) or via a WiFi network.

[0148] The app installed on the mobile device 52 and the application server 54 may be configured to assist a user with managing the aerosol-generating system 1, based on information communicated between the aerosol-generating system 1 and the app, information communicated directly between the aerosol-generating system 1 and the application server 54, and / or information communicated between the app and the application server 54.

[0149] The charging station 56 (if present) may be configured to charge (and optionally communicate with) the aerosol-generating system 1, via a charging port 18 on the aerosol-generating system 1. The charging port 18 on the aerosol-generating system 1 may be a USB port, for example, which may allow the aerosol-generating system 1 to be charged by any USB-compatible device capable of delivering power to the aerosol-generating system 1 via a suitable USB cable (in this case the USB-compatible device would be acting as the charging station 56). Alternatively, the charging station could be a docking station configured to dock with the aerosol-generating system 1 and charge the aerosol-generating system 1 via the charging port 18 on the aerosol-generating system 1.

Examples

Embodiment Construction

[0075]It is to be understood that the present disclosure, which includes the specification and claim(s), is not limited by specific construction details or process steps. Rather, it will be clear to those skilled in the art that the systems, apparatuses, and methods described herein can be embodied and practiced in various alternative ways without departing from the scope of the invention.

[0076]Unless defined otherwise, scientific and technical terms used herein have their meanings commonly understood by those skilled in the art and that known techniques and procedures may be performed according to conventional methods.

[0077]In the present disclosure, the terms "a" and "an" may mean "one", "one or more", "at least one", and "one or more than one" unless the context clearly indicates otherwise. Likewise, plural terms shall include the singular unless otherwise required by context.

[0078]In the present disclosure, the term "or" means an inclusive "and / or" unless explicitly indicated to...

Claims

1. A method for determining whether insufficient aerosol precursor is present at an aerosol-generating unit of an aerosol-generating system, the method comprising: determining that an aerosol generation session has started at a first point in time; generating a driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle; monitoring the duty cycle of the driving signal during the aerosol generation session; determining that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time; comparing a time period between the first point in time and the second point in time to a reference time period; and if the time period is less than the reference time period, determining that insufficient aerosol precursor is present at the aerosol-generating unit.

2. The method claimed in claim 1, wherein the method further comprises: monitoring a parameter of the aerosol-generating unit during the aerosol generation session; and adjusting the duty cycle based on the parameter.

3. The method claimed in claim 2, wherein the aerosol-generating unit comprises a heating system for heating the aerosol precursor to generate an aerosol, and wherein the parameter comprises a temperature of the heating system.

4. The method claimed in any preceding claim, wherein the method further comprises: determining a rate of change of the duty cycle of the driving signal during the aerosol generation session; and if the rate of change of the duty cycle exceeds a predetermined rate of change threshold, determining that insufficient aerosol precursor is present at the aerosol-generating unit.

5. The method claimed in any preceding claim, wherein the predetermined duty cycle threshold is less than 20%.

6. The method claimed in any preceding claim, wherein the reference time period is less than one second.

7. The method claimed in any preceding claim, wherein determining that the aerosol generation session has started comprises: receiving an activation signal for activating the aerosol-generating unit; and determining that the aerosol-generating session has started based on the activation signal.

8. A method for controlling an aerosol-generating unit of an aerosol-generating system, the method comprising: determining that a new aerosol generation session has started; obtaining an elapsed time between the new aerosol generation session and a previous aerosol generation session; comparing the elapsed time to a predetermined elapsed time threshold; and if the elapsed time is greater than, or equal to, the predetermined elapsed time threshold, determining whether insufficient aerosol precursor is present at an aerosol-generating unit of an aerosol-generating system according to the methods of any of claims 1 to 7; and if the elapsed time is less than the predetermined elapsed time threshold, generating an aerosol using the aerosol-generating unit.

9. The method claimed in claim 8, wherein the elapsed time period is greater than two seconds.

10. An aerosol-generating system, the aerosol-generating system comprising: an aerosol-generating unit for generating an aerosol from an aerosol precursor; and a controller adapted to: determine that an aerosol generation session has started at a first point in time; generate a driving signal to cause the aerosol-generating unit to generate an aerosol from the aerosol precursor, the driving signal having a duty cycle; monitor the duty cycle of the driving signal during the aerosol generation session; determine that the duty cycle of the driving signal has fallen below a predetermined duty cycle threshold at a second point in time; compare a time period between the first point in time and the second point in time to a reference time period; and if the time period is less than the reference time period, determine that insufficient aerosol precursor is present at the aerosol-generating unit.

11. The aerosol-generating system claimed in claim 10, wherein the aerosol-generating unit comprises a heating system, and wherein the controller is further adapted to: monitor a parameter of the aerosol-generating unit during the aerosol generation session, wherein the parameter comprises a temperature of the heating system; and adjust the duty cycle based on the parameter.

12. The aerosol-generating system claimed in any of claims 10 to 11, wherein the controller is further adapted to: determine a rate of change of the duty cycle of the driving signal during the aerosol generation session; and if the rate of change of the duty cycle exceeds a predetermined rate of change threshold, determine that insufficient aerosol precursor is present at the aerosol-generating unit.

13. The aerosol-generating system claimed in any of claims 10 to 12, wherein the aerosol precursor is a liquid or a gel.

14. A computer-readable medium comprising instructions that, when carried out by a computer, cause the computer to carry out the method of any of claims 1 to 9.

15. Electrical circuitry for an aerosol-generating system, the electrical circuitry being arranged to perform the method of any of claims 1 to 9.

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