An aerosol generating device

Abstract

An aerosol generating device (10) is described. The aerosol generating device (10) is adapted to generate an aerosol during an operating session in which aerosol generating material is heated. The aerosol generating device (10) includes an energy storage device (22) and a charging circuit (40) that is adapted to charge the energy storage device (22). At least one of a controller (38) of the aerosol generating device (10) and the charging circuit (40) is adapted to terminate charging of the energy storage device (22) when the remaining capacity or state of charge of the energy storage device (22) reaches a threshold value that is less than the capacity or state of charge of the energy storage device (22) when fully charged. The threshold value is dynamically set based on the amount of energy of the energy storage device (22) consumed in a previous operating session and / or the degradation of the energy storage device (22).

Description

[0001] AN AEROSOL GENERATING DEVICE

[0002] Technical Field

[0003] The present disclosure relates generally to an aerosol generating device, and in particular to a device that is configured to heat aerosol generating material to generate an aerosol for inhalation by a user. The aerosol generating device may be adapted to generate an aerosol during an operating session (e.g., a vaping session) in which the aerosol generating material is heated by a heater or heater assembly.

[0004] The present disclosure is particularly applicable to a portable (hand-held) aerosol generating device. The aerosol generating material may be part of an aerosol generating article that may be received in the device in use.

[0005] Technical Background

[0006] Devices which heat, rather than bum, an aerosol generating material to produce an aerosol for inhalation have become popular with consumers in recent years. A commonly available reduced-risk or modified- risk device is the heated material aerosol generating device, or so-called heat-not-bum device. Devices of this type generate an aerosol or vapour by heating an aerosol generating material to a temperature typically in the range 150°C to 300°C, and in some cases as high as 350°C. This temperature range is quite low compared to an ordinary cigarette. Heating the aerosol generating material to a temperature within this range, without burning or combusting the aerosol generating material, generates a vapour which typically cools and condenses to form an aerosol for inhalation by a user of the device.

[0007] The aerosol generating material may be a solid. For example, the aerosol generating article may include a solid or semi-solid substrate of plant derived material, such as tobacco. The aerosol generating device may include a heater and an energy storage device such as a battery. The battery may be a rechargeable battery that may be charged from an external power source by a charging assembly of the aerosol generating device. During an operating session of the aerosol generating device (e.g., a vaping session) the battery may supply power to the heater for heating the aerosol generating material to generate an aerosol.

[0008] A fully charged battery will be able to provide enough power for the user to complete a particular number of operating sessions before it needs to be recharged. Typically, a fully charged battery will allow a user to complete several operating sessions before it needs to be recharged. In other words, the battery does not normally need to be recharged after each operating session. The number of operating sessions that may be completed before the battery needs to be recharged will normally decrease as the battery ages. For example, with a new battery the user may be able to complete twenty operating sessions before the battery needs to be recharged. But this may gradually decrease as the battery ages so that eventually, even when the battery is fully charged, the user may only be able to complete twenty operating sessions, or fewer, before the battery needs to be recharged. This reduction in battery performance will often be

[0009] P51781WO-6677 noticed by the user. In particular, the user may notice that the battery of the aerosol generating device needs to be recharged more often as the battery ages. In some cases, there may be a more significant decrease in the number of operating sessions that may be completed with a single charge during the first few months of the battery. This is preferably avoided because the user may not be completely satisfied with the battery performance, despite the battery being relatively new. A manufacturer of aerosol generating devices may also use batteries supplied by different suppliers, i.e., more than one battery model. The same type of aerosol generating device may therefore have different charging capacities and different battery performance. For example, two users may use the same type of aerosol generating device, but if these devices have different battery models, a first user may need to charge their aerosol generating device more frequently than the second user even when the batteries are new. This is also preferably avoided because the first user may not be completely satisfied with their aerosol generating device because of the difference in battery performance.

[0010] There is therefore a need for an aerosol generating device that avoids these problems by terminating charging before the battery is fully charged. This may allow a consistent number of operating sessions to be completed before the battery needs to be recharged even as the battery ages. It also means that aerosol generating devices of the same type may allow the same number of operating sessions to be completed with a “fully charged” battery even if different battery models with different charging capacities are used by the manufacturer. The aim is to keep the number of operating sessions that may be completed by a “fully charged” battery to be constant for a significant proportion of the expected lifetime of the battery. It will be understood that the term “fully charged” may therefore refer to a battery that has been charged by a terminated charging sequence even though its charge is less than the maximum charge. If a charging sequence is terminated by the controller or the charging circuit of the aerosol generating device, the user will normally perceive this to mean that the battery is “fully charged” even if its charge is less than the maximum charge (e.g., even if the state of charge (SoC) is less than 100%). In the following description, it will be clear from the context if the term “fully charged” refers to an energy storage device that has been charged so that its current charge is equal to the maximum charge that may be provided by the energy storage device, or to an energy storage device that a user may perceive to be “fully charged” even though its charge is less than the maximum charge when the charging sequence is terminated.

[0011] Summary of the Disclosure

[0012] According to a first aspect of the present disclosure, there is provided an aerosol generating device adapted to generate an aerosol during an operating session in which aerosol generating material is heated, the aerosol generating device comprising: an energy storage device (e.g., a rechargeable battery such as a Li-ion battery); a charging circuit adapted to charge the energy storage device; and a controller (e.g., a microcontroller unit (or MCU));

[0013] P51781WO-6677 wherein at least one of the controller and the charging circuit (and an optional protection circuit) is adapted to terminate charging of the energy storage device when the remaining capacity or state of charge of the energy storage device reaches a threshold value that is less than the capacity or state of charge (SoC) of the energy storage device when fully charged (e.g., where the charge is less than the maximum charge or where SoC is less than 100%); and wherein the threshold value is dynamically set based on the amount of energy of the energy storage device consumed in a previous operating session and / or the degradation (e.g., state of health (SoH)) of the energy storage device.

[0014] The controller may be adapted to output a disable signal to the charging circuit when the remaining capacity or SoC of the energy storage device reaches the threshold value. As used herein, the term “SoC” describes the difference between a fully charged energy storage device and the same energy storage device in use, and may be defined as the ratio of the remaining charge in the energy storage device divided by the maximum charge that may be provided by the energy storage device. For a new energy storage device, the maximum charge is normally equal to the rated capacity of the energy storage device provided by the manufacturer. As the energy storage device ages, the maximum charge will decrease and will be less than the rated capacity provided by the manufacturer. If the energy storage device is fully charged the SoC is 100%. If the energy storage device is fully discharged the SoC is 0%. The remaining charge of the energy storage device may be determined or estimated in any suitable way, e.g., using coulomb counting, which relies on the integration of the current drawn from and supplied to the energy storage device over time, or by using other measurements of other electrical parameters of the energy storage device, for example.

[0015] Degradation of the energy storage device may be indicated by the SoH of the energy storage device. As used herein, the term “SoH” describes the difference between the current energy storage device and the same energy storage device when new, and may be defined as the ratio of the maximum charge of the aged energy storage device divided by the rated capacity of the energy storage device provided by the manufacturer (i.e., the maximum charge of the energy storage device when new).

[0016] Terminating charging before the energy storage device is fully charged, e.g., when the remaining capacity or SoC of the energy storage device reaches the threshold value, may allow a consistent number of operating sessions to be completed before the energy storage device needs to be recharged even as the energy storage device ages. For example, it may be that the user of an aerosol generating device will be able to complete twenty operating sessions when a new energy storage device is “fully charged” - i.e., charged to the threshold value - and that this will remain constant for a significant proportion of the expected lifetime of the energy storage device. It will be understood that if the charging was not limited to the threshold level, if a new energy storage device was fully charged to its maximum charge it may be possible for the user to complete more than twenty operating sessions, e.g., twenty-four or twenty-five operating sessions, before the energy storage device needs to be recharged. But this would then decrease

[0017] P51781WO-6677 as the energy storage device ages. Put another way, by terminating the charging at the lower threshold value, the aerosol generating device is effectively limiting the number of charging sessions that may be completed before the energy storage device needs to be recharged. But the user is being provided with a more consistent experience because the number of charging sessions will remain constant even as the energy storage device ages and will only start to decrease towards the end of the expected lifetime of the energy storage device. The user may therefore know more precisely after how many operating sessions the energy storage device will likely need to be re-charged. It also means that aerosol generating devices of the same type will allow the same number of operating sessions to be completed with an energy storage device that is “fully charged” - i.e., charged to the threshold level - even if different energy storage device models with different charging capacities are used by the manufacturer. In general, charging the energy storage device until it is fully charged, or keeping it at a fully charged state for a long period of time, may accelerate the degradation of the energy storage device. Terminating charging before the energy storage device is fully charged to its maximum charge (i.e., before SoC reaches 100%) may therefore also be beneficial by delaying the degradation of the energy storage device.

[0018] A dynamically set threshold value is used instead of a fixed threshold value. The threshold value is set based on the amount of energy of the energy storage device consumed in a previous operating session and / or the degradation of the energy storage device as it ages. For example, it may be expected that a required amount of energy for the next operating session will be substantially the same as the amount of energy consumed during a previous operating session (or a moving average of two or more previous operating sessions). This means that the threshold value may be set to be equal to the product of the amount of energy consumed in a previous operating session and the consistent number of operating sessions (e.g., twenty) after which the energy storage device will need to be recharged. A calculated threshold value based on remaining capacity may be converted into other parameters such as SoC or voltage, for example. A buffer that represents an amount of energy that may be consumed by other components of the aerosol generating device or by self-discharging of the energy storage device may be added to the calculated threshold value. If the user starts to use the aerosol generating device in a different way, which may in turn mean that the amount of energy consumed by the energy storage device changes, the threshold value may be adjusted accordingly. For example, the user may start to take more frequent or longer puffs during an operating session. This may mean that the amount of energy that is consumed by the energy storage device during an operating session increases because additional heating of the aerosol generating article is needed. In this case, the threshold value for the subsequent charging sequence may be increased, but the number of operating sessions after which the energy storage device will need to be recharged may stay the same. Using a higher threshold value means that the energy storage device will have a higher charge (or higher SoC) when the charging sequence is terminated by the controller or the charging circuit. On the other hand, if the amount of energy that is consumed by the energy storage device during an operating session decreases, the threshold value for the subsequent charging sequence may be decreased so that the energy storage device will have a lower charge (or lower SoC) when the charging sequence is terminated by the controller or the charging circuit.

[0019] P51781WO-6677 To simplify the calculation of the threshold value that needs to be carried out by the aerosol generating device (e.g., by the controller), the threshold value may be defined in advance as a function or a look-up table based on the degradation of the energy storage device, for example. Such a function or look-up table may be designed by referring to several measurement results so that it will be applicable for many different users or different functions or look-up tables may be used depending on a user profile or how the user uses the aerosol generating device. The threshold value may therefore be set by using the function or look-up table.

[0020] The threshold value may be based on the amount of energy consumed during a previous operating session (or a moving average of two or more previous operating sessions) and the degradation of the energy storage device. For example, after obtaining a threshold value using a function or look-up table based on the degradation of the energy storage device, the threshold value may be adjusted based on the amount of energy consumed during a previous operating session (or the moving average of two or more previous operating sessions) or vice versa.

[0021] There are several ways in which charging of the energy storage device may be terminated when the remaining capacity or SoC reaches the threshold value. However, outputting the disable signal to the charging circuit from the controller will typically be the most reliable and stable, unless there is a problem with the controller (e.g., the controller freezes).

[0022] The aerosol generating device may further comprise a digital to analog converter adapted to output a buffer voltage, and a non- inverting adder circuit adapted to sum the buffer voltage and an output voltage of the energy storage device and to output the sum of the buffer voltage and the output voltage of the energy storage device to an energy storage device voltage sensing terminal (e.g., a battery voltage sensing terminal) of the charging circuit. The digital to analog converter may be implemented as part of an integrated circuit (IC). The controller is adapted to adjust the buffer voltage based on the threshold value.

[0023] The charging circuit may be provided as a commercially-available IC - e.g., a charging IC. Such a charging IC is advantageous because it allows the aerosol generating device to carry out or perform a charging sequence without the need for the manufacturer to design its own charging function or algorithm. This means that the charging IC will often be optimised to complete the charging sequence only when the energy storage device is fully charged, and it may not be easy to modify the charging sequence so that charging is terminated early. Instead of modifying the charging sequence of the charging IC, it is possible to modify a signal inputted to the charging IC and / or a peripheral circuit of the charging IC. For example, the charging IC may recognise the progress of the charging sequence based on an output voltage of the energy storage device. The digital to analog converter and the non-inverting adder circuit may provide a dummy voltage signal that is higher than the output voltage of the energy storage device to the energy storage device voltage sensing terminal of the charging IC. As a result, the charging IC

[0024] P51781WO-6677 may recognise that the charging sequence has progressed further than would be the case if the output voltage of the energy storage device was inputted to the energy storage device voltage sensing terminal. The charging IC may therefore terminate the charging sequence before the energy storage device is fully charged. The magnitude of the buffer voltage outputted by the digital to analog converter may be adjusted or varied to determine when the charging sequence is terminated by the charging IC. Put another way, the magnitude of the buffer voltage outputted by the digital to analog converter may be adjusted or varied so that the charging is terminated when the remaining capacity or SoC of the energy storage device reaches a threshold value that is dynamically set based on the amount of energy previously consumed and / or the degradation of the energy storage device.

[0025] The non-inverting adder circuit may comprise an operational amplifier with a positive power supply terminal. The aerosol generating device may further comprise a boost converter adapted to output a boosted voltage, and a heater adapted to heat the aerosol generating material. The positive power supply terminal of the operational amplifier and the heater may be electrically connected to the boost converter. The maximum output voltage of an operational amplifier may correspond to the electrical potential difference between its positive and negative power supply terminals. If it is necessary for the operational amplifier to output a voltage that is higher than the output voltage of the energy storage device, it may be necessary to use a boost converter (e.g., a switching regulator) to convert the output voltage of the energy storage device to a higher voltage that may be inputted to the positive power supply terminal of the operational amplifier. It will be understood that adding a boost converter (and often a corresponding inductor) will increase the complexity of the circuit and will also take up a relatively large surface area of the printed circuit board on which the various circuit components are mounted. However, if the aerosol generating device includes a heater, it may be beneficial to use the same boost converter to supply power to both the heater and the operational amplifier. This may improve heating efficiency and provides efficient use of the available surface area of the printed circuit board.

[0026] The aerosol generating device may further comprise a digital to analog converter adapted to output a voltage to an energy storage device voltage sensing terminal (e.g., a battery voltage sensing terminal) of the charging circuit. The digital to analog converter may be implemented as part of an IC. The controller may be adapted to adjust the output voltage of the digital to analog converter based on one or both of: (a) the threshold value, and (b) the remaining capacity or SoC of the energy storage device. This may result in simplification of the circuit. Compared to the combination of the digital to analog converter and the non- inverting adder circuit described above, only the digital to analog converter is required to provide a dummy voltage to the energy storage device voltage sensing terminal of the charging circuit.

[0027] The controller may be adapted to receive the remaining capacity or SoC of the energy storage device through a first communication line. The controller may be adapted to adjust the output voltage of the digital to analog converter through a second communication line that is isolated from the first communication line. The first communication line that transmits the remaining capacity or SoC may

[0028] P51781WO-6677 become busy, particularly during charging of the energy storage device. For example, at some times during the charging sequence, the remaining capacity or SoC may change frequently and so the first communication line will become very busy - i.e., more signals will be transmitted to the controller along the first communication line. By isolating the second communication line from the first communication line, the load on the first communication line is reduced because the signals for adjusting the output voltage of the digital to analog converter are transmitted through a separate communication line. This means that the controller will receive the latest value of the remaining capacity or SoC of the energy storage device and communicate with the digital to analog converter without undue delay.

[0029] The aerosol generating device may further comprise a variable resistor electrically connected to a termination current threshold terminal of the charging circuit. The controller may be adapted to adjust the resistance value of the variable resistor based on the threshold value. A commercially-available charging IC may use a charging sequence with a constant current (or “CC”) mode and a constant voltage (or “C V”) mode - see below. In the constant voltage mode, charging is considered to be completed when a charging current reaches or falls below a termination current threshold while a constant voltage is applied across the energy storage device. A termination current threshold may be set or adjusted based on a resistance value of a resistor connected to the termination current threshold terminal of the charging circuit (e.g., the charging IC). Accordingly, using a variable resistor that is electrically connected to the termination current threshold terminal may be beneficial in allowing the termination current threshold to be easily varied. This may make it easier to change when the normal charging sequence is completed.

[0030] The aerosol generating device may further comprise a variable resistor electrically connected between an output charging terminal of the charging circuit and the energy storage device. The controller may be adapted to adjust the resistance value of the variable resistor based on the threshold value. The controller may be further adapted to adjust the resistance value of the variable resistor based on an internal resistance of the energy storage device. Due to the internal resistance of the energy storage device, the energy storage device and the variable resistor may form a voltage divider circuit. A charging voltage outputted from the output charging terminal of the charging circuit may be divided by this voltage divider circuit so that a lower voltage is applied to the energy storage device. If a lower charging voltage is applied to the energy storage device, charging may be terminated early - i.e., before the energy storage device is fully charged. In addition, if the controller may adjust the resistance value of the variable resistor, the termination time of the charging sequence may be more flexibly adjusted. This may be useful if a charging IC does not have an energy storage device voltage sensing terminal. In fact, some commercially-available charging ICs do not have an energy storage device voltage sensing terminal to reduce size and / or cost.

[0031] The aerosol generating device may further comprise a protection circuit adapted to terminate charging of the energy storage device when a voltage inputted to a voltage sensing terminal of the protection circuit is greater than or equal to an over-voltage protection threshold. A voltage that is greater than the

[0032] P51781WO-6677 output voltage of the energy storage device may be adapted to be provided to the voltage sensing terminal. In general, the protection circuit may be implemented as an IC and may protect the energy storage device - i.e., so that the energy storage device does not fall into an over-voltage (or over-charged) state. The over-voltage protection threshold may be set so that it is higher than a fully charged voltage of the energy storage device so that the over-voltage protection is only carried out or performed under limited circumstances. If the voltage that is provided to the voltage sensing terminal is greater than the output voltage of the energy storage device, an over-voltage protection may be carried out and charging may be terminated early - i.e., before the energy storage device is fully charged. (It will be understood that the over-voltage protection is carried out even though the actual output voltage of the energy storage device is less than the over-voltage protection threshold.) The voltage that is provided to the voltage sensing terminal of the protection circuit may be adjusted or varied (e.g., by the controller) so that the charging is terminated by carrying out the over-voltage protection when the remaining capacity or SoC of the energy storage device reaches a threshold value that is dynamically set based on the amount of energy previously consumed and / or the degradation of the energy storage device.

[0033] The aerosol generating device may further comprise a non-inverting amplifier circuit that may be electrically connected between the energy storage device and the voltage sensing terminal of the protection circuit. The non-inverting amplifier circuit amplifies the output voltage of the energy storage device and provides it to the voltage sensing terminal of the protection circuit. As a result, the overvoltage protection may be carried out or performed by the protection circuit at an earlier stage. The noninverting amplifier circuit may comprise a first resistor and a second resistor. The first resistor may be a variable resistor and the second resistor may be a fixed resistor. Alternatively, the first and second resistors may be variable resistors, optionally implemented as a single-chip dual potentiometer. An amplifying ratio of the non-inverting amplifier circuit is defined by the resistance values of the first and second resistors. In general, a variable resistor may be physically larger than a resistor having a fixed resistance value, so using a variable resistor for only the first resistor may allow the amplifying ratio to be adjusted without using too much of the surface area of the printed circuit board. However, if both the first and second resistors are variable resistors, an adjustable range of the amplifying ratio may be increased. In terms of practical implementation, a single-chip dual potentiometer with two variable resistors may therefore be useful because it occupies a smaller surface area of the printed circuit board than two separate variable resistors.

[0034] The controller and the charging circuit may be respectively adapted to use one or more criteria to terminate charging of the energy storage device. Most commercially-available charging ICs are not designed to terminate charging of the energy storage device before it is fully charged. Stability of control should therefore preferably be secured in multiple ways. It may be preferred in view of safety and accuracy of control that both the controller and the charging circuit have at least one criterion for terminating charging of the energy storage device. The one or more criteria may be set so that the charging circuit is adapted to terminate charging of the energy storage device before charging of the

[0035] P51781WO-6677 energy storage device is terminated by the controller (or by the protection circuit). It may be quicker if the charging circuit terminates the charging directly without the need to receive a disable signal from the controller. By prioritising charging termination by the charging circuit, accuracy of the control may be improved.

[0036] A heater of the aerosol generating device may be adapted to heat aerosol generating material provided as part of an aerosol generating article. The aerosol generating article may be adapted to be received in a heating chamber of the aerosol generating device. The heater may be positioned in or adjacent to the heating chamber, and may extend substantially around the heating chamber so that it may heat the aerosol generating material when the aerosol generating article is received in the heating chamber.

[0037] As briefly mentioned above, the aerosol generating material may form part of an aerosol generating article (or “consumable”) and may be surrounded by a paper wrapper.

[0038] The aerosol generating article may be formed substantially in the shape of a stick, and may broadly resemble a cigarette, having a tubular region with an aerosol generating material or substrate arranged in a suitable manner. The aerosol generating article may also be formed as a flat-format article. The aerosol generating article may include a filter segment, for example comprising cellulose acetate fibres, at a proximal end of the aerosol generating article. The filter segment may constitute a mouthpiece filter and may be in coaxial alignment with the aerosol generating material. One or more vapour collection regions, cooling regions, and other structures may also be included in some designs. For example, the aerosol generating article may include at least one tubular segment upstream of the filter segment. The tubular segment may act as a vapour cooling region. The vapour cooling region may advantageously allow the heated vapour generated by heating the aerosol generating material to cool and condense to form an aerosol with suitable characteristics for inhalation by a user, for example through the filter segment.

[0039] The aerosol generating material may comprise any type of solid or semi-solid material. Example types of aerosol generating solids include powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut filler, porous material, foam material or sheets. The aerosol generating material may comprise plant derived material and in particular, may comprise tobacco. It may advantageously comprise reconstituted tobacco, for example including tobacco and any one or more of cellulose fibres, tobacco stalk fibres and inorganic fillers.

[0040] The aerosol generating material may comprise an aerosol-former. Examples of aerosol-formers include polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. Typically, the aerosol generating material may comprise an aerosol-former content of between approximately 5% and approximately 50% on a dry weight basis. In some embodiments, the aerosol generating material may comprise an aerosol-former content of between approximately 10% and approximately 20% on a dry weight basis, and possibly approximately 15% on a dry weight basis.

[0041] P51781WO-6677 The aerosol generating device may be configured to heat the aerosol generating material or substrate, without burning the aerosol generating material, to volatise at least one component of the aerosol generating material and thereby generate a heated vapour which cools and condenses to form an aerosol for inhalation by a user of the aerosol generating device. The volatile compounds released from the aerosol generating material may include nicotine or flavour compounds such as tobacco flavouring.

[0042] In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour may be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

[0043] The aerosol generating device is typically a hand-held, portable, device.

[0044] According to a second aspect of the present disclosure, there is provided a method of controlling an aerosol generating device adapted to generate an aerosol during an operating session in which aerosol generating material is heated, the aerosol generating device comprising an energy storage device; the method comprising terminating charging of the energy storage device when the remaining capacity or state of charge of the energy storage device reaches a threshold value that is less than the capacity or state of charge of the energy storage device when fully charged; and wherein the threshold value is dynamically set based on the amount of energy of the energy storage device consumed in a previous operating session and / or the degradation of the energy storage device.

[0045] The aerosol generating device may further comprise a charging circuit adapted to charge the energy storage device, and a controller. The method may comprise the controller outputting a disable signal to the charging circuit when the remaining capacity or state of charge of the energy storage device reaches the threshold value.

[0046] The method may further comprise summing a buffer voltage and an output voltage of the energy storage device, and outputting the sum of the buffer voltage and the output voltage of the energy storage device to an energy storage device voltage sensing terminal of the charging circuit. The method may further comprise adjusting the buffer voltage based on the threshold value.

[0047] The method may further comprise outputting a voltage to an energy storage device voltage sensing terminal of the charging circuit. The output voltage may be adjusted based on one or both of: (a) the threshold value, and (b) the remaining capacity or state of charge of the energy storage device.

[0048] P51781WO-6677 The aerosol generating device may further comprise a variable resistor electrically connected to a termination current threshold terminal of the charging circuit. The method may further comprise adjusting the resistance value of the variable resistor based on the threshold value.

[0049] The aerosol generating device may further comprise a variable resistor electrically connected between an output charging terminal of the charging circuit and the energy storage device. The method may further comprise adjusting the resistance value of the variable resistor based on the threshold value. The resistance value of the variable resistor may be adjusted based on an internal resistance of the energy storage device.

[0050] The aerosol generating device may further comprise a protection circuit adapted to terminate charging of the energy storage device when a voltage inputted to a voltage sensing terminal is greater than or equal to an over-voltage protection threshold. The method may further comprise providing a voltage that is greater than the output voltage of the energy storage device to the voltage sensing terminal.

[0051] Other features of the aerosol generating and the method may be as described herein.

[0052] Brief Description of the Drawings

[0053] Figure 1 is a diagrammatic cross-sectional view of an aerosol generating system comprising an aerosol generating device and an aerosol generating article ready to be positioned in a heating chamber of the aerosol generating device;

[0054] Figure 2 is a first example of a control circuit of the aerosol generating device;

[0055] Figure 3 is a graph of an example of a charging sequence;

[0056] Figure 4 is a second example of a control circuit of the aerosol generating device;

[0057] Figure 5 is a third example of a control circuit of the aerosol generating device;

[0058] Figure 6 is a fourth example of a control circuit of the aerosol generating device;

[0059] Figure 7 is a fifth example of a control circuit of the aerosol generating device;

[0060] Figure 8 is a sixth example of a control circuit of the aerosol generating device;

[0061] Figure 9 is a seventh example of a control circuit of the aerosol generating device;

[0062] Figure 10 is an eighth example of a control circuit of the aerosol generating device; and Figure 11 is a ninth example of a control circuit of the aerosol generating device.

[0063] Detailed Description of Embodiments

[0064] Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

[0065] Referring initially to Figure 1, there is shown diagrammatically an example of an aerosol generating system 1. The aerosol generating system 1 comprises an aerosol generating device 10 and an aerosol

[0066] P51781WO-6677 generating article 100 for use with the device 10. The aerosol generating device 10 comprises a main body 12 housing various components of the aerosol generating device 10. The main body 12 may have any shape that is sized to fit the components described in the various embodiments set out herein and to be comfortably held by a user unaided, in a single hand.

[0067] A first end 14 of the aerosol generating device 10, shown towards the bottom of Figure 1, is described for convenience as a distal, bottom, base or lower end of the aerosol generating device 10. A second end 16 of the aerosol generating device 10, shown towards the top of Figure 1, is described as a proximal, top or upper end of the aerosol generating device 10. During use, the user typically orients the aerosol generating device 10 with the first end 14 downward and / or in a distal position with respect to the user’s mouth and the second end 16 upward and / or in a proximate position with respect to the user’s mouth.

[0068] The aerosol generating device 10 comprises a heating chamber 18 positioned in the main body 12. The heating chamber 18 defines an interior volume in the form of a cavity 20 having a substantially cylindrical cross-section for receiving an aerosol generating article 100. The heating chamber 18 has a longitudinal axis defining a longitudinal direction and is formed of a heat-resistant plastics material, such as polyether ether ketone (PEEK). The aerosol generating device 10 further comprises an energy storage device 22, for example one or more batteries which are rechargeable, and a control circuit 24. The control circuit 24 may comprise one or more integrated circuits (ICs) and other electronic components. For example, an integrated circuit may comprise at least a microcontroller unit (MCU) 38 and a charging circuit 40. The control circuit 24 may comprise a printed circuit board assembly (PCBA) with a rigid printed circuit board (PCB) on which the one or more electronic components or ICs are mounted.

[0069] The heating chamber 18 is open towards the second end 16 of the aerosol generating device 10. In other words, the heating chamber 18 has an open first end 26 towards the second end 16 of the aerosol generating device 10. The heating chamber 18 is typically held spaced apart from the inner surface of the main body 12 to minimise heat transfer to the main body 12.

[0070] The aerosol generating device 10 may optionally include a sliding cover 28 movable transversely between a closed position (shown in Figure 1) in which it covers the open first end 26 of the heating chamber 18 to prevent access to the heating chamber 18 and an open position (not shown) in which it exposes the open first end 26 of the heating chamber 18 to provide access to the heating chamber 18. The sliding cover 28 may be biased to the closed position in some embodiments.

[0071] The heating chamber 18, and specifically the cavity 20, is arranged to receive a correspondingly shaped generally cylindrical or rod-shaped aerosol generating article 100. Typically, the aerosol generating article 100 comprises a pre-packaged aerosol generating material or substrate 102. The aerosol generating article 100 is a disposable and replaceable article (also known as a “consumable”) which may, for example, contain tobacco as the aerosol generating material 102. The aerosol generating article 100 has

[0072] P51781WO-6677 a proximal end 104 (or mouth end) and a distal end 106. The aerosol generating article 100 further comprises a mouthpiece segment 108 positioned downstream of the aerosol generating material 102. The aerosol generating material 102 and the mouthpiece segment 108 are arranged in coaxial alignment inside a wrapper 110 (e.g., a paper wrapper) to hold the components in position to form the rod-shaped aerosol generating article 100.

[0073] The mouthpiece segment 108 may comprise one or more of the following components (not shown in detail) arranged sequentially and in co-axial alignment in a downstream direction, in other words from the distal end 106 towards the proximal (mouth) end 104 of the aerosol generating article 100: a cooling segment, a centre hole segment and a filter segment. The cooling segment typically comprises a hollow paper tube having a thickness which is greater than the thickness of the wrapper 110. The centre hole segment may comprise a cured mixture containing cellulose acetate fibres and a plasticizer, and functions to increase the strength of the mouthpiece segment 108. The filter segment typically comprises cellulose acetate fibres and acts as a mouthpiece filter. As heated vapour flows from the aerosol generating material 102 towards the proximal (mouth) end 104 of the aerosol generating article 100, the vapour cools and condenses as it passes through the cooling segment and the centre hole segment to form an aerosol with suitable characteristics for inhalation by a user through the filter segment.

[0074] The heating chamber 18 has a side wall (or chamber wall) 30 extending between a base 32, located at a second end 34 of the heating chamber 18, and the open first end 26. The side wall 30 and the base 32 are connected to each other and may be integrally formed as a single piece. In the illustrated embodiment, the side wall 30 is tubular and, more specifically, cylindrical. The side wall 30 may be formed so that the cross-section of the heating chamber 18 is a perfect circle or an ellipse. In other embodiments, the side wall 30 may have other suitable shapes, such as a tube with an elliptical or polygonal cross section. In yet further embodiments, the side wall 30 may be tapered.

[0075] In the illustrated embodiment, the base 32 of the heating chamber 18 is closed, e.g., sealed or air-tight. That is, the heating chamber 18 is cup-shaped. This may ensure that air drawn from the open first end 26 is prevented by the base 32 from flowing out of the second end 34 and is instead guided through the aerosol generating material 102. It may also ensure that a user inserts the aerosol generating article 100 into the heating chamber 18 an intended distance and no further.

[0076] The device 10 includes a heater 36, which is configured to heat the aerosol generating material 102 when the aerosol generating article 100 is received in the heating chamber 18.

[0077] Referring to Figure 2, a first example of the control circuit 24A includes a microcontroller unit (MCU) 38, a charging circuit 40, a low-dropout regulator (LDO) 42, a digital potentiometer 44, a fuel gauge circuit 46, and a protection circuit 48.

[0078] P51781WO-6677 The charging circuit 40 is implemented as an integrated circuit (IC) and includes:

[0079] - an input terminal (labelled “VBUS”) electrically connected to an external power source (not shown) for charging the energy storage device 22, where the external power source provides a charging voltage (labelled “VBUS”),

[0080] - an output charging terminal (labelled “BAT”) electrically connected to the positive terminal of the energy storage device 22 for charging,

[0081] - a system terminal (labelled “SYS”) electrically connected to an input terminal of the LDO 42, where the system terminal provides a system voltage (labelled “VSYS”),

[0082] - a switching node terminal (labelled “SW”) electrically connected to the system terminal by means of an inductor,

[0083] - a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the MCU 38,

[0084] - a termination current threshold terminal (labelled “ITERM”), and

[0085] - an enable terminal (labelled “CE”) electrically connected to a first input / output terminal (labelled “I / O”) of the MCU 38 and which allows the MCU 38 to enable charging of the energy storage device 22 from the external power source (not shown).

[0086] In this embodiment, the enable terminal of the charging circuit 40 works according to negative logic. This means that the charging circuit 40 is enabled when the enable signal (labelled “nENABLE_CHARGE”) that is outputted by the MCU 38 has a low level. When the enable signal that is outputted by the MCU 38 has a high level, the charging circuit 40 is disabled. If an electrical potential of an electrically conductive path to deliver the enable signal from the MCU 38 to the charging circuit 40 is pulled-up to a high electrical potential (e.g., a regulated voltage VDD described in more detail below), an output of the enable signal having a high level for disabling charging by the charging circuit 40 is not always necessary. The enable terminal may also work with positive logic.

[0087] The charging circuit 40 may be used to charge the energy storage device 22 from the external power source (e.g., a universal serial bus (USB) charger or portable charging device, not shown) through the output charging terminal that is electrically connected to the positive terminal of the energy storage device 22. The output voltage at the system terminal of the charging circuit 40 may be provided by the external power source (not shown) and / or the energy storage device 22 that are respectively electrically connected to the input terminal and the output charging terminal of the charging circuit 40. In other words, the charging circuit 40 may allow the external power source (not shown) to charge the energy storage device 22 and provide an output voltage at the system terminal at the same time. When the external power source (not shown) is not connected to the input terminal of the charging circuit 40, the output voltage at the system terminal of the charging circuit 40 is provided by the energy storage device 22.

[0088] P51781WO-6677 The charging circuit 40 carries out a charging sequence with a constant current (or “CC”) mode followed by a constant voltage (or “CV”) mode. An example of a suitable charging sequence is shown in Figure 3. Such a charging sequence is known to be particularly suitable for rapid and safe charging of an energy storage device 22 such as a Li-ion battery, for example. During the CC mode, the energy storage device 22 is charged from the external power source (not shown) for a first period of time using a constant current, and the voltage of the energy storage device 22 increases. When the voltage reaches a predetermined value, the charging sequence switches to the CV mode to avoid the energy storage device 22 falling into an over-charged state. During the CV mode, the energy storage device 22 is charged for a second period of time at a constant voltage until the energy storage device 22 is fully charged. The constant voltage will usually correspond to the desired fully-charged voltage of the energy storage device 22 - i.e., the voltage labelled “VBAT” shown in Figure 3. Compared to the CV mode, the CC mode has a faster charging speed because the amount of charge supplied to the energy storage device 22 per unit of time is greater during the CC mode. During the CV mode, the current will decrease as shown in Figure 3 and charging is completed when the current reaches or falls below a predetermined value, typically referred to as the termination threshold current or cut-off current (labelled “ITERM”). The charging current decreases because the voltage difference between the constant voltage applied by the charging circuit 40 and the output voltage of the energy storage device gradually decreases as the charging sequence progresses. The termination threshold current for the charging circuit 40 may be set depending on the resistance value electrically connected to the termination current threshold terminal of the charging circuit 40. The fully-charged voltage of the energy storage device 22 may be fixed and may not take account of the operating condition of the energy storage device (e.g., degradation, temperature etc.)

[0089] It may also be seen from Figure 3 that during a normal charging sequence which is completed when the current reaches the termination threshold current, the SoC increases from 0% (assuming that the energy storage device 22 is fully discharged) to 100%.

[0090] As explained in more detail below, the charging sequence carried out by the charging circuit 40 may be terminated early by the MCU 38 and / or by the charging circuit 40 - i.e., before the current reaches the initial termination threshold current for fully charging the energy storage device 22.

[0091] The LDO regulator 42 includes:

[0092] - an input terminal (labelled “IN”) electrically connected to the system terminal of the charging circuit 40 and that receives the system voltage,

[0093] - an output terminal (labelled “OUT”) that provides a regulated voltage supply (labelled “VDD”),

[0094] - a ground terminal (labelled “GND”) electrically connected to ground, and

[0095] - an enable terminal (labelled “EN”) electrically connected to the system terminal of the charging circuit 40.

[0096] P51781WO-6677 In this embodiment, the enable terminal of the LDO regulator 42 works according to positive logic and the input and enable terminals of the LDO regulator 42 are electrically connected to the system terminal of the charging circuit 40 in parallel. This means that the LDO regulator 42 continuously outputs a regulated voltage from the output terminal unless the system voltage is unavailable.

[0097] The MCU 38 includes an input voltage terminal (labelled “VDD”) electrically connected to the output terminal of the LDO regulator 42 and receives a regulated voltage supply. As noted above, the MCU 38 includes a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the charging circuit 40, the digital potentiometer 44, and the fuel gauge circuit 46. The MCU 38 also includes:

[0098] - a first input / output terminal (labelled “I / O”) that is electrically connected to the enable terminal of the charging circuit 40 and which outputs the enable signal (labelled “nENABLE_CELARGE”),

[0099] - a second input / output terminal (labelled “I / O”) that is electrically connected to a voltage divider circuit that detects a charging voltage from the external power source (not shown), i.e., where an input signal (labelled “DETECT_VBUS”) has a high level when VBUS is present and a low level otherwise,

[0100] - a third input / output terminal (labelled “I / O”) that receives an output voltage of the energy storage device (labelled “VBAT”) from a voltage divider circuit, and

[0101] - a fourth input / output terminal that is electrically connected to a first semiconductor switch QI for switching it on and off. The first semiconductor switch QI is switched on and off by a control signal (labelled “nON_HEATER”) to control the supply of power from the energy storage device 22 to the heater 36.

[0102] If the first semiconductor switch QI is a p-channel MOSFET, for example, it may be switched on by the MCU 38 if the control signal has a low level and switched off if the control signal has a high level. Alternatively, by arranging an inverting circuit between the first semiconductor switch QI and the fourth input / output terminal, the first semiconductor switch QI may be switched on by the MCU 38 if the control signal has a high level and switched off if the control signal has a low level.

[0103] The digital potentiometer 44 is used to set the termination threshold current for the charging circuit 40 - i.e., the current (labelled “ITERM” in Figure 3) at which the normal charging sequence of the energy storage device 22 is completed. The digital potentiometer 44 includes:

[0104] - a positive power supply terminal (labelled “VDD”) electrically connected to the output terminal of the LDO regulator 42 and receives a regulated voltage supply,

[0105] - a negative power supply terminal (labelled “VSS”) electrically connected to ground,

[0106] - a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the MCU 38,

[0107] P51781WO-6677 - first and second end terminals (labelled “A” and “B”) where the second end terminal is electrically connected to ground, and

[0108] - a wiper terminal (labelled “W”) electrically connected to the termination current threshold terminal of the charging circuit 40.

[0109] The resistance value that is connected to the termination current threshold terminal of the charging circuit 40 is therefore varied by the digital potentiometer 44 under the control of the MCU 38 to set the termination threshold current. The initial value of the termination threshold current will be set so that the energy storage device 22 is fully charged (i.e., is at its maximum charge or where SoC is 100%) when the current reaches or falls below the termination threshold current. If the resistance value is varied so that the termination threshold current is greater than the initial value, the charging sequence may be completed before the energy storage device 22 is fully charged.

[0110] The fuel gauge circuit 46 is implemented as an IC and may accurately measure the remaining capacity and SoC of the energy storage device 22. In particular, it may measure charge and discharge activity by sensing the voltage across a charge current sensing resistor Rj electrically connected in series with the energy storage device 22. By integrating charge passing through the energy storage device 22, the remaining capacity and / or the SoC may be adjusted during charging and discharging. The fuel gauge circuit 46 includes:

[0111] - an energy storage device terminal (labelled “BAT”) electrically connected to the positive terminal of the energy storage device 22,

[0112] - an energy storage device voltage sensing terminal (labelled “BAT_SNS”) electrically connected to the positive terminal of the energy storage device 22,

[0113] - a temperature sensing terminal (labelled “TS”) electrically connected to a temperature sensor 50 (e.g., a thermistor) that provides a voltage signal indicative of a temperature of the energy storage device 22,

[0114] - a ground terminal (labelled “VSS”) electrically connected to ground through the charge current sensing resistor Rj,

[0115] - charge current sensing resistor positive and negative terminals (labelled “SRP” and “SRN”, respectively) electrically connected to the charge current sensing resistor Rs, and

[0116] - a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the MCU 38.

[0117] The charge current sensing resistor Rs is electrically connected to the negative terminal of the energy storage device 22 and to ground through second and third semiconductor switches Q2, Q3 as shown. Alternatively, the charge current resistor Rj may be connected to the positive terminal of the energy storage device 22.

[0118] P51781WO-6677 The energy storage device terminal of the fuel gauge circuit 46 may receive a power supply for operating the circuit. The energy storage device voltage sensing terminal of the fuel gauge circuit 46 may measure the output voltage of the energy storage device 22. In an alternative fuel gauge circuit, the energy storage device terminal and the energy storage device voltage sensing terminal may be combined to a single terminal.

[0119] The protection circuit 48 includes:

[0120] - a voltage sensing terminal (labelled “VDD”) electrically connected to the positive terminal of the energy storage device 22,

[0121] - a charge control output terminal (labelled “CO”) electrically connected to the second semiconductor switching device Q2 for switching it on and off, and

[0122] - a discharge control output terminal (labelled “DO”) electrically connected to the third semiconductor switching device Q3 for switching it on and off.

[0123] The second and third semiconductor switches Q2, Q3 are electrically connected in series between ground and the charge current sensing resistor Rj. When the second semiconductor switch Q2 is switched on, current may flow from the negative terminal of the energy storage device 22 to ground through the charge current sensing resistor Rs, the body diode of the third semiconductor switch Q3, and the second semiconductor switch Q2. When the third semiconductor switch Q3 is switched on, current may flow from ground to the negative terminal of the energy storage device 22 through the body diode of the second semiconductor switch Q2, the third semiconductor switch Q3, and the charge current sensing resistor Rj. Charging and discharging may therefore be stopped by switching the respective semiconductor switch. For example, to terminate charging, the protection circuit 48 may switch the second semiconductor switch Q2 off, e.g., to prevent over-charging of the energy storage device 22. In the control circuit 24A, the protection circuit 48 is adapted to carry out normal over-voltage protection and may be omitted if necessary. This is also the case for the control circuits 24B, 24C, and 24D described below.

[0124] The remaining capacity (in mAh) and SoC of the energy storage device 22 is provided to the MCU 38 from the fuel gauge circuit 46, including during charging. The MCU 38 compares the measured values of the remaining capacity and the SoC against respective threshold values. The threshold values are less than the capacity or SoC of the energy storage device 22 when fully charged. For example, Figure 3 shows a threshold value for the SoC of the energy storage device 22 (labelled “SOCTERM”) that is less than the SoC of the energy storage device 22 when fully charged. If the SoC of the energy storage device 22 that is measured by the fuel gauge circuit 46 reaches or falls below the respective threshold value, the MCU 38 will terminate charging of the energy storage device 22 by sending a disable signal to the enable terminal of the charging circuit 40 - i.e., where the signal nENABLE_CHARGE has a high level. Disabling the charging circuit 40 will immediately terminate charging. In this way, charging may

[0125] P51781WO-6677 be terminated before the current reaches the termination threshold current that is set by the digital potentiometer 44 and the energy storage device 22 is not fully charged (e.g., where SoC is 100%).

[0126] The respective threshold values are dynamically set based on the amount of energy of the energy storage device 22 consumed in a previous operating session and / or the degradation (e.g., SoH) of the energy storage device 22.

[0127] In this particular embodiment, the MCU 38 may calculate the amount of energy consumed in a previous operating session (e.g., a previous vaping session) by comparing the remaining capacity before and after the previous operating session. It may be expected that the amount of energy required for the next operating session will be the same as the amount of energy consumed in a previous operating session because this will typically depend on how the user normally uses the aerosol generating device - e.g., the typical use profile. The threshold value may therefore be set so as to equal to a product of the amount of energy consumed in a previous operating session and a consistent number of operating sessions. This means that during charging, the energy storage device 22 should be charged until the remaining capacity reaches the threshold value rather than until the energy storage device 22 is fully charged. The MCU 38 may convert the threshold value for remaining capacity into the threshold value for the SoC of the energy storage device 22 (i.e., “SOCTERM”). The threshold value for the SoC may also be set based on a difference of the SoC before and after the previous operating session. A buffer to guarantee an amount of energy that may be consumed by other components or by self-discharging of the energy storage device 22 may be added to the calculated threshold value. Instead of directly using the amount of energy consumed in a previous operating session, a moving average of the energy consumed in two or more previous operating sessions may be used. As described above, the threshold value may be defined using a function or lookup table based on the degradation of the energy storage device 22. Such a function or look-up table may be used by itself or in combination with a calculated threshold value based on the amount of energy consumed in one or more previous operating sessions of the aerosol generating device 10.

[0128] Referring to Figure 4, a second example of the control circuit 24B includes a MCU 38, a charging circuit 40, a LDO 42, a digital potentiometer 44, a fuel gauge circuit 46, and a protection circuit 48. The control circuit 24B differs from the control circuit 24A in that it also includes a charge pump 52 and a voltage output circuit 54.

[0129] The charge pump 52 includes:

[0130] - a positive power supply terminal (labelled “VIN”) electrically connected to the system terminal of the charging circuit 40 and that receives the system voltage (labelled “VSYS”),

[0131] - an output terminal (labelled “VOUT”) that outputs a regulated output voltage (labelled “Vcp”),

[0132] - a ground terminal (labelled “GND”) electrically connected to ground,

[0133] - capacitor terminals (labelled “CP+” and “CP-”) electrically connected to a flying capacitor, and

[0134] P51781WO-6677 an enable terminal (labelled “ENA”) electrically connected to the system terminal of the charging circuit 40.

[0135] In this embodiment, the enable terminal of the charge pump 52 works according to positive logic and the input and enable terminals of the charge pump 52 are electrically connected to the system terminal of the charging circuit 40 in parallel. This means that the charge pump 52 continuously outputs a regulated voltage from the output terminal unless the system voltage is unavailable.

[0136] The voltage output circuit 54 is implemented as an IC and includes a digital to analog converter. The voltage output circuit 54 also includes:

[0137] - a positive power supply terminal (labelled “VDD”) electrically connected to the output terminal of the charge pump 52 and receives the regulated output voltage (labelled “VCP”),

[0138] - a voltage reference terminal (labelled “VREFIO”) electrically connected to the output terminal of the charge pump 52 and receives the regulated output voltage as an external reference voltage,

[0139] - an output terminal (labelled “VOUT”) that provides a buffer voltage (labelled “VBUFFER”), and

[0140] - a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the MCU 38 (labelled “SDA#2” and “SCL#2”). It will be noted that the second communication line that connects the serial data and clock terminals of the voltage output circuit 54 to the corresponding terminals of the MCU 38 is separate from the first communication line that is connected between the serial data and clock terminals of the MCU 38 (labelled “SDA#1” and “SCL#1”) and the serial data and clock terminals of the charging circuit 40 and the fuel gauge circuit 46 as shown.

[0141] The first communication line that transmits the remaining capacity or SoC from the fuel gauge circuit 46 may become busy, particularly during charging of the energy storage device 22. For example, at some times during the charging sequence, the remaining capacity or SoC may change frequently and so the first communication line will become very busy - i.e., more signals will be transmitted to the MCU 38 along the first communication line. By isolating the second communication line from the first communication line, the load on the first communication line is reduced because the signals for adjusting the output voltage of the voltage output circuit 54 are transmitted through a separate communication line. This means that the MCU 38 will receive the latest value of the remaining capacity or SoC of the energy storage device 22 and communicate with the voltage output circuit 54 without undue delay.

[0142] The charging circuit 40 includes an energy storage device voltage sensing terminal (labelled “BAT_SNS”) electrically connected to the output terminal of the voltage output circuit 54 and receives the buffer voltage (labelled “VBUFFER”).

[0143] P51781WO-6677 The MCU 38 adjusts the buffer voltage based on the threshold value. In other words, voltage output circuit 54 provides a dummy voltage signal that is higher than the output voltage of the energy storage device 22 to the energy storage device voltage sensing terminal of the charging circuit 40. As a result, the charging circuit 40 may recognise that the charging sequence has progressed further than would be the case if the output voltage of the energy storage device 22 was inputted to the energy storage device voltage sensing terminal. The charging circuit 40 therefore terminates the charging sequence before the energy storage device 22 is fully charged. The magnitude of the buffer voltage outputted by the voltage output circuit 54 is adjusted or varied by the MCU 38 so that the charging is terminated when the remaining capacity or SoC of the energy storage device 22 reaches a threshold value that is dynamically set based on the amount of energy previously consumed and / or the degradation of the energy storage device 22 as described in more detail above.

[0144] As described above, the CC mode is a fast charging mode and a transition from the CC mode to the CV mode is based on a voltage of the energy storage device 22 that is being charged. The early transition to the C V mode based on a dummy voltage signal that is higher than the output voltage of the energy storage device 22 may be advantageous to limit an amount of charge to be inputted into the energy storage device 22.

[0145] Referring to Figure 5, a third example of the control circuit 24C includes a MCU 38, a charging circuit 40, a LDO 42, a digital potentiometer 44, a fuel gauge circuit 46, a protection circuit 48, a charge pump 52, and a voltage output circuit 54. The control circuit 24C differs from the control circuit 24B in that it also includes an operational amplifier 56 as a non-inverting adder circuit. The operational amplifier 56 includes:

[0146] - a positive power supply terminal electrically connected to the output terminal of the charge pump 52 and receives the regulated output voltage (labelled “Vcp”),

[0147] - a non-inverting input terminal (labelled “+”) that is electrically connected to the positive terminal of the energy storage device 22 and the output terminal of the voltage output circuit 54 so that it receives the output voltage of the energy storage device 22 and the buffer voltage as described above,

[0148] - an inverting input terminal (labelled electrically connected to ground by means of a first resistor, and

[0149] - an output terminal electrically connected to the energy storage device voltage sensing terminal of the charging circuit 40 and the inverting input terminal by means of a second resistor. The inverting terminal is therefore electrically connected to a junction of the series-connected first and second resistors that are electrically connected between the output terminal and ground.

[0150] The operational amplifier 56 therefore outputs the sum of the buffer voltage and the output voltage of the energy storage device 22 to the energy storage device voltage sensing terminal of the charging circuit 40. The MCU 38 adjusts the buffer voltage based on the threshold value. In other words, the operational

[0151] P51781WO-6677 amplifier 56 provides a dummy voltage signal that is higher than the output voltage of the energy storage device 22 to the energy storage device voltage sensing terminal of the charging circuit 40. As a result, the charging circuit 40 may recognise that the charging sequence has progressed further than would be the case if the output voltage of the energy storage device 22 was inputted to the energy storage device voltage sensing terminal. The charging circuit 40 therefore terminates the charging sequence before the energy storage device 22 is fully charged. The magnitude of the buffer voltage outputted by the voltage output circuit 54 is adjusted or varied by the MCU 38 so that the charging is terminated when the remaining capacity or SoC of the energy storage device 22 reaches a threshold value that is dynamically set based on the amount of energy previously consumed and / or the degradation of the energy storage device 22 as described in more detail above.

[0152] As compared with the second example of the control circuit 24B, where the buffer voltage is inputted directly to the energy storage device voltage sensing terminal of the charging circuit 40, the value of the buffer voltage may be small. The dummy voltage signal that is output by the operational amplifier 56 is dynamically shifted with the output voltage of the energy storage device 22 during charging and more stable charging may be realised. However, by adding the operational amplifier 56 the complexity of the control circuit 24C is increased. Because the magnitude of the buffer voltage outputted by the voltage output circuit 54 may be relatively small, inputting the regulated output voltage from the charge pump 52 (labelled “Vcp”) into the positive power supply terminal of the output voltage circuit 54 is not mandatory. In Figure 5, the regulated voltage from the LDO regulator 42 (labelled “VDD”) is inputted into the positive power supply terminal of the output voltage circuit 54 instead of the regulated output voltage from the charge pump 52.

[0153] Referring to Figure 6, a fourth example of the control circuit 24D includes a MCU 38, a charging circuit 40, a LDO 42, a digital potentiometer 44, a fuel gauge circuit 46, a protection circuit 48, and a voltage output circuit 54. The control circuit 24D differs from the control circuit 24C in that it includes a boost converter 58 instead of the charge pump 52.

[0154] The boost converter 58 includes:

[0155] - an input terminal (labelled “VIN”) electrically connected to the system terminal of the charging circuit 40 and that receives the system voltage,

[0156] - an output terminal (labelled “VOUT”) that outputs a regulated output voltage (labelled “VBOOST”),

[0157] - a ground terminal (labelled “GND”) electrically connected to ground,

[0158] - a switching node terminal (labelled “SW”) electrically connected to the input terminal by means of an inductor, and

[0159] - an enable terminal (labelled “EN”) electrically connected to the system terminal of the charging circuit 40.

[0160] P51781WO-6677 In this embodiment, the enable terminal of the boost converter 58 works according to positive logic and the input and enable terminals of the boost converter 58 are electrically connected to the system terminal of the charging circuit 40 in parallel. This means that the boost converter 58 continuously outputs a regulated voltage from the output terminal unless the system voltage is unavailable.

[0161] The positive power supply terminal of the operational amplifier 56 is electrically connected to the output terminal of the boost converter 58. The maximum output voltage of the operational amplifier 56 corresponds to the difference between the electrical potential at the positive and negative power supply terminals. If the negative power supply terminal is electrically connected to ground, the maximum output voltage is equal to the voltage that is supplied to the positive power supply terminal - in this case, the boosted output voltage from the boost converter 58. The dummy voltage signal that is output by the operational amplifier 56 must be higher than the output voltage of the energy storage device 22. This means that the system voltage (i.e., “VSYS”) and the regulated output voltage from the LDO regulator 42 (i.e., “VDD”) are not suitable for the operational amplifier 56. In the control circuit 24C the higher supply voltage is provided by the charge pump 52. But in the control circuit 24D the higher supply voltage for the operational amplifier 56 is provided by the boost converter (or switched regulator) 58. The boost converter 58 and its inductor will occupy a larger surface area of the printed circuit board on which the various circuit components are mounted. But the boost converter 58 may handle a larger current. The boosted output voltage is also conveniently supplied to the heater 36 as shown in Figure 6. In particular, the same boost converter 58 may be used to supply the boosted voltage to the heater 36 for improved heating efficiency. To further improve the efficiency, the output voltage of the energy storage device 22 (labelled “VBAT”) may be inputted into the input and enable terminals (labelled “VIN” and “EN”) of the boost converter 58 instead of the system voltage (labelled “VSYS”).

[0162] Referring to Figure 7, a fifth example of the control circuit 24E includes a MCU 38, a charging circuit 40, a LDO 42, a first digital potentiometer 44, a fuel gauge circuit 46, a protection circuit 48, a second digital potentiometer 60, and a third digital potentiometer 62.

[0163] The second digital potentiometer 60 includes:

[0164] - a positive power supply terminal (labelled “VDD”) electrically connected to the output voltage terminal of the LDO regulator 42 and receives a regulated voltage supply (labelled “VDD”),

[0165] - a negative power supply terminal (labelled “VSS”) electrically connected to ground,

[0166] - a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the MCU 38,

[0167] - first and second end terminals (labelled “A” and “B”) where the second end terminal is electrically connected to the positive terminal of the energy storage device 22 and receives an output voltage of the energy storage device (labelled “VBAT”), and

[0168] P51781WO-6677 a wiper terminal (labelled “W”) electrically connected to the output charging terminal (labelled “BAT”) of the charging circuit 40.

[0169] The second digital potentiometer 60 is electrically connected between the output charging terminal of the charging circuit 40 and the positive terminal of the energy storage device 22. The MCU 38 is adapted to adjust the resistance value of the second digital potentiometer 60 based on the threshold value and / or an internal resistance of the energy storage device 22. Due to the internal resistance of the energy storage device 22, the energy storage device 22 and the second digital potentiometer 60 form a voltage divider circuit. A charging voltage outputted from the output charging terminal of the charging circuit 40 is divided by this voltage divider circuit so that a lower voltage is applied to the energy storage device 22. A lower charging voltage is applied to the energy storage device 22 and charging may be terminated early - i.e., before the energy storage device 22 is fully charged. In addition, because the MCU 38 may adjust the resistance value of the second digital potentiometer 60, the termination time of the charging sequence may be more flexibly adjusted.

[0170] The third digital potentiometer 62 is implemented as a dual digital potentiometer and includes:

[0171] - a positive power supply terminal (labelled “VDD”) electrically connected to the output voltage terminal of the LDO regulator 42 and receives a regulated voltage supply (labelled “VDD”),

[0172] - a ground terminal (labelled “GND”) electrically connected to ground,

[0173] - a serial data terminal (labelled “SDA”) and a serial clock terminal (labelled “SCL”) that are electrically connected to corresponding terminals of the MCU 38,

[0174] - first and second end terminals (labelled “Al” and “Bl”),

[0175] - a first wiper terminal (labelled “Wl”),

[0176] - third and fourth end terminals (labelled “A2” and “B2”), and

[0177] - a second wiper terminal (labelled “W2”).

[0178] The second end terminal (i.e., the end terminal labelled “Bl”) is electrically connected to ground.

[0179] An operational amplifier 64 includes:

[0180] - a non-inverting input terminal electrically connected to the positive terminal of the energy storage device 22,

[0181] - an inverting input terminal electrically connected to the first wiper terminal and the fourth end terminal (i.e., the end terminal labelled “B2”) of the third digital potentiometer 62, and

[0182] - an output terminal electrically connected to the second wiper terminal and the voltage sensing terminal (labelled “VDD”) of the protection circuit 50.

[0183] The operational amplifier 64 and the third digital potentiometer 62 form a non- inverting amplifier circuit.

[0184] P51781WO-6677 As explained above, if the voltage that is provided to the voltage sensing terminal of the protection circuit 48 is greater than the output voltage of the energy storage device 22, an over-voltage protection may be carried out and charging may be terminated early - i.e., before the energy storage device 22 is fully charged. The voltage that is provided to the voltage sensing terminal of the protection circuit 48 is adjusted or varied by the MCU 38 so that the charging is terminated by carrying out over-voltage protection when the remaining capacity or SoC of the energy storage device 22 reaches a threshold value that is dynamically set based on the amount of energy previously consumed and / or the degradation of the energy storage device as described in more detail above. The operational amplifier 64 is electrically connected between the energy storage device 22 and the voltage sensing terminal of the protection circuit 48. The operational amplifier 64 amplifies the output voltage of the energy storage device 22 and provides it to the voltage sensing terminal of the protection circuit 48. As a result, the over-voltage protection may be initiated by the protection circuit 48 at an earlier stage. The non-inverting amplifier circuit includes a first resistor Ri and a second resistor R2. In the control circuit 24E shown in Figure 7, the first and second resistors Ri, R2 are variable resistors implemented by the third digital potentiometer 62 (i.e., as a dual digital potentiometer). In the sixth example of a control circuit 24F shown in Figure 8, the first resistor Ri is a fixed resistor and the second resistor is implemented by the third digital potentiometer 62. In the seventh example of a control circuit 24G shown in Figure 9, the first resistor is implemented by the third digital potentiometer 62 and the second resistor R2 is fixed. An amplifying ratio of the non-inverting amplifier circuit is defined by the resistance values of the first and second resistors Ri, R2, i.e., where: is the output voltage of the operational amplifier 64 and F / MTis the output voltage of the energy storage device 22 inputted to the non-inverting terminal of the operational amplifier 64. If both the first and second resistors Ri, R2 are variable resistors, the adjustable range of the amplifying ratio may therefore be increased.

[0185] Referring to Figure 10, an eighth example of the control circuit 24H is similar to the control circuit 24E shown in Figure 7, but the first, second and third digital potentiometers are implemented together as a quad digital potentiometer 66.

[0186] In the fifth, sixth and seventh control circuits 24E, 24F and 24G shown in Figures 7 to 9, the second digital potentiometer 60 is used together with the third digital potentiometer 62. But it will be understood that this is not always required. In practice, just one of the second and third digital potentiometers 60, 62 may be used. For example, referring to Figure 11 , a ninth example of the control circuit 241 is similar to the control circuit 24E shown in Figure 7, but the second digital potentiometer 60 is omitted and the output charging terminal (labelled “BAT”) of the charging circuit 40 is electrically connected directly to

[0187] P51781WO-6677 the positive terminal of the energy storage device 22. This may improve charging and discharging efficiency of the energy storage device 22 because it avoids the need for the charging and discharging current to flow through the second digital potentiometer 60.

[0188] Like the second control circuit 24B shown in Figure 4, separate communication lines may be used in the other control circuits 24C to 251. For example, a dedicated communication line with the MCU 38 may be used for one or more of the fuel gauge circuit 46, the voltage output circuit 54, the second digital potentiometer 60, the third digital potentiometer 62, and the quad digital potentiometer 66.

[0189] Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

[0190] Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0191] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0192] P51781WO-6677

Claims

- 27 -Claims1. An aerosol generating device (10) adapted to generate an aerosol during an operating session in which aerosol generating material is heated, the aerosol generating device (10) comprising: an energy storage device (22); a charging circuit (40) adapted to charge the energy storage device (22); and a controller (38); wherein at least one of the controller (38) and the charging circuit (40) is adapted to terminate charging of the energy storage device (22) when the remaining capacity or state of charge of the energy storage device (22) reaches a threshold value that is less than the capacity or state of charge of the energy storage device (22) when fully charged; and wherein the threshold value is dynamically set based on the amount of energy of the energy storage device (22) consumed in a previous operating session and / or the degradation of the energy storage device (22).

2. An aerosol generating device (10) according to claim 1, wherein the controller (38) is adapted to output a disable signal to the charging circuit when the remaining capacity or state of charge of the energy storage device (22) reaches the threshold value.

3. An aerosol generating device (10) according to claim 1 or claim 2, further comprising: a digital to analog converter (54) adapted to output a buffer voltage; and a non- inverting adder circuit (56) adapted to sum the buffer voltage and an output voltage of the energy storage device (22) and to output the sum of the buffer voltage and the output voltage of the energy storage device (22) to an energy storage device voltage sensing terminal of the charging circuit (40); wherein the controller (38) is adapted to adjust the buffer voltage based on the threshold value.

4. An aerosol generating device (10) according to claim 3, wherein the non-inverting adder circuit comprises an operational amplifier (56) with a positive power supply terminal, and wherein the aerosol generating device (10) further comprises: a boost converter (58) adapted to output a boosted voltage; and a heater (36) adapted to heat the aerosol generating material; wherein the positive power supply terminal of the operational amplifier (56) and the heater (36) are electrically connected to the boost converter (58).

5. An aerosol generating device (10) according to claim 1 or claim 2, further comprising a digital to analog converter (54) adapted to output a voltage to an energy storage device voltage sensing terminal of the charging circuit (40), wherein the controller (38) is adapted to adjust the output voltage of the digital to analog converter based (54) on one or both of: (a) the threshold value, and (b) the remaining capacity or state of charge of the energy storage device (22).P51781WO-66776. An aerosol generating device (10) according to claim 5, wherein the controller (38) is adapted to receive the remaining capacity or state of charge of the energy storage device (22) through a first communication line, and is adapted to adjust the output voltage of the digital to analog converter (54) through a second communication line that is isolated from the first communication line.

7. An aerosol generating device (10) according to claim 1 or claim 2, further comprising a variable resistor (44) electrically connected to a termination current threshold terminal of the charging circuit (40), and wherein the controller (38) is adapted to adjust the resistance value of the variable resistor (44) based on the threshold value.

8. An aerosol generating device (10) according to claim 1 or claim 2, further comprising a variable resistor (60) electrically connected between an output charging terminal of the charging circuit (40) and the energy storage device (22), and wherein the controller (38) is adapted to adjust the resistance value of the variable resistor (60) based on the threshold value.

9. An aerosol generating device (10) according to claim 8, wherein the controller (38) is further adapted to adjust the resistance value of the variable resistor (60) based on an internal resistance of the energy storage device (22).

10. An aerosol generating device (10) according to any preceding claim, further comprising a protection circuit (48) adapted to terminate charging of the energy storage device (22) when a voltage inputted to a voltage sensing terminal is greater than or equal to an over-voltage protection threshold, and wherein a voltage that is greater than the output voltage of the energy storage device (22) is adapted to be provided to the voltage sensing terminal.

11. An aerosol generating device (10) according to claim 10, further comprising a non-inverting amplifier circuit (62, 64) electrically connected between the energy storage device (22) and the voltage sensing terminal of the protection circuit (48).

12. An aerosol generating device (10) according to claim 11, wherein the non-inverting amplifier circuit (62, 64) comprises a first resistor (Ri) and a second resistor (R?), and wherein the first resistor (Ri) is a variable resistor and the second resistor (R2) is a fixed resistor.

13. An aerosol generating device (10) according to claim 11, wherein the non-inverting amplifier circuit (62, 64) comprises a first resistor (Ri) and a second resistor (R2), and wherein the first and second resistors (Ri, R2) are variable resistors, optionally implemented as a single-chip dual potentiometer.P51781WO-667714. An aerosol generating device (10) according to any preceding claim, wherein the controller (38) and the charging circuit (40) are respectively adapted to use one or more criteria to terminate charging of the energy storage device (22).

15. An aerosol generating device (10) according to claim 14, wherein the one or more criteria are set so that the charging circuit (40) is adapted to terminate charging of the energy storage device (22) before charging of the energy storage device (22) is terminated by the controller (38).P51781WO-6677

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