Aerosol generating system and a method of controlling an aerosol generating system

Abstract

An aerosol generating system is described. The system includes a capacitor formed as a flexible tape (10), e.g., as a long, narrow flexible strip of multi-layer material. The capacitor tape (10) includes aerosolisable electrolyte which, when heated, generates an aerosol for inhalation by a user. The capacitor tape (10) includes a separator layer (14) that is sandwiched between a pair of carbon-based electrode layers (12a, 12b). The electrode layers (12a, 12b) and the separator layer (14) contain the electrolyte. The capacitor tape (10) may be part of a removable cassette or cartridge that is received in a compartment of an aerosol generating device in use. The aerosol generating device may include a pair of parallel counter rotating rollers (32a, 32b) that are in physical and electrical contact with the capacitor tape (10).

Description

[0001] AEROSOL GENERATING SYSTEM AND A METHOD OF CONTROLLING AN AEROSOL GENERATING SYSTEM

[0002] Technical Field

[0003] The present disclosure relates generally to an aerosol generating system, and in particular to an aerosol generating system that may include an aerosol generating article adapted to be received in an aerosol generating device for generating an aerosol for inhalation by a user.

[0004] The present disclosure is particularly applicable to a portable (hand-held) aerosol generating device.

[0005] The present disclosure also relates to a method of controlling an aerosol generating system.

[0006] Technical Background

[0007] Devices which heat, rather than burn, 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-burn 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. 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.

[0008] Such devices may use one of a number of different approaches to provide heat to the aerosol generating material. All approaches for heating the aerosol generating material require some sort of power source such as a battery, which adds to the size and weight of the device. Embodiments of the present disclosure seek to provide a power source in the aerosol generating article which may be used to supplement or partially replace the power source in the device and there is no need for a separate heater. This may result in a smaller and lighter device, which is beneficial for the user, while maintaining accurate control of the heating of the aerosol generating material and optimising the characteristics of the generated aerosol. The present disclosure also seeks to provide an aerosol generating article (or consumable) that has no metallic components and is more environmentally friendly.

[0009] Summary of the Disclosure

[0010] According to a first aspect of the present disclosure, there is provided an aerosol generating system comprising a capacitor formed as a flexible tape (e.g., as a long, narrow flexible strip with multiple layers), the capacitor comprising aerosolisable electrolyte which, when heated, generates an aerosol for inhalation by a user. The electrolyte is aerosolisable, i.e., capable of being converted into an aerosol by heating, which aerosol is then inhaled by the user. Heating the capacitor therefore results in the electrolyte that is contained within the capacitor being converted into an aerosol and the aerosolised electrolyte is then inhaled by the user, for example through a mouthpiece.

[0011] The aerosol generating system may comprise an aerosol generating article and an aerosol generating device that is adapted to receive, in use, the aerosol generating article. The capacitor may be part of the aerosol generating article.

[0012] In the following disclosure the terms “capacitor” and “capacitor tape” are used interchangeably, the latter typically being used when describing the interaction between the capacitor tape and electrically conductive rollers that provide an electrical connection between the capacitor tape and an external circuit such as a switching circuit and which may be rotated to move the capacitor tape, or when it is necessary to underline the fact that the capacitor is formed as a long, narrow flexible strip.

[0013] The electrolyte in the capacitor tape is heated by charging and / or discharging the capacitor. For example, the capacitor may be charged or discharged, or may be cycled between discharging and charging to heat the electrolyte. The capacitor may have any suitable construction, but in a preferred embodiment it is a supercapacitor such as an electric double-layer supercapacitor. The capacitor may further comprise a pair of electrodes and a porous separator between the electrodes. The porous separator may be adjacent the first and second electrodes - i.e., so that the separator is sandwiched between the first and second electrodes to prevent a short- circuit therebetween. The first electrode may be a positive electrode and the second electrode may be a negative electrode, or vice versa. The electrodes and the separator are immersed in or contain the electrolyte. The electrodes and the porous separator may be formed as long, narrow flexible strips of material that define different layers of the capacitor tape. The capacitor tape may have a thickness of between about 0.5 mm and about 5.0 mm and a width of between about 5.0 mm and about 30 mm, for example. The capacitor tape may be provided in different lengths where each length corresponds generally to a total number of puffs. For example, the capacitor may have a length of between about 50 cm and about 500 cm.

[0014] Like a conventional capacitor, in an electric double-layer supercapacitor electrical charge is stored in the electrical field between the electrodes and the capacitance is a function of the surface area of the electrodes, the distance between them, and the dielectric constant of the separator material. The capacitor has a higher power density than a conventional power source such as a battery. When the capacitor is charged by an external circuit connected to the pair of electrodes, cations in the electrolyte migrate toward the negative electrode and the anions migrate to the positive electrode, while the electrons travel through the external circuit from the negative to the positive electrode. Two layers of charge with opposite polarity (an electric double-layer) are therefore formed at the interfaces with the electrodes. When charging finishes, positive electric charges on the positive electrode and anions in the electrolyte attract each other while negative electric charges on the negative electrode and cations in the electrolyte attract each other in order to stabilize the double layers on the electrodes. A stable voltage is generated. When the capacitor is discharged, the reverse processes happen. Each electrode may comprise at least one carbon-based electrode layer, for example, a layer of porous charcoal material or activated carbon which has a high specific surface area per volume and compatibility with the proposed electrolyte. A layer of separator material may be sandwiched between the two carbon-based electrode layers.

[0015] As will be understood the electrolyte fulfils two functions. Firstly it permits the cation and anion migration that occurs when the capacitor is charged or discharged, and secondly, when heated, it forms an aerosol that is safe to be inhaled by the user and has good characteristics. The electrolyte should therefore be selected accordingly. The electrolyte is preferably a food-grade electrolyte and may comprise one or more of sodium chloride, sodium citrate, sodium bicarbonate, potassium chloride, calcium lactate, calcium carbonate, tricalcium phosphate, magnesium citrate, magnesium carbonate, citric acid, tartaric acid, benzoic acid, glycerol and any suitable equivalents, for example. The electrolyte may optionally include a gelling agent such as polyvinyl alcohol, gellan gum or xanthan gum, for example. In one example, the electrolyte may comprise sodium chloride and glycerol, and optionally polyvinyl alcohol as a gelling agent. Such an electrolyte has been found to permit cation and anion migration and is also safe for inhalation by the user.

[0016] The separator must provide dielectric separation between the pair of oppositely charged electrodes. The separator also stores electrolyte in its pores and permits the passage of cations and anions during the charging and discharging processes. The separator may comprise any suitable material. The porous separator may comprise a flavour source medium. The separator may comprise a plant derived material and in particular may comprise a tobacco material, for example, a porous tobacco sheet, or it may comprise any suitable cellulose- or polypropylene-based material. When heated, the separator material may release one or more volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco or other flavouring.

[0017] The aerosol generating system may further comprise a pair of electrically conductive rollers. The rollers may be part of the aerosol generating device, for example. The rollers may be made of any suitable electrically conductive material, e.g., aluminium. The rollers are mounted in parallel for counter rotation and define a gap therebetween (sometimes called a “nip gap”) through which the capacitor tape is received. In other words, one of the rollers will rotate in a first direction (e.g., a clockwise direction) and the other one of the rollers will rotate in a second, opposite, direction (e.g., an anticlockwise direction). The gap is such that the part of the capacitor tape that is received through the gap is in electrical and physical contact with the rollers.

[0018] A heating space of the aerosol generating system is provided between the rollers. The part of the capacitor tape that is received through the gap between the rollers, and which is therefore also located in the heating space, is heated when the capacitor is charged and / or discharged as described in more detail below. This localised heating of the part of the capacitor tape that is located in the heating space generates aerosol which may be inhaled by the user. The electrolyte in the part of the capacitor tape that is being heated may be partially or fully consumed to generate aerosol that is inhaled by the user in one or more puffs. It will be understood that the parts of the capacitor tape that are located outside of the heating space will not be significantly heated. An aerosol may be generated by heating the part of the capacitor tape that is located in the heating space until the electrolyte in that part of the capacitor tape is substantially consumed. It is then necessary to move the capacitor tape so that another part of the capacitor tape with electrolyte is located in the heating space. The term “upstream” may be used in the present disclosure to describe that part of the capacitor tape on one side of the rollers that has not yet been positioned in the heating space and which still contains electrolyte, and the term “downstream” may be used to describe that part of the capacitor tape on the other side of the rollers that has already been positioned in the heating space and where at least part of its electrolyte has been consumed.

[0019] The rollers are preferably biased towards each other to apply a clamping pressure to the capacitor tape that is received in the gap. As well as making sure that the rollers are in direct physical contact with the capacitor tape, the clamping pressure is preferably applied at a level that will reduce the electrical resistance of the part of the capacitor tape that is in electrical and physical contact with the rollers so that it may be properly charged and / or discharged. This may avoid the need for further additives in the electrolyte to reduce electrical resistance. If the electrical resistance of the capacitor tape is too high, an electric current will not flow and the electrolyte can normally only be aerosolised when a sufficiently high clamping pressure is applied by the rollers. The clamping pressure may be applied to the rollers using one or more compression springs or other suitable biasing elements, for example.

[0020] The rollers may be adapted to be driven to rotate to feed the capacitor tape through the gap. In other words, because the rollers are in physical contact with the capacitor tape, rotating one of the rollers in the first direction and the other roller in the second, opposite, direction will feed the capacitor tape through the gap in a transport direction. (Reversing the direction in which each roller is rotated will feed the capacitor tape in a reverse direction, which may be used for example to wind the capacitor tape back onto an upstream supply spool once all of the electrolyte in the capacitor tape has been consumed.) The rollers may therefore be used to selectively feed the capacitor tape in the transport direction in response to user manipulation of the aerosol generating system. For example, the rollers may be rotated in response to a puff being detected, or after the user has taken one or more puffs. For example, if the part of the capacitor tape that is located in the heating space contains enough electrolyte to generate enough aerosol for n puffs, where n is an integer, the capacitor tape may be moved after n puffs have been taken by the user. (In practice, it may be that each part of the capacitor tape contains enough electrolyte to generate enough aerosol for slightly more than n puffs so that the quality of each puff is maintained, in other words the quality of the last puff is not compromised.) Each puff may be detected by a suitable puff detector. Moving the capacitor tape along the transport direction means that a new part of the capacitor tape is located in the heating space and is in electrical and physical contact with the rollers. After the electrolyte in a particular part of the capacitor tape has been aerosolised (i.e., fully or partly consumed), the capacitor tape is moved in the transport direction so that a new part of the capacitor tape is positioned in the heating space and its electrolyte may be aerosolised in turn. Rotating each roller through a particular angle of rotation will move the capacitor tape a particular distance in the transport direction. For every puff (or every or two or more puffs, if each part of the capacitor tape includes enough electrolyte to generate enough aerosol for more than one puff) a new part of the capacitor tape may be positioned in the heating space. As mentioned above, the capacitor tape may be designed to provide a total number of puffs before all of the electrolyte in the capacitor tape is consumed and the capacitor tape needs to be replaced. The total number of available puffs may depend, for example, on the length of the tape and / or the number of puffs that may be extracted from each part of the tape when it is positioned in the heating space of the aerosol generating system for localised heating. It will be understood that a longer capacitor tape will normally provide more puffs before it needs to be replaced and vice versa.

[0021] The rollers may also be used to selectively feed the capacitor tape in a reverse direction after all (or substantially all) of the electrolyte in the capacitor tape has been consumed.

[0022] The rollers may be driven to rotate by a suitable driver such as one or more actuators (e.g., one or more electric motors). The one or more actuators may be controlled by a controller and may form part of an aerosol generating device. The one or more actuators may receive power from a power source of the aerosol generating device, e.g., a rechargeable battery.

[0023] A switching circuit may be electrically connected between the pair of rollers and adapted to control the discharging of the capacitor, and optionally the charging of the capacitor from a power source. The power source may be a rechargeable battery of the aerosol generating device, for example. The switching circuit may be part of the aerosol generating device and may be electrically connected to each roller by a rotary electrical interface, e.g., a slip ring assembly with carbon brushes. More particularly, each roller may include a ring that is in sliding contact with a stationary brush mounted in a brush assembly. Each brush is electrically connected to a respective terminal of the switching circuit. For example, one of the rollers may be electrically connected to a positive terminal of the switching circuit through a first brush and will therefore also be in electrical contact with the positive electrode of the capacitor tape, and the other roller may be electrically connected to a negative terminal of the switching circuit through a second brush and will therefore also be in electrical contact with the negative electrode of the capacitor tape. Other rotary electrical interfaces may also be used. The rollers define current collectors for the capacitor tape. Preferably the capacitor tape itself does not comprise a current collector which might normally be a metal foil layer, for example, an aluminium foil layer, adjacent the electrode layers. Put another way, the capacitor tape preferably does not contain any metal components. It therefore provides a fully sustainable solution when it is necessary to dispose of the used capacitor tape. The cost of the consumable capacitor tape may also be reduced. Because the capacitor tape is only normally in contact with the rollers - i.e., with metallic components - immediately prior to the electrolyte being aerosolised, current collector corrosion is limited.

[0024] The capacitor tape may be supplied from an upstream supply spool. The upstream supply spool may be part of a replaceable cassette or cartridge that may be inserted into the aerosol generating device, for example. The aerosol generating article may comprise the cassette or cartridge and its associated components including the capacitor tape. However, the aerosol generating article may comprise only the capacitor tape and a supply spool or other means from which the capacitor tape may be supplied. The cassette or cartridge may be received in a corresponding space or compartment in the aerosol generating device in such a way that the capacitor tape is received between the pair of rollers. A housing of the aerosol generating device may comprise a cover which may be opened to allow the cassette or cartridge to be inserted into and removed from the compartment, for example. It may be difficult to remove the capacitor tape if the rollers remain in physical contact with the capacitor tape and the clamping force is still being applied. It may also be difficult to insert a new capacitor tape. The gap between the rollers may therefore be increased temporarily when the cassette or cartridge is being removed or when a new cassette or cartridge is being inserted. More particularly, the rollers may be moved apart, optionally against the bias of the compression springs or other biasing elements that apply the clamping pressure, so that the capacitor tape may be more easily removed from the gap between the rollers or inserted into the gap. The gap may be reduced to bring the rollers back into direct electrical and physical contact with the capacitor tape of the newly inserted cassette or cartridge. The capacitor tape may be fed from the pair of rollers to a downstream waste spool. In other words, the cassette or cartridge may comprise a supply spool and a waste spool where the downstream end of the capacitor tape is connected to the waste spool. When the cassette or cartridge is located in the compartment of the aerosol generating device, the rollers may be located between the supply spool and the waste spool - similar to a tape head that is adapted to read a conventional two-spool cassette with magnetic tape. Alternatively, the used or downstream part of the capacitor tape may be captured inside a housing of the aerosol generating device. This would include being captured within a removable cassette or cartridge that is located inside the housing. It will be clear that the downstream part of the capacitor tape means the part that is on the opposite side of the rollers to the supply spool.

[0025] If the cassette or cartridge includes a waste spool, it may be driven to rotate when the rollers are rotated (or afterwards) to take up the used capacitor tape. The supply spool does not normally need to be driven to rotate - it may be mounted to be freely rotatable so that capacitor tape is supplied from the supply spool towards the heating space in the transport direction when the rollers are rotated. However, the supply spool may be driven to rotate if the rollers are rotated in a reverse direction to take up the used capacitor tape, e.g., after all of the electrolyte has been consumed. Such an arrangement may allow the used capacitor tape to be temporarily captured within the housing (for example, within the removable cassette or cartridge) and then wound back on to the supply spool. This may avoid the need for a separate waste spool. A spool may be rotated by a suitable driver such as a hub that engages with the spool and an actuator (e.g., an electric motor) that rotates the hub. The hub may be located in the space or compartment of the aerosol generating device and the driver may be part of the device. The hub may include one or more teeth or other engagement means that engage with the spool - e.g., an inner part of the spool that receives the hub - when the spool is located in the compartment in use. Each electric motor may be controlled by the controller and may receive power from the power source of the aerosol generating device. Once all of the electrolyte in the capacitor tape has been aerosolised or all of the capacitor tape has been used, the cassette or cartridge (or other type of aerosol generating article) may be removed and a new one inserted into the aerosol generating device by the user.

[0026] The supply spool and the waste spool may be made of a suitable plastics material. The other parts of the removable cassette or cartridge may also be made of a suitable plastics material so that the cassette or cartridge (or aerosol generating article) does not contain any metallic components. This may make it easier for the cassette or cartridge to be recycled or disposed of in a more environmentally friendly way.

[0027] The aerosol generating system (or more particularly, the aerosol generating device) may comprise a housing with an opening. The capacitor tape may be fed from the pair of rollers to the opening such that a downstream part of the capacitor tape extends beyond the opening (i.e., it projects outside the housing). The aerosol generating system may further comprise a cutter adjacent the opening adapted to cut away the downstream part of the capacitor, i.e., the used capacitor tape. The cutter may be activated automatically or manually.

[0028] As described above, an aerosol generating article may be in the form of a cassette or cartridge that includes the following parts:

[0029] - a capacitor tape comprising aerosolisable electrolyte,

[0030] - a supply spool, and

[0031] - an optional waste spool.

[0032] The aerosol generating device may include one or more of the following parts:

[0033] - a pair of rollers with associated drivers or actuators (e.g., one or more electric motors) and rotary electrical interface,

[0034] - an external circuit (e.g., a switching circuit) electrically connected between the rollers,

[0035] - a mouthpiece through which the aerosol may be inhaled by the user,

[0036] - a puff detector, e.g., a flow detector, - a power source, e.g., one or more rechargeable batteries,

[0037] - a controller,

[0038] - a housing,

[0039] - a compartment for receiving a removable cassette or cartridge, or other aerosol generating article that includes the capacitor tape, and

[0040] - an optional cutter for cutting used capacitor tape.

[0041] According to a second aspect of the present disclosure, there is provided a method of controlling the aerosol generating system with a pair of electrically conductive rollers, comprising using the rollers to at least one of discharge and charge the capacitor to heat the electrolyte in the part of the capacitor that is received in the gap (or is in electrical and physical contact with the rollers or located in a heating space) and thereby generate an aerosol for inhalation by a user.

[0042] The method may further comprise rotating the rollers to feed the capacitor tape through the gap.

[0043] The aerosol generating system may further comprise any type of solid or semi-solid material downstream of the capacitor in an aerosol flow path. Example types of solid or semi-solid material include crumb, powder, granules, pellets, shreds, strands, particles, gel, strips, loose leaves, cut filler, porous material, foam material or sheets. The material may comprise plant derived material and in particular, may comprise tobacco material. The aerosol generated by heating the electrolyte of the capacitor will flow through the solid or semi-solid material, which may be positioned between the capacitor and a filter segment or mouthpiece through which the user inhales the aerosol, for example. The solid or semi-solid material may release one or more volatile compounds which may add flavour and nicotine to the aerosol, for example.

[0044] The aerosol that is inhaled by the user consists essentially of the vapourised or aerosolised electrolyte and optionally one or more volatile compounds that may be released by the separator material and / or the downstream solid or semi-solid material. The capacitor may comprise an electrically conductive wrapper. The wrapper may comprise appropriate perforations or openings, or incorporate a suitable aerosol- permeable membrane material, so that the aerosol generated when the electrolyte is heated may be freely inhaled by the user, while also preventing leakage of the electrolyte when in a liquid or gel state. The wrapper may comprise an electrically non- conductive substrate (e.g., a paper substrate) that is selectively doped with electrically conductive particles to make it electrically conductive. The wrapper may be doped with any suitable electrically conductive particles such as carbon-based or metal particles, for example. The wrapper may also be selectively impregnated with a suitable electrically conductive electrolyte such as sodium chloride-based electrolyte. The wrapper must be electrically conductive in at least the parts that extends next to the electrodes so that an electrical connection may be made with the electrically conductive rollers.

[0045] The capacitor may be pre-charged in the packaged article, i.e., it may already be charged when it is purchased by the user and before it is removably inserted into an aerosol generating device. Pre-charging the capacitor reduces the amount of energy that is required from the power source of the aerosol generating device for heating. This may lead to a reduction in the size and weight of the device.

[0046] The aerosol generating system may comprise an aerosol generating device adapted to receive, in use, the aerosol generating article described above. The aerosol generating device may comprise an external circuit (e.g., a switching circuit) that is electrically connected between the pair of rollers when the aerosol generating article including the capacitor is received in the device. The switching circuit may be configured to control the discharging of the capacitor. The switching circuit may optionally also be configured to control the charging of the capacitor from a power source of the aerosol generating device such as a battery. The switching circuit may include a switching device which may be controlled by a controller to selectively provide a continuous or switched (i.e., a discontinuous or intermittent) short circuit path between the pair of rollers that allows the electrical charge stored in the capacitor to be discharged through the switching circuit. The switching device may include one or more switches. The one or more switches may be semiconductor switching devices, which may be connected as a bridge circuit or a converter circuit, for example. The one or more switches may be opened or closed or switched on and off by a controller to provide the short circuit path.

[0047] The switching circuit may include a first terminal that is electrically connected to the first electrode of the capacitor through a first roller and a second terminal that is electrically connected to the second electrode of the capacitor through the second roller when the aerosol generating article is received in the aerosol generating device.

[0048] Discharging a pre-charged capacitor through an external circuit such as a switching circuit of the aerosol generating device will generate localised heat in the electrodes, which in turn heats the electrolyte contained in the electrodes and the porous separator. The localised heating is generated only in that part of the capacitor tape that is located in the heating space - e.g., which is received in the gap between the rollers. Sufficient localised heating of the electrolyte will generate an aerosol to be inhaled by the user during a vaping session. Using the external circuit to charge the capacitor will also generate localised heat in the electrodes, which in turn heats the electrolyte to generate an aerosol to be inhaled. When the electrolyte of a particular part of the capacitor tape has been consumed, the tape may be moved in the transport direction so that a new part of the tape is located in the heating space as described above.

[0049] The discharging and / or charging of the capacitor, and hence the heating of the electrolyte, may be controlled using the switching circuit. When charging the capacitor, the amount of electrical power that is supplied to the rollers from the power source may be varied by the switching circuit so as to control the heating of the electrolyte.

[0050] The amount of electrolyte in the capacitor tape or the remaining number of puffs may be notified to the user, for example using any suitable visual, audible or haptic notifying means. The amount of capacitor tape that has been used may be estimated or determined based on the rotation of the rollers. For example, the number of times that the rollers have been rotated to move the capacitor tape in the transport direction is inversely proportional to the amount of electrolyte in the rest of the capacitor that is available to be vapourised or aerosolised and also to the remaining number of puffs.

[0051] Brief Description of the Drawings

[0052] Figure l is a diagrammatic cross-sectional view of a capacitor tape;

[0053] Figure 2 is a diagrammatic view of an aerosol generating article in the form of a cassette that incorporates the capacitor tape of Figure 1;

[0054] Figure 3 is a diagrammatic view of an aerosol generating assembly that forms part of an aerosol generating device;

[0055] Figure 4 is a diagrammatic view showing part of the aerosol generating assembly of Figure 3;

[0056] Figures 5A, 5B and 5C are diagrammatic views showing how capacitor tape is moved in a transport direction by rotating the rollers of the aerosol generating assembly of Figure 3;

[0057] Figure 6 is a diagrammatic view of an aerosol generating device;

[0058] Figure 7 is a diagrammatic view showing the cassette of Figure 2 inserted into a compartment of the aerosol generating device of Figure 6;

[0059] Figure 8 is a diagrammatic view showing an alternative cassette inserted into a compartment of the aerosol generating device of Figure 6; and

[0060] Figure 9 is a diagrammatic view showing an alternative cassette inserted into a compartment of the aerosol generating device of Figure 6.

[0061] Detailed Description of Embodiments

[0062] Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

[0063] Referring initially to Figure 1, an electric double-layer supercapacitor is formed as a flexible tape 10, e.g., as a long, narrow flexible strip with multiple layers. The capacitor tape 10 includes a first carbon-based electrode layer 12a that defines a positive electrode and a second carbon-based electrode layer 12b that defines a negative electrode. A porous separator layer 14 is sandwiched between the first and second carbon-based electrode layers 12a, 12b. The separator layer 14 may comprise a flavour source medium. The separator layer 14 may comprise a plant derived material and in particular may comprise a tobacco material, for example, a porous tobacco sheet, or it may comprise any suitable cellulose- or polypropylene-based material. When heated, the separator material may release one or more volatile compounds. The volatile compounds may include nicotine or flavour compounds such as tobacco or other flavouring.

[0064] As shown in Figure 2, a cassette 20 includes a housing body 22 made of a suitable plastics material. A length of the capacitor tape 10 is wound onto a supply spool 24 and a downstream end of the capacitor tape 10 is wound onto or connected to a waste spool 26. Both the supply spool 24 and the waste spool 26 are freely rotatable within the housing body 22 and are made of a suitable plastics material. The cassette 20 may also include guides 28 that ensure that the capacitor tape 10 is properly aligned within the housing body 22. The guides 28 may also be made of a suitable plastics material so that the cassette 20 preferably does not include any metal components.

[0065] As shown in Figure 3, an aerosol generating assembly 30 includes a pair of electrically conductive rollers 32a, 32b. The rollers 32a, 32b may be made of any suitable electrically conductive material, e.g., aluminium. The rollers 32a, 32b are mounted in parallel for counter rotation and define a gap 34 therebetween (sometimes called a “nip gap”) through which the capacitor tape 10 is received. In Figure 3, the first roller 32a is shown to be rotating in an anti -clockwise direction and the second roller 32b is shown to be rotating in a clockwise direction. The gap 34 is such that the part of the capacitor tape 10 that is received through the gap 34 is in electrical and physical contact with the rollers 32a, 32b. This is shown more clearly in Figures 4 and 5A to 5C.

[0066] The rollers 32a, 32b are biased towards each other to apply a clamping pressure to the capacitor tape 10 that is received in the gap. In Figure 3, the clamping pressure is indicated by the block arrows. As well as making sure that the rollers 32a, 32b are in direct physical contact with the capacitor tape 10, the clamping pressure is preferably applied at a level that will reduce the electrical resistance of the part of the capacitor tape 10 that is in electrical and physical contact with the rollers 32a, 32b so that it may be properly charged and / or discharged. This may avoid the need for further additives in the electrolyte to reduce electrical resistance. If the electrical resistance of the capacitor tape 10 is too high, an electric current will not flow and the electrolyte can normally only be aerosolised when a sufficiently high clamping pressure is applied by the rollers 32a, 32b. The clamping pressure is applied to the rollers 32a, 32b by compression springs 36a, 36b or other suitable biasing elements, for example.

[0067] The rollers 32a, 32b are driven to rotate by electric motors 38a, 38b. The electric motors 38a, 38b are controlled by a controller 40. The electric motors 38a, 38b receive power from a power source, e.g., a rechargeable battery 42. Alternatively, one of the electric motors 38a, 38b may be omitted. In this alternative embodiment, one of the rollers 32a, 32b is driven to rotate by the electric motor, and the other roller is passively driven to rotate by following the movement of the capacitor tape 10.

[0068] The aerosol generating assembly 30 includes a switching circuit 44. The switching circuit 44 is electrically connected between the rollers 32a, 32b and adapted to control the discharging of the capacitor tape 10, and optionally the charging of the capacitor tape from the rechargeable battery 42. The switching circuit 44 is electrically connected to the rollers 32a, 32b by a rotary electrical interface. More particularly, a positive terminal of the switching circuit 44 is electrically connected to the first roller 32a by a first slip ring assembly 46a and a negative terminal of the switching circuit 44 is electrically connected to the second roller 32b by a second slip ring assembly 46b. It will be understood that the rollers 32a, 32b define current collectors and that the capacitor tape 10 itself preferably does not contain any metal components so as to provide a fully sustainable solution when it is necessary to dispose of the used capacitor tape. The first roller 32a is a positive current collector and is in electrical contact with the positive electrode of the capacitor tape 10 defined by the first carbon-based electrode layer 12a. The second roller 32b is a negative current collector and is in electrical contact with the negative electrode of the capacitor tape 10 defined by the second carbon-based electrode layer 12b. As shown more clearly in Figure 4, a heating space 48 is provided between the rollers 32a, 32b. The part of the capacitor tape 10 that is received through the gap 34 between the rollers 32a, 32b, and which is therefore also located in the heating space 48, is heated when the capacitor tape 10 is charged and / or discharged as described in more detail below. This localised heating of the part of the capacitor tape 10 that is located in the heating space 48 generates aerosol which may be inhaled by the user. The electrolyte in the part of the capacitor tape 10 that is being heated may be partially or fully consumed to generate aerosol that is inhaled by the user in one or more puffs. It will be understood that the parts of the capacitor tape 10 that are located outside of the heating space 48 will not be significantly heated.

[0069] The rollers 32a, 32b are rotated to feed the capacitor tape 10 through the gap 34. In other words, because the rollers 32a, 32b are in physical contact with the capacitor tape 10, rotating the first roller 32a in the anti-clockwise direction and rotating the second roller 32b in the clockwise direction as shown in Figures 3, 4 and 5B will feed the capacitor tape 10 through the gap 34 in an indicated transport direction. Rotating the rollers 32a, 32b through a particular angle of rotation will move the capacitor tape 10 a particular distance in the transport direction. The rollers 32a, 32b are therefore used to selectively feed the capacitor tape 10 in the transport direction in response to user manipulation during a vaping session. For example, the rollers 32a, 32b may be rotated in response to a puff being detected, or after the user has taken one or more puffs. The controller 40 may vary the speed at which the capacitor tape 10 is fed through the gap 34 by controlling the rotation speed of the rollers 32a, 32b. The rotation speed of the rollers 32a, 32b may optionally be varied based on a characteristic of a detected puff. For example, the controller 40 may increase the rotation speed of the rollers 32a, 32b - and hence the speed at which the capacitor tape 10 is fed through the gap 34 - if a strong and / or a long puff is detected. Put another way, the rotation speed of the rollers 32a, 32b may be varied based on the strength and / or duration of the puff. This may ensure that a sufficient amount of aerosol is generated according to the particular puff characteristic. Alternatively or additionally, the controller 40 may control the charging rate and / or discharging rate of the capacitor tape 10 based on a characteristic of a detected puff. The charging rate and / or discharging rate may be controlled using the switching circuit 44. For example, the controller 40 may increase the charging rate or the discharging rate if a strong and / or a long puff is detected. This may also ensure that a sufficient amount of aerosol is generated according to the particular puff characteristic. Figure 5 A shows a first part 10A of the capacitor tape 10 located in the heating space. If the first part 10A contains enough electrolyte to generate enough aerosol for n puffs, where n is an integer, the capacitor tape 10 may be charged and / or discharged through the switching circuit 44 to generate localised heating of the first part 10A and generate enough aerosol for the user to take n puffs. Each puff may be detected by a suitable puff detector (not shown). After the user has taken n puffs, the rollers 32a, 32b are rotated to move the capacitor tape 10 a particular distance in the transport direction so that a second part 10B of the capacitor tape is now located in the heating space between the rollers 32a, 32b. The capacitor tape 10 may be charged and / or discharged through the switching circuit 44 to generate localised heating of the second part 10B and generate enough aerosol for the user to take n puffs. After the user has taken n puffs, the rollers 32a, 32b are rotated again to move the capacitor tape 10 a particular distance in the transport direction so that a third part of the capacitor tape is now located in the heating space between the rollers 32a, 32b, and so on. The capacitor tape 10 may be designed to provide a total number of puffs before all of the electrolyte in the capacitor tape 10 is consumed and it needs to be replaced. For example, if the capacitor tape 10 includes p sections, where p is an integer, and each section contains enough electrolyte for n puffs, the capacitor tape 10 may provide a total of (p x n) puffs before it needs to be replaced.

[0070] The switching circuit 44 may include a switching device which may be controlled by the controller 40 to selectively provide a continuous or switched (i.e., a discontinuous or intermittent) short circuit path between the rollers 32a, 32b that allows the electrical charge stored in the capacitor tape 10 to be discharged through the switching circuit 44. The switching device may include one or more switches. The one or more switches may be semiconductor switching devices. The one or more switches may be opened or closed or switched on and off by the controller 40 to provide the short circuit path. The switching circuit 44 may further include either a variable resistor, a resistor array or other suitable component such as a regulator for adjusting the rate at which the capacitor tape 10 is discharged and / or the rate at which the capacitor tape 10 is charged from the rechargeable battery 42. Discharging a pre-charged capacitor tape 10 through an external circuit such as a switching circuit 44 of the aerosol generating assembly 30 will generate localised heat in the electrode layers 12a, 12b, which in turn heats the electrolyte contained in the electrode layers and the separator layer 14. The localised heating is generated only in that part of the capacitor tape 10 that is located in the heating space 48. Sufficient localised heating of the electrolyte will generate an aerosol to be inhaled by the user during a vaping session. Using the switching circuit 44 to charge the capacitor tape 10 from the rechargeable battery 42 will also generate localised heat in the electrode layers 12a, 12b, which in turn heats the electrolyte to generate an aerosol to be inhaled. The discharging and / or charging of the capacitor tape 10, and hence the heating of the electrolyte, may be controlled using the switching circuit 44. When charging the capacitor tape 10, the power applied to the electrically conductive rollers 32a, 32b may be varied by the switching circuit 44 to control the localised heating of the electrolyte.

[0071] Figure 6 shows an aerosol generating device 100 with a main body 102 and a mouthpiece 104 through which generated aerosol is inhaled by the user. The main body 102 includes a compartment 106 for receiving the cassette 20 shown in Figure 2. The compartment 106 may be closed by a cover (not shown). The rollers 32a, 32b are located in the compartment 106. In Figure 6, the rollers 32a, 32b are shown spaced apart. This may make it easier to insert or remove the cassette 20. In particular, when inserting a cassette 20 into the compartment 106, having spaced rollers 32a, 32b may make it easier to pass the capacitor tape 10 through the gap between the rollers 32a, 32b. After the cassette 20 has been inserted into the compartment 106, the rollers 32a, 32b may be moved back to the position shown in Figures 7 to 9 where the rollers 32a, 32b are spaced apart by a smaller gap and are in direct contact with the capacitor tape 10 so that the capacitor tape 10 moves when the rollers 32a, 32b are rotated. It may be easier to remove the cassette 20 from the compartment 20 if the rollers 32a, 32b are not in direct contact with the capacitor tape 10 and are not applying a clamping pressure. The rollers 32a, 32b may therefore be moved to the position shown in Figure 6 preparatory to removing the cassette 20 from the compartment 106. Maintaining the rollers 32a, 32b in this spaced position also allows a replacement cassette 20 to be easily inserted. The other parts of the aerosol generating assembly 30 are not shown in Figures 6 to 9 for conciseness. A hub 50 is also located in the compartment 106 and is adapted to engage with the waste spool 26 of the cassette 10 when the cassette is located in the compartment 106 to rotate the waste spool 26. The hub 50 is rotated by an electric motor (not shown) controlled by the controller 40 of the aerosol generating assembly 30. Figure 7 shows the cassette 20 located in the compartment 106 of the aerosol generating device 100. It may be seen that the capacitor tape 10 is received through the gap 34 between the rollers 32a, 32b and the hub 50 is engaged with the waste spool 26. The waste spool 26 is driven to rotate by the hub 50 when the rollers 32a, 32b are rotated (or afterwards) to take up the used capacitor tape 10. The supply spool 24 is freely rotatable within the cassette 20 and will rotate to supply the capacitor tape 10 towards the rollers 32a, 32b when they are rotated. In the words, the capacitor tape 10 will be drawn from the supply spool by the rollers 32a, 32b as it is moved a particular distance in the transport direction.

[0072] Figure 8 shows an alternative cassette 20 A with a supply spool 24 but no waste spool. The main body 102 of the aerosol generating device 100 includes an opening 108. The capacitor tape 10 is fed from the rollers 32a, 32b through the opening 108 such that a downstream part of the capacitor tape extends beyond the opening 108 as shown in Figure 8. The aerosol generating device 100 includes a cutter 110 adjacent to the opening 108 that is adapted to cut away the downstream part of the capacitor tape 10. The cutter 110 may be activated automatically or manually. The position of the cutter 110 is not limited to the bottom side of the capacitor tape 10 and may be located at any suitable position, e.g., on the top side or the other side of the capacitor tape 10.

[0073] Figure 9 shows another alternative cassette 20B with a supply spool 24 but no waste spool. As the capacitor tape 10 is fed from the rollers 32a, 32b in the transport direction, the used capacitor tape is simply retained within the cassette 20B (or alternatively within the main body 102 of the aerosol generating device 100). The used capacitor tape 10 is then removed when the cassette 20B is removed from the compartment 106. When all of the electrolyte in the capacitor tape 10 has been substantially consumed, it is also possible to drive the rollers 32a, 32b to rotate in the opposite direction (i.e., so the first roller 32a rotates in the clockwise direction and the second roller 32b rotates in the anti-clockwise direction). This will move the capacitor tape 10 in a reverse direction. Rotating the supply spool 24 (e.g., using a hub similar to the hub 50 described above) allows the used capacitor tape 10 to be taken up on to the supply spool. Such an arrangement may not require a cassette, but simply a supply spool 24 that can be used to supply the capacitor tape to the rollers 32a, 32b as described above, and then take up the used capacitor tape. It would therefore only be necessary to insert the supply spool 24 into the aerosol generating device 100 and make sure that the downstream end of the capacitor tape 10 is received through the gap between the rollers 32a, 32b. When the capacitor tape 10 is fully used, it may be wound back onto the supply spool 24 and the supply spool may be removed and a new one inserted. The supply spool 24 may be freely rotatable when the capacitor tape 10 is being moved in the transport direction by the rollers 32a, 32b but driven to rotate (e.g., by the hub) when the used capacitor tape is being moved in the reverse direction. Alternatively, the supply spool 24 may be driven to rotate in both directions.

[0074] 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.

[0075] 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.

[0076] 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”.

Claims

Claims1. An aerosol generating system comprising a capacitor (10) formed as a flexible tape, the capacitor (10) comprising aerosolisable electrolyte which, when heated, generates an aerosol for inhalation by a user.

2. An aerosol generating system according to claim 1, wherein the capacitor (10) further comprises a pair of electrodes, each electrode comprising at least one carbonbased electrode layer (12a, 12b), and a porous separator (14) between the electrodes, wherein the porous separator optionally comprises a flavour source medium.

3. An aerosol generating system according to claim 1 or claim 2, further comprising a pair of electrically conductive rollers (32a, 32b), wherein the rollers (32a, 32b) are mounted in parallel for counter rotation and define a gap (34) therebetween through which the capacitor (10) is received in electrical and physical contact with the rollers (32a, 32b).

4. An aerosol generating system according to claim 3, wherein the rollers (32a, 32b) are biased towards each other to apply a clamping pressure to the capacitor (10).

5. An aerosol generating system according to claim 3 or claim 4, wherein at least one of the rollers (32a, 32b) is adapted to be driven to rotate to feed the capacitor (10) through the gap (34).

6. An aerosol generating system according to claim 5, wherein at least one of the rollers (32a, 32b) is adapted to be driven to rotate in response to user manipulation of the aerosol generating system.

7. An aerosol generating system according to any of claims 3 to 6, further comprising a switching circuit (44) electrically connected between the pair of rollers (32a, 32b) and adapted to control the discharging of the capacitor (10) and / or the charging of the capacitor (10) from a power source (42).

8. An aerosol generating system according to claim 7, wherein the switching circuit (44) is electrically connected to each roller (32a, 32b) by a rotary electrical interface (46a, 46b).

9. An aerosol generating system according to claim 7 or claim 8, wherein the pair of rollers (32a, 32b) define current collectors, and the capacitor (10) does not comprise a current collector.

10. An aerosol generating system according to any of claims 3 to 9, wherein the capacitor (10) is supplied to the pair of rollers (32a, 32b) from an upstream supply spool (24).

11. An aerosol generating system according to any of claims 3 to 10, wherein the capacitor (10) is fed from the pair of rollers (32a, 32b) to a downstream waste spool (26) or where the downstream part of the capacitor (10) is captured inside a housing (102) of the aerosol generating system.

12. An aerosol generating system according to any of claims 3 to 10, further comprising a housing (102) with an opening (108), wherein the capacitor (10) is fed from the pair of rollers (32a, 32b) to the opening (108) such that a downstream part of the capacitor (10) extends beyond the opening (108), and wherein the system further comprises a cutter (110) adjacent the opening (108) adapted to cut away the downstream part of the capacitor (10).

13. An aerosol generating system according to any preceding claim, wherein the capacitor (10) is part of an aerosol generating article (20; 20A; 20B) and the aerosol generating system comprises an aerosol generating device (100) adapted to receive, in use, the aerosol generating article (20; 20A; 20B).

14. A method of controlling the aerosol generating system according to claim 3 comprising using the rollers (32a, 32b) to at least one of discharge and charge the capacitor (10) to heat the electrolyte in the part of the capacitor (10) that is received inthe gap (34), and is in electrical and physical contact with the rollers (32a, 32b), to thereby generate an aerosol for inhalation by a user.

15. A method according to claim 14, further comprising rotating at least one of the rollers (32a, 32b) to feed the capacitor (10) through the gap (34).

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