Patent ID: 12232533

DETAILED DESCRIPTION

Aspects and features of certain examples and embodiments are discussed/described herein. Some aspects and features of certain examples and embodiments may be implemented conventionally and these are not discussed/described in detail in the interests of brevity. It will thus be appreciated that aspects and features of apparatus and methods discussed herein which are not described in detail may be implemented in accordance with any conventional techniques for implementing such aspects and features.

As described above, the present disclosure relates to an aerosol provision system, such as an e-cigarette. Throughout the following description the term “e-cigarette” is sometimes used but this term may be used interchangeably with aerosol (vapor) provision system.

FIG.4is a schematic diagram illustrating an e-cigarette410in accordance with some embodiments of the disclosure (please note that the term e-cigarette is used herein interchangeably with other similar terms, such as electronic vapor provision system, electronic aerosol provision system, etc.). The e-cigarette410includes a control unit420and a cartridge430.FIG.4shows the control unit420assembled with the cartridge430(top), the control unit420by itself (middle), and the cartridge430by itself (bottom). Note that for clarity, various implementation details (e.g. such as internal wiring, etc.) are omitted.

As shown inFIG.4, the e-cigarette410has a generally cylindrical shape with a central, longitudinal axis (denoted as LA, shown in dashed line). Note that the cross-section through the cylinder, i.e. in a plane perpendicular to the line LA, may be circular, elliptical, square, rectangular, hexagonal, or some other regular or irregular shape as desired.

The mouthpiece435is located at one end of the cartridge430, while the opposite end of the e-cigarette410(with respect to the longitudinal axis) is denoted as the tip end424. The end of the cartridge430which is longitudinally opposite to the mouthpiece435is denoted by reference numeral431, while the end of the control unit420which is longitudinally opposite to the tip end424is denoted by reference numeral421.

The cartridge430is able to engage with and disengage from the control unit420by movement along the longitudinal axis LA. More particularly, the end431of the cartridge430is able to engage with, and disengage from, the end of the control unit421. Accordingly, ends421and431will be referred to as the control unit engagement end and the cartridge engagement end, respectively.

The control unit420includes a battery411and a circuit board415to provide control functionality for the e-cigarette410, e.g. by provision of a controller, processor, ASIC or similar form of control chip. The battery411is typically cylindrical in shape, and has a central axis that lies along, or at least close to, the longitudinal axis LA of the e-cigarette410. InFIG.4, the circuit board415is shown longitudinally spaced from the battery411, in the opposite direction to the cartridge430. However, the skilled person will be aware of various other locations for the circuit board415, for example, it may be at the opposite end of the battery411. A further possibility is that the circuit board415lies along the side of the battery411—for example, with the e-cigarette410having a rectangular cross-section, the circuit board415located adjacent one outer wall of the e-cigarette410, and the battery411then slightly offset towards the opposite outer wall of the e-cigarette410. Note also that the functionality provided by the circuit board415(as described in more detail below) may be split across multiple circuit boards and/or across devices which are not mounted to a PCB, and these additional devices and/or PCBs can be located as appropriate within the e-cigarette410.

The battery or cell411is generally re-chargeable, and one or more re-charging mechanisms may be supported. For example, a charging connection (not shown inFIG.4) may be provided at the tip end424, and/or the engagement end421, and/or along the side of the e-cigarette410. Moreover, the e-cigarette410may support induction re-charging of battery411, in addition to (or instead of) re-charging via one or more re-charging connections or sockets.

The control unit420includes a tube portion440, which extends along the longitudinal axis LA away from the engagement end421of the control unit420. The tube portion440is defined on the outside by outer wall442, which may generally be part of the overall outer wall or housing of the control unit420, and on the inside by inner wall424. A cavity426is formed by inner wall424of the tube portion440and the engagement end421of the control unit420. This cavity426is able to receive and accommodate at least part of a cartridge430as it engages with the control unit420(as shown in the top drawing ofFIG.4).

The inner wall424and the outer wall442of the tube portion440define an annular space which is formed around the longitudinal axis LA. A (drive or work) coil450is located within this annular space, with the central axis of the coil450being substantially aligned with the longitudinal axis LA of the e-cigarette410. The coil450is electrically connected to the battery411and circuit board415, which provide power and control to the coil450, so that in operation, the coil450is able to provide induction heating to the cartridge430.

The cartridge430includes a reservoir470containing liquid formulation (typically including nicotine). The reservoir470comprises a substantially annular region of the cartridge430, formed between an outer wall476of the cartridge430, and an inner tube or wall472of the cartridge430, both of which are substantially aligned with the longitudinal axis LA of the e-cigarette410. The liquid formulation may be held free within the reservoir470, or alternatively the reservoir470may incorporated in some structure or material, e.g. sponge, to help retain the liquid within the reservoir470.

The outer wall476has a portion476A of reduced cross-section. This allows this portion476A of the cartridge430to be received into the cavity426in the control unit420in order to engage the cartridge430with the control unit420. The remainder of the outer wall476has a greater cross-section in order to provide increased space within the reservoir470, and also to provide a continuous outer surface for the e-cigarette410—i.e. cartridge wall476is substantially flush with the outer wall442of the tube portion440of the control unit420. However, it will be appreciated that other implementations of the e-cigarette410may have a more complex/structured outer surface (compared with the smooth outer surface shown inFIG.4).

The inside of the inner tube472defines a passageway461which extends, in a direction of airflow, from air inlet461A (located at the end431of the cartridge430that engages the control unit420) through to air outlet461B, which is provided by the mouthpiece435. Located within the central passageway461, and hence within the airflow through the cartridge430, are heater455and wick454. As can be seen inFIG.4, the heater455is located approximately in the center of the drive coil450. In particular, the location of the heater455along the longitudinal axis LA can be controlled by having the step at the start of the portion476A of reduced cross-section for the cartridge430abut against the end (nearest the mouthpiece435) of the tube portion440of the control unit420(as shown in the top diagram ofFIG.4).

The heater455is made of a metallic material so as to permit use as a susceptor (or workpiece) in an induction heating assembly. More particularly, the induction heating assembly comprises the drive (work) coil450, which produces a magnetic field having high frequency variations (when suitably powered and controlled by the battery411and controller on PCB415). This magnetic field is strongest in the center of the coil450, i.e. within cavity426, where the heater455is located. The changing magnetic field induces eddy currents in the conductive heater455, thereby causing resistive heating within the heater element455. Note that the high frequency of the variations in magnetic field causes the eddy currents to be confined to the surface of the heater element455(via the skin effect), thereby increasing the effective resistance of the heater element455, and hence the resulting heating effect.

Furthermore, the heater element455is generally selected to be a magnetic material having a high permeability, such as (ferrous) steel (rather than just a conductive material). In this case, the resistive losses due to eddy currents are supplemented by magnetic hysteresis losses (caused by repeated flipping of magnetic domains) to provide more efficient transfer of power from the drive coil450to the heater element455.

The heater455is at least partly surrounded by wick454. Wick454serves to transport liquid from the reservoir470onto the heater455for vaporization. The wick454may be made of any suitable material, for example, a heat-resistant, fibrous material and typically extends from the passageway461through holes in the inner tube472to gain access into the reservoir470. The wick454is arranged to supply liquid to the heater455in a controlled manner, in that the wick454prevents the liquid leaking freely from the reservoir470into passageway461(this liquid retention may also be assisted by having a suitable material within the reservoir470itself). Instead, the wick454retains the liquid within the reservoir470, and on the wick454itself, until the heater455is activated, whereupon the liquid held by the wick454is vaporized into the airflow, and hence travels along passageway461for exit via mouthpiece435. The wick454then draws further liquid into itself from the reservoir470, and the process repeats with subsequent vaporizations (and inhalations) until the cartridge430is depleted.

Although the wick454is shown inFIG.4as separate from (albeit encompassing) the heater element455, in some implementations, the heater element455and wick454may be combined together into a single component, such as a heating element455made of a porous, fibrous steel material which can also act as a wick454(as well as a heater). In addition, although the wick454is shown inFIG.4as supporting the heater element455, in other embodiments, the heater element455may be provided with separate supports, for example, by being mounted to the inside of tube472(instead of or in addition to being supported by the heater element455).

The heater455may be substantially planar, and perpendicular to the central axis of the coil450and the longitudinal axis LA of the e-cigarette, since induction primarily occurs in this plane. AlthoughFIG.4shows the heater455and wick454extending across the full diameter of the inner tube472, typically the heater455and wick454will not cover the whole cross-section of the air passage-way461. Instead, space is typically provided to allow air to flow through the inner tube472from inlet461A and around heater455and wick454to pick up the vapor produced by the heater455. For example, when viewed along the longitudinal axis LA, the heater455and wick454may have an “O” configuration with a central hole (not shown inFIG.4) to allow for airflow along the passageway461. Many other configurations are possible, such as the heater455having a “Y” or “X” configuration. (Note that in such implementations, the arms of the “Y” or “X” would be relatively broad to provide better induction).

AlthoughFIG.4shows the engagement end431of the cartridge430as covering the air inlet461A, this end of the cartomizer30may be provided with one or more holes (not shown inFIG.4) to allow the desired air intake to be drawn into passageway461. Note also that in the configuration shown inFIG.4, there is a slight gap422between the engagement end431of the cartridge430and the corresponding engagement end421of the control unit420. Air can be drawn from this gap422through air inlet461A.

The e-cigarette410may provide one or more routes to allow air to initially enter the gap422. For example, there may be sufficient spacing between the outer wall476A of the cartridge430and the inner wall444of tube portion440to allow air to travel into gap422. Such spacing may arise naturally if the cartridge430is not a tight fit into the cavity426. Alternatively one or more air channels may be provided as slight grooves along one or both of these walls476A,444to support this airflow. Another possibility is for the housing of the control unit420to be provided with one or more holes, firstly to allow air to be drawn into the control unit420, and then to pass from the control unit420into gap422. For example, the holes for air intake into the control unit420might be positioned as indicated inFIG.4by arrows428A and428B, and engagement end421might be provided with one or more holes (not shown inFIG.4) for the air to pass out from the control unit420into gap422(and from there into the cartridge430). In other implementations, gap422may be omitted, and the airflow may, for example, pass directly from the control unit420through the air inlet461A into the cartridge430.

The e-cigarette410may be provided with one or more activation mechanisms for the induction heater assembly, i.e. to trigger operation of the drive coil450to heat the heating element455. One possible activation mechanism is to provide a button429on the control unit420, which a user may press to active the heater455. This button429may be a mechanical device, a touch sensitive pad, a sliding control, etc. The heater455may stay activated for as long as the user continues to press or otherwise positively actuate the button429, subject to a maximum activation time appropriate to a single puff of the e-cigarette410(typically a few seconds). If this maximum activation time is reached, the controller may automatically de-activate the induction heater455to prevent over-heating. The controller may also enforce a minimum interval (again, typically for a few seconds) between successive activations.

The induction heater assembly may also be activated by airflow caused by a user inhalation. In particular, the control unit420may be provided with an airflow sensor for detecting an airflow (or pressure drop) caused by an inhalation. The airflow sensor is then able to notify the controller of this detection, and the induction heater455is activated accordingly. The induction heater455may remain activated for as long as the airflow continues to be detected, subject again to a maximum activation time as above (and typically also a minimum interval between puffs).

Airflow actuation of the heater455may be used instead of providing button429(which could therefore be omitted), or alternatively the e-cigarette410may require dual activation in order to operate—i.e. both the detection of airflow and the pressing of button429. This requirement for dual activation can help to provide a safeguard against unintended activation of the e-cigarette410.

It will be appreciated that the use of an airflow sensor generally involves an airflow passing through the control unit420upon inhalation, which is amenable to detection (even if this airflow only provides part of the airflow that the user ultimately inhales). If no such airflow passes through the control unit420upon inhalation, then button429may be used for activation, although it might also be possible to provide an airflow sensor to detect an airflow passing across a surface of (rather than through) the control unit420.

There are various ways in which the cartridge430may be retained within the control unit420. For example, the inner wall444of the tube portion440of the control unit420and the outer wall of reduced cross-section476A may each be provided with a screw thread (not shown inFIG.4) for mutual engagement. Other forms of mechanical engagement, such as a snap fit or a latching mechanism (perhaps with a release button or similar) may also be used. Furthermore, the control unit420may be provided with additional components to provide a fastening mechanism, such as described below.

In general terms, the attachment of the cartridge430to the control unit420for the e-cigarette410ofFIG.4is simpler than in the case of the e-cigarette10shown inFIGS.1-3. In particular, the use of induction heating for e-cigarette410allows the connection between the cartridge430and the control unit420to be mechanical only, rather than also having to provide an electrical connection with wiring to a resistive heater. Consequently, the mechanical connection may be implemented, if so desired, by using an appropriate plastic molding for the housing of the cartridge430and the control unit420; in contrast, in the e-cigarette10ofFIGS.1-3, the housings of the cartomizer30and the control unit20have to be somehow bonded to a metal connector. Furthermore, the connector of the e-cigarette10ofFIGS.1-3has to be made in a relatively precise manner to ensure a reliable, low contact resistance, electrical connection between the control unit20and the cartomizer30. In contrast, the manufacturing tolerances for the purely mechanical connection between the cartridge430and the control unit420of e-cigarette410are generally greater. These factors all help to simplify the production of the cartridge430and thereby to reduce the cost of this disposable (consumable) component.

Furthermore, conventional resistive heating often utilizes a metallic heating coil surrounding a fibrous wick, however, it is relatively difficult to automate the manufacture of such a structure. In contrast, an inductive heating element455is typically based on some form of metallic disk (or other substantially planar component), which is an easier structure to integrate into an automated manufacturing process. This again helps to reduce the cost of production for the disposable cartridge430.

Another benefit of inductive heating is that conventional e-cigarettes may use solder to bond power supply wires to a resistive heater coil. However, there is some concern that heat from the coil during operation of such an e-cigarette might volatize undesirable components from the solder, which would then be inhaled by a user. In contrast, there are no wires to bond to the inductive heater element455, and hence the use of solder can be avoided within the cartridge430. Also, a resistive heater coil as in a conventional e-cigarette generally comprises a wire of relatively small diameter (to increase the resistance and hence the heating effect). However, such a thin wire is relatively delicate and so may be susceptible to damage, whether through some mechanical mistreatment and/or potentially by local overheating and then melting. In contrast, a disk-shaped heater element455as used for induction heating is generally more robust against such damage.

FIGS.5and6are schematic diagrams illustrating an e-cigarette510in accordance with some other embodiments of the invention. To avoid repetition, aspects ofFIGS.5and6that are generally the same as shown inFIG.4will not be described again, except where relevant to explain the particular features ofFIGS.5and6. Note also that reference numbers having the same last two digits typically denote the same or similar (or otherwise corresponding) components acrossFIGS.4to6(with the first digit in the reference number corresponding to the Figure containing that reference number).

In the e-cigarette510shown inFIG.5, the control unit520is broadly similar to the control unit420shown inFIG.4, however, the internal structure of the cartridge530is somewhat different from the internal structure of the cartridge430shown inFIG.4. Thus rather than having a central airflow passage, as for e-cigarette410ofFIG.4, in which the liquid reservoir470surrounds the central airflow passage461, in the e-cigarette510ofFIG.5, the air passageway561is offset from the central, longitudinal axis (LA) of the cartridge. In particular, the cartridge530contains an internal wall572that separates the internal space of the cartridge530into two portions. A first portion, defined by internal wall572and one part of external wall576, provides a chamber for holding the reservoir570of liquid formulation. A second portion, defined by internal wall572and an opposing part of external wall576, defines the air passage way561through the e-cigarette510.

In addition, the e-cigarette510does not have a wick, but rather relies upon a porous heater element555to act both as the heating element (susceptor) and the wick to control the flow of liquid out of the reservoir570. The porous heater element may be made, for example, of a material formed from sintering or otherwise bonding together steel fibers.

The heater element555is located at the end of the reservoir570opposite to the mouthpiece535of the cartridge530, and may form some or all of the wall of the reservoir570chamber at this end. One face of the heater element555is in contact with the liquid in the reservoir570, while the opposite face of the heater element555is exposed to an airflow region538which can be considered as part of air passageway561. In particular, this airflow region538is located between the heater element555and the engagement end531of the cartridge530.

When a user inhales on mouthpiece435, air is drawn into the region538through the engagement end531of the cartridge530from gap522(in a similar manner to that described for the e-cigarette410ofFIG.4). In response to the airflow (and/or in response to the user pressing button529), the coil550is activated to supply power to heater555, which therefore produces a vapor from the liquid in reservoir570. This vapor is then drawn into the airflow caused by the inhalation, and travels along the passageway561(as indicated by the arrows) and out through mouthpiece535.

In the e-cigarette610shown inFIG.6, the control unit620is broadly similar to the control unit420shown inFIG.4, but now accommodates two (smaller) cartridges630A and630B. Each of these cartridges630A and630B is analogous in structure to the reduced cross-section portion476A of the cartridge420inFIG.4. However, the longitudinal extent of each of the cartridges630A and630B is only half that of the reduced cross-section portion476A of the cartridge420inFIG.4, thereby allowing two cartridges to be contained within the region in e-cigarette610corresponding to cavity426in e-cigarette410, as shown inFIG.4. In addition, the engagement end621of the control unit620may be provided, for example, with one or more struts or tabs (not shown inFIG.6) that maintain cartridges630A,630B in the position shown inFIG.6(rather than closing the gap region622).

In the e-cigarette610, the mouthpiece635may be regarded as part of the control unit620. In particular, the mouthpiece635may be provided as a removable cap or lid, which can screw or clip onto and off the remainder of the control unit620(or any other appropriate fastening mechanism can be used). The mouthpiece cap635is removed from the rest of the control unit635to insert a new cartridge or to remove an old cartridge, and then fixed back onto the control unit for use of the e-cigarette610.

The operation of the individual cartridges630A,630B in e-cigarette610is similar to the operation of cartridge430in e-cigarette410, in that each cartridge630A,630B includes a wick654A,654B extending into the respective reservoir670A,670B. In addition, each cartridge630A,630B includes a heating element655A,655B, accommodated in a respective wick654A,654B, and may be energized by a respective coil650A,650B provided in the control unit620. The heaters655A,655B vaporize liquid into a common passageway661that passes through both cartridges630A,630B and out through mouthpiece635.

The different cartridges630A,630B may be used, for example, to provide different flavors for the e-cigarette610. In addition, although the e-cigarette610is shown as accommodating two cartridges630A,630B, it will be appreciated that some devices may accommodate a larger number of cartridges. Furthermore, although cartridges630A and630B are the same size as one another, some devices may accommodate cartridges of differing size. For example, an e-cigarette may accommodate one larger cartridge having a nicotine-based liquid, and one or more small cartridges to provide flavor or other additives as desired.

In some cases, the e-cigarette610may be able to accommodate (and operate with) a variable number of cartridges. For example, there may be a spring or other resilient device mounted on control unit engagement end621, which tries to extend along the longitudinal axis towards the mouthpiece635. If one of the cartridges shown inFIG.6is removed, this spring would therefore help to ensure that the remaining cartridge(s) would be held firmly against the mouthpiece for reliable operation.

If an e-cigarette has multiple cartridges, one option is that these are all activated by a single coil that spans the longitudinal extent of all the cartridges. Alternatively, there may an individual coil650A,650B for each respective cartridge630A,630B, as illustrated in FIG.6. A further possibility is that different portions of a single coil may be selectively energized to mimic (emulate) the presence of multiple coils.

If an e-cigarette does have multiple coils for respective cartridges (whether really separate coils, or emulated by different sections of a single larger coil), then activation of the e-cigarette (such as by detecting airflow from an inhalation and/or by a user pressing a button) may energize all coils. The e-cigarettes410,510,610however support selective activation of the multiple coils, whereby a user can choose or specify which coil(s) to activate. For example, e-cigarette610may have a mode or user setting in which in response to an activation, only coil650A is energized, but not coil650B. This would then produce a vapor based on the liquid formulation in coil650A, but not coil650B. This would allow a user greater flexibility in the operation of e-cigarette610, in terms of the vapor provided for any given inhalation (but without a user having to physically remove or insert different cartridges just for that particular inhalation).

It will be appreciated that the various implementations of e-cigarette410,510and610shown inFIGS.4-6are provided as examples only, and are not intended to be exhaustive. For example, the cartridge design shown inFIG.5might be incorporated into a multiple cartridge device such as shown inFIG.6. The skilled person will be aware of many other variations that can be achieved, for example, by mixing and matching different features from different implementations, and more generally by adding, replacing and/or removing features as appropriate.

FIG.7is a schematic diagram of the main electronic components of the e-cigarettes410,510,610ofFIGS.4-6in accordance with some embodiments of the invention. With the exception of the heater element455, which is located in the cartridge430, the remaining elements are located in the control unit420. It will be appreciated that since the control unit420is a re-usable device (in contrast to the cartridge430which is a disposable or consumable), it is acceptable to incur one-off costs in relation to production of the control unit which would not be acceptable as repeat costs in relation to the production of the cartridge. The components of the control unit420may be mounted on circuit board415, or may be separately accommodated in the control unit420to operate in conjunction with the circuit board415(if provided), but without being physically mounted on the circuit board415itself.

As shown inFIG.7, the control unit420includes a re-chargeable battery411, which is linked to a re-charge connector or socket725, such as a micro-USB interface. This connector725supports re-charging of battery411. Alternatively, or additionally, the control unit420may also support re-charging of battery411by a wireless connection (such as by induction charging).

The control unit420further includes a controller715(such as a processor or application specific integrated circuit, ASIC), which is linked to a pressure or airflow sensor716. The controller715may activate the induction heating, as discussed in more detail below, in response to the sensor716detecting an airflow. In addition, the control unit420further includes a button429, which may also be used to activate the induction heating, as described above.

FIG.7also shows a comms/user interface718for the e-cigarette. This may comprise one or more facilities according to the particular implementation. For example, the user interface718may include one or more lights and/or a speaker to provide output to the user, for example to indicate a malfunction, battery charge status, etc. The interface718may also support wireless communications, such as Bluetooth or near field communications (NFC), with an external device, such as a smartphone, laptop, computer, notebook, tablet, etc. The e-cigarette may utilize this comms interface718to output information such as device status, usage statistics, etc., to the external device, for ready access by a user. The comms interface718may also be utilized to allow the e-cigarette to receive instructions, such as configuration settings entered by the user into the external device. For example, the user interface718and controller715may be utilized to instruct the e-cigarette to selectively activate different coils650A,650B (or portions thereof), as described above. In some cases, the comms interface718may use the work coil450to act as an antenna for wireless communications.

The controller715may be implemented using one or more chips as appropriate. The operations of the controller715are generally controlled at least in part by software programs running on the controller715. Such software programs may be stored in non-volatile memory, such as ROM, which can be integrated into the controller715itself, or provided as a separate component (not shown). The controller715may access the ROM to load and execute individual software programs as and when required.

The controller715controls the inductive heating of the e-cigarette by determining when the device is or is not properly activated - for example, whether an inhalation has been detected, and whether the maximum time period for an inhalation has not yet been exceeded. If the controller715determines that the e-cigarette is to be activated for vaping, the controller715arranges for the battery411to supply power to the inverter712. The inverter712is configured to convert the DC output from the battery411into an alternating current signal, typically of relatively high frequency—e.g. 1 MHz (although other frequencies, such as 5 kHz, 20 kHz, 80 KHz, or 300 kHz, or any range defined by two such values, may be used instead). This AC signal is then passed from the inverter to the work coil450, via suitable impedance matching (not shown inFIG.7) if so required.

The work coil450may be integrated into some form of resonant circuit, such as by combining in parallel with a capacitor (not shown inFIG.7), with the output of the inverter712tuned to the resonant frequency of this resonant circuit. This resonance causes a relatively high current to be generated in work coil450, which in turn produces a relatively high magnetic field in heater element455, thereby causing rapid and effective heating of the heater element455to produce the desired vapor or aerosol output.

FIG.7Aillustrates part of the control electronics for an e-cigarette610having multiple coils in accordance with some implementations (while omitting for clarity aspects of the control electronics not directly related to the multiple coils).FIG.7Ashows a power source782A (typically corresponding to the battery411and inverter712ofFIG.7), a switch configuration781A, and the two work coils650A,650B, each associated with a respective heater element655A,655B as shown inFIG.6(but not included inFIG.7A). The switch configuration781A has three outputs denoted A, B and C inFIG.7A. It is also assumed that there is a current path between the two work coils650A,650B.

In order to operate the induction heating assembly, two out of three of these outputs A, B, C are closed (to permit current flow), while the remaining output stays open (to prevent current flow). Closing outputs A and C activates both coils, and hence both heater elements655A,655B; closing A and B selectively activates just work coil650A; and closing B and C activates just work coil650B.

Although it is possible to treat work coils650A and650B just as a single overall coil (which is either on or off together), the ability to selectively energize either or both of work coils650A and650B, such as provided by the implementation ofFIG.7, has a number of advantages, including:a) choosing the vapor components (e.g. flavorants) for a given puff. Thus activating just work coil650A produces vapor just from reservoir670A; activating just work coil650B produces vapor just from reservoir670B; and activating both work coils650A,650B produces a combination of vapors from both reservoirs670A,670B.b) controlling the amount of vapor for a given puff. For example, if reservoir670A and reservoir670B in fact contain the same liquid, then activating both work coils650A,650B can be used to produce a stronger (higher vapor level) puff compared to activating just one work coil by itselfc) prolonging battery (charge) lifetime. As already discussed, it may be possible to operate the e-cigarette610ofFIG.6when it contains just a single cartridge, e.g.630B (rather than also including cartridge630A). In this case, it is more efficient just to energize the work coil650B corresponding to cartridge630B, which is then used to vaporize liquid from reservoir670B. In contrast, if the work coil650A corresponding to the (missing) cartridge630A is not energized (because this cartridge and the associated heater element650A are missing from e-cigarette610), then this saves power consumption without reducing vapor output.

Although the e-cigarette610ofFIG.6has a separate heater element655A,655B for each respective work coil650A,650B, in some implementations, different work coils may energize different portions of a single (larger) workpiece or susceptor. Accordingly, in such an e-cigarette610, the different heater elements655A,655B may represent different portions of the larger susceptor, which is shared across different work coils. Additionally (or alternatively), the multiple work coils650A,650B may represent different portions of a single overall drive coil, individual portions of which can be selectively energized, as discussed above in relation toFIG.7A.

FIG.7Bshows another implementation for supporting selectivity across multiple work coils650A,650B. Thus inFIG.7B, it is assumed that the work coils650A,650B are not electrically connected to one another, but rather each work coil650A,650B is individually (separately) linked to the power source782B via a pair of independent connections through switch configuration781B. In particular, work coil650A is linked to power source782B via switch connections A1and A2, and work coil650B is linked to power source782B via switch connections B1and B2. This configuration ofFIG.7Boffers similar advantages to those discussed above in relation toFIG.7A. In addition, the architecture ofFIG.7Bmay also be readily scaled up to work with more than two work coils.

FIG.7Cshows another implementation for supporting selectivity across multiple work coils, in this case three work coils denoted650A,650B and650C. Each work coil650A,650B,650C is directly connected to a respect power supply782C1,782C2and782C3. The configuration ofFIG.7may support the selective energization of any single work coil,650A,650B,650C, or of any pair of work coils at the same time, or of all three work coils650A,650B,650C at the same time.

In the configuration ofFIG.7C, at least some portions of the power supply782may be replicated for each of the different work coils650. For example, each power supply782C1,782C2,782C3may include its own inverter, but they may share a single, ultimate power source, such as battery411. In this case, the battery411may be connected to the inverters via a switch configuration analogous to that shown inFIG.7B(but for DC rather than AC current). Alternatively, each respective power line from a power supply782to a work coil650may be provided with its own individual switch, which can be closed to activate the work coil (or opened to prevent such activation). In this arrangement, the collection of these individual switches across the different lines can be regarded as another form of switch configuration.

There are various ways in which the switching ofFIGS.7A-7Cmay be managed or controlled. In some cases, the user may operate a mechanical or physical switch that directly sets the switch configuration. For example, e-cigarette610may include a switch (not shown inFIG.6) on the outer housing, whereby cartridge630A can be activated in one setting, and cartridge630B can be activated in another setting. A further setting of the switch may allow activation of both cartridges630A,630B together. Alternatively, the control unit610may have a separate button associated with each cartridge630A,630B, and the user holds down the button for the desired cartridge (or potentially both buttons if both cartridges should be activated). Another possibility is that a button or other input device on the e-cigarette may be used to select a stronger puff (and result in switching on both or all work coils). Such a button may also be used to select the addition of a flavor, and the switching might operate a work coil associated with that flavor—typically in addition to a work coil for the base liquid containing nicotine. The skilled person will be aware of other possible implementations of such switching.

In some e-cigarettes, rather than direct (e.g. mechanical or physical) control of the switch configuration, the user may set the switch configuration via the comms/user interface718shown inFIG.7(or any other similar facility). For example, this interface718may allow a user to specify the use of different flavors or cartridges (and/or different strength levels), and the controller715can then set the switch configuration781according to this user input.

A further possibility is that the switch configuration may be set automatically. For example, e-cigarette610may prevent work coil650A from being activated if a cartridge is not present in the illustrated location of cartridge630A. In other words, if no such cartridge is present, then the work coil650A may not be activated (thereby saving power, etc).

There are various mechanisms available for detecting whether or not a cartridge is present. For example, the control unit620may be provided with a switch which is mechanically operated by inserting a cartridge into the relevant position. If there is no cartridge in position, then the switch is set so that the corresponding work coil is not powered. Another approach would be for the control unit to have some optical or electrical facility for detecting whether or not a cartridge is inserted into a given position.

Note that in some devices, once a cartridge has been detected as in position, then the corresponding work coil is always available for activation—e.g. it is always activated in response to a puff (inhalation) detection. In other devices that support both automatic and user-controlled switch configuration, even if a cartridge has been detected as in position, a user setting (or such-like, as discussed above) may then determine whether or not the cartridge is available for activation on any given puff.

Although the control electronics ofFIGS.7A-7Chave been described in connection with the use of multiple cartridges, such as shown inFIG.6, they may also be utilized in respect of a single cartridge that has multiple heater elements. In other words, the control electronics is able to selectively energize one or more of these multiple heater elements within the single cartridge. Such an approach may still offer the benefits discussed above. For example, if the cartridge contains multiple heater elements, but just a single, shared reservoir, or multiple heater elements, each with its own respective reservoir, but all reservoirs containing the same liquid, then energizing more or fewer heater elements provides a way for a user to increase or decrease the amount of vapor provided with a single puff. Similarly, if a single cartridge contains multiple heater elements, each with its own respective reservoir containing a particular liquid, then energizing different heater elements (or combinations thereof) provides a way for a user to selectively consume vapors for different liquids (or combinations thereof).

In some e-cigarettes, the various work coils and their respective heater elements (whether implemented as separate work coils and/or heater elements, or as portions of a larger drive coil and/or susceptor) may all be substantially the same as one another, to provide a homogeneous configuration. Alternatively, a heterogeneous configuration may be utilized. For example, with reference to e-cigarette610as shown inFIG.6, one cartridge630A may be arranged to heat to a lower temperature than the other cartridge630B, and/or to provide a lower output of vapor (by providing less heating power). Thus if one cartridge630A contains the main liquid formulation containing nicotine, while the other cartridge630B contains a flavorant, it may be desirable for cartridge630A to output more vapor than cartridge630B. Also, the operating temperature of each heater element655may be arranged according to the liquid(s) to be vaporized. For example, the operating temperature should be high enough to vaporize the relevant liquid(s) of a particular cartridge, but typically not so high as to chemically break down (disassociate) such liquids.

There are various ways of providing different operating characteristics (such as temperature) for different combinations of work coils and heater elements, and thereby produce a heterogeneous configuration as discussed above. For example, the physical parameters of the work coils and/or heater elements may be varied as appropriate—e.g. different sizes, geometry, materials, number of coil turns, etc. Additionally (or alternatively), the operating parameters of the work coils and/or heater elements may be varied, such as by having different AC frequencies and/or different supply currents for the work coils.

The example embodiments described above have primarily focused on examples in which the heating element (inductive susceptor) has a relatively uniform response to the magnetic fields generated by the inductive heater drive coil in terms of how currents are induced in the heating element. That is to say, the heating element is relatively homogenous, thereby giving rise to relatively uniform inductive heating in the heating element, and consequently a broadly uniform temperature across the surface of the heating element surface. However, in accordance with some example embodiments of the disclosure, the heating element may instead be configured so that different regions of the heating element respond differently to the inductive heating provided by the drive coil in terms of how much heat is generated in different regions of the heating element when the drive coil is active.

FIG.8represents, in highly schematic cross-section, an example aerosol provision system (electronic cigarette)300which incorporates a vaporizer305that comprises a heating element (susceptor)310embedded in a surrounding wicking material/matrix. The heating element310of the aerosol provision system300represented inFIG.8comprises regions of different susceptibility to inductive heating, but apart from this many aspects of the configuration ofFIG.8are similar to, and will be understood from, the description of the various other configurations described herein. When the system300is in use and generating an aerosol, the surface of the heating element310in the regions of different susceptibility are heated to different temperatures by the induced current flows. Heating different regions of the heating element310to different temperatures can be desired in some implementations because different components of a source liquid formulation may aerosolize/vaporize at different temperatures. This means that providing a heating element (susceptor) with a range of different temperatures can help simultaneously aerosolize a range of different components in the source liquid. That is to say, different regions of the heating element can be heated to temperatures that are better suited to vaporizing different components of the liquid formulation.

Thus, the aerosol provision system300comprises a control unit302and a cartridge304and may be generally based on any of the implementations described herein apart from having a heating element310with a spatially non-uniform response to inductive heating.

The control unit302comprises a drive coil306in addition to a power supply and control circuitry (not shown inFIG.8) for driving the drive coil306to generate magnetic fields for inductive heating as discussed herein.

The cartridge304is received in a recess of the control unit302and comprises the vaporizer305comprising the heating element310, a reservoir312containing a liquid formulation (source liquid)314from which the aerosol is to be generated by vaporization at the heating element310, and a mouthpiece308through which aerosol may be inhaled when the system300is in use. The cartridge304has a wall configuration (generally shown with hatching inFIG.8) that defines the reservoir312for the liquid formulation314, supports the heating element310, and defines an airflow path through the cartridge304. Liquid formulation may be wicked from the reservoir312to the vicinity of the heating element310(more particular to the vicinity of a vaporizing surface of the heating element310) for vaporization in accordance with any of the approaches described herein. The airflow path is arranged so that when a user inhales on the mouthpiece308, air is drawn through an air inlet316in the body of the control unit302, into the cartridge304and past the heating element310, and out through the mouthpiece308. Thus a portion of liquid formulation314vaporized by the heating element310becomes entrained in the airflow passing the heating element310and the resulting aerosol exits the system300through the mouthpiece308for inhalation by the user. An example airflow path is schematically represented inFIG.8by a sequence of arrows318. However, it will be appreciated the exact configuration of the control unit302and the cartridge304, for example in terms of how the airflow path through the system300is configured, whether the system300comprises a re-useable control unit302and replaceable cartridge304assembly, and whether the drive coil306and heating element310are provided as components of the same or different elements of the system300, is not significant to the principles underlying the operation of a heating element310having a non-uniform induced current response (i.e. a different susceptibility to induced current flow from the drive coil306in different regions) as described herein.

Thus, the aerosol provision system300schematically represented inFIG.8comprises in this example an inductive heating assembly comprising the heating element310in the cartridge304part of the system300and the drive coil306in the control unit302part of the system300. In use (i.e. when generating aerosol) the drive coil306induces current flows in the heating element310in accordance with the principles of inductive heating such as discussed elsewhere herein. This heats the heating element310to generate an aerosol by vaporization of an aerosol precursor material (e.g. liquid formation314) in the vicinity of a vaporizing surface the heating element310(i.e. a surface of the heating element310which is heated to a temperature sufficient to vaporize adjacent aerosol precursor material). The heating element310comprises regions of different susceptibility to induced current flow from the drive coil306such that areas of the vaporizing surface of the heating element310in the regions of different susceptibility are heated to different temperatures by the current flow induced by the drive coil306. As noted above, this can help with simultaneously aerosolizing components of the liquid formulation which vaporize/aerosolize at different temperatures. There are a number of different ways in which the heating element310can be configured to provide regions with different responses to the inductive heating from the drive coil306(i.e. regions which undergo different amounts of heating/achieve different temperatures during use).

FIGS.9A and9Bschematically represent respective plan and cross-section views of a heating element330comprising regions of different susceptibility to induced current flow in accordance with one example implementation of an embodiment of the disclosure. That is to say, in one example implementation of the system schematically represented inFIG.8, the heating element310has a configuration corresponding to the heating element330represented inFIGS.9A and9B. The cross-section view ofFIG.9Bcorresponds with the cross-section view of the heating element310represented inFIG.8(although rotated 90 degrees in the plane of the figure) and the plan view ofFIG.9Acorresponds with a view of the heating element330along a direction that is parallel to the magnetic field created by the drive coil306(i.e. parallel to the longitudinal axis of the aerosol provision system300). The cross-section ofFIG.9Bis taken along a horizontal line in the middle of the representation ofFIG.9A.

The heating element330has a generally planar form, which in this example is flat. More particularly, the heating element330in the example ofFIGS.9A and9Bis generally in the form of a flat circularly disc. The heating element330in this example is symmetric about the plane ofFIG.9Ain that it appears the same whether viewed from above or below the plane ofFIG.9A.

The characteristic scale of the heating element330may be chosen according to the specific implementation at hand, for example having regard to the overall scale of the aerosol provision system300in which the heating element330is implemented and the desired rate of aerosol generation. For example, in one particular implementation the heating element330may have a diameter of around 10 mm and a thickness of around 1 mm. In other examples the heating element330may have a diameter in the range 3 mm to 20 mm and a thickness of around 0.1 mm to 5 mm.

The heating element330comprises a first region331and a second region332comprising materials having different electromagnetic characteristics, thereby providing regions of different susceptibility to induced current flow. The first region331is generally in the form of a circular disc forming the center of the heating element330and the second region332is generally in the form of a circular annulus surrounding the first region331. The first and second regions may be bonded together or may be maintained in a press-fit arrangement. Alternatively, the first and second regions may not be attached to one another, but may be independently maintained in position, for example by virtue of both regions being embedded in a surrounding wadding/wicking material.

In the particular example represented inFIGS.9A and9B, it is assumed the first and second regions331,332comprise different compositions of steel having different susceptibilities to induced current flows. For example, the different regions may comprise different material selected from the group of copper, aluminum, zinc, brass, iron, tin, and steel, for example ANSI 304 steel.

The particular materials in any given implementation may be chosen having regard to the differences in susceptibility to induced current flow which are appropriate for providing the desired temperature variations across the heating element330when in use. The response of a particular heating element330configuration may be modeled or empirically tested during a design phase to help provide a heating element configuration having the desired operational characteristics, for example in terms of the different temperatures achieved during normal use and the arrangement of the regions over which the different temperatures occur (e.g., in terms of size and placement). In this regard, the desired operational characteristics, e.g. in terms the desired range of temperatures, may themselves be determined through modeling or empirical testing having regard to the characteristic and composition of the liquid formulation in use and the desired aerosol characteristics.

It will be appreciated the heating element330represented inFIGS.9A and9Bis merely one example configuration for a heating element comprising different materials for providing different regions of susceptibility to induced current flow. In other examples, the heating element may comprise more than two regions of different materials. Furthermore, the particular spatial arrangement of the regions comprising different materials may be different from the generally concentric arrangement represented inFIGS.9A and9B. For example, in another implementation the first and second regions may comprise two halves (or other proportions) of the heating element, for example each region may have a generally planar semi-circle form.

FIGS.10A and10Bschematically represents respective plan and cross-section views of a heating element340comprising regions of different susceptibility to induced current flow in accordance with another example implementation of an embodiment of the disclosure. The orientations of these views correspond with those ofFIGS.9A and9Bdiscussed above. The heating element340may comprise, for example, ANSI304steel, and / or another suitable material (i.e. a material having sufficient inductive properties and resistance to the liquid formulation), such as such as copper, aluminum, zinc, brass, iron, tin, and other steels.

The heating element340again has a generally planar form, although unlike the example ofFIGS.9A and9B, the generally planar form of the heating element340is not flat. That is to say, the heating element340comprises undulations (ridges/corrugations) when viewed in cross-section (i.e. when viewed perpendicular to the largest surfaces of the heating element340). These one or more undulation(s) may be formed, for example, by bending or stamping a flat template former for the heating element. Thus, the heating element340in the example ofFIGS.10A and10Bis generally in the form of a wavy circular disc which, in this particular example, comprises a single “wave”. That is to say, a characteristic wavelength scale of the undulation broadly corresponds with the diameter of the disc. However, in other implementations there may be a greater number of undulations across the surface of the heating element340. Furthermore, the undulations may be provided in different configurations. For example, rather than going from one side of the heating element340to the other, the undulation(s) may be arranged concentrically, for example comprising a series of circular corrugations/ridges.

The orientation of the heating element340relative to magnetic fields generated by the drive coil when the heating element is in use in an aerosol provision system are such that the magnetic fields will be generally perpendicular to the plane ofFIG.10Aand generally aligned vertically within the plane ofFIG.10B, as schematically represented by magnetic field lines B. The field lines B are schematically directed upwards inFIG.10B, but it will be appreciated the magnetic field direction will alternate between up and down (or up and off) for the orientation ofFIG.10Bin accordance with the time-varying signal applied to the drive coil306.

Thus, the heating element340comprises locations where the plane of the heating element340presents different angles to the magnetic field generated by the drive coil306.

For example, referring in particular toFIG.10B, the heating element340comprises a first region341in which the plane of the heating element340is generally perpendicular to the local magnetic field B and a second region342in which the plane of the heating element340is inclined with respect to the local magnetic field B. The degree of inclination in the second region342will depend on the geometry of the undulations in the heating element340. In the example ofFIG.10B, the maximum inclination is on the order of around45degrees or so. Of course it will be appreciated there are other regions of the heating element340outside the first region341and the second region342which present still other angles of inclination to the magnetic field.

The different regions of the heating element340oriented at different angles to the magnetic field created by the drive coil306provide regions of different susceptibility to induced current flow, and therefore different degrees of heating. This follows from the underlying physics of inductive heating whereby the orientation of a planar heating element to the induction magnetic field affects the degree of inductive heating. More particularly, regions in which the magnetic field is generally perpendicular to the plane of the heating element340will have a greater degree of susceptibility to induced currents than regions in which the magnetic field is inclined relative to the plane of the heating element340.

Thus, in the first region341the magnetic field is broadly perpendicular to the plane of the heating element340and so this region (which appears generally as a vertical stripe in the plan view ofFIG.10A) will be heated to a higher temperature than the second region342(which again appears generally as a vertical stripe in the plan view ofFIG.10A) where the magnetic field is more inclined relative to the plane of the heating element340. The other regions of the heating element340will be heated according to the angle of inclination between the plane of the heating element340in these locations and the local magnetic field direction.

The characteristic scale of the heating element340may again be chosen according to the specific implementation at hand, for example having regard to the overall scale of the aerosol provision system in which the heating element340is implemented and the desired rate of aerosol generation. For example, in one particular implementation the heating element340may have a diameter of around 10 mm and a thickness of around 1 mm. The undulations in the heating element340may be chosen to provide the heating element340with angles of inclination to the magnetic field from the drive coil306ranging from 90° (i.e. perpendicular) to around 10 degrees or so.

The particular range of angles of inclination for different regions of the heating element340to the magnetic field may be chosen having regard to the differences in susceptibility to induced current flow which are appropriate for providing the desired temperature variations (profile) across the heating element340when in use. The response of a particular heating element configuration (e.g., in terms of how the undulation geometry affects the heating element temperature profile) may be modeled or empirically tested during a design phase to help provide a heating element configuration having the desired operational characteristics, for example in terms of the different temperatures achieved during normal use and the spatial arrangement of the regions over which the different temperatures occur (e.g., in terms of size and placement).

FIGS.11A and11Bschematically represents respective plan and cross-section views of a heating element350comprising regions of different susceptibility to induced current flow in accordance with another example implementation of an embodiment of the disclosure. The orientations of these views correspond with those ofFIGS.9A and9Bdiscussed above. The heating element350may comprise, for example, ANSI 304 steel, and/or another suitable material such as discussed above.

The heating element350again has a generally planar form, which in this example is flat. More particularly, the heating element350in the example ofFIGS.11A and11Bis generally in the form of a flat circular disc having a plurality of openings therein. In this example the plurality of openings354comprise four square holes passing through the heating element350. The openings354may be formed, for example, by stamping a flat template former for the heating element350with an appropriately configured punch. The openings354are defined by walls which disrupts the flow of induced current within the heating element350, thereby creating regions of different current density. In this example the walls may be referred to as internal walls of the heating element350in that they are associated with opening/holes in the body of the susceptor (heating element). However, as discussed further below in relation toFIGS.12A and12B, in some other examples, or in addition, similar functionality can be provided by outer walls defining the periphery of a heating element350.

The characteristic scale of the heating element350may be chosen according to the specific implementation at hand, for example having regard to the overall scale of the aerosol provision system in which the heating element is implemented and the desired rate of aerosol generation. For example, in one particular implementation the heating element350may have a diameter of around 10 mm and a thickness of around 1 mm with the openings354having a characteristic size of around 2 mm. In other examples the heating element330may have a diameter in the range 3 mm to 20 mm and a thickness of around 0.1 mm to 5 mm, and the one or more openings354may have a characteristic size of around 10% to 30% of the diameter, but in some case may be smaller or larger.

The drive coil306in the configuration ofFIG.8will generate a time-varying magnetic field which is broadly perpendicular to the plane of the heating element350and so will generate electric fields to drive induced current flow in the heating element350which are generally azimuthal. Thus, in a circularly symmetric heating element, such as represented inFIG.9A, the induced current densities will be broadly uniform at different azimuths around the heating element350. However, for a heating element which comprises walls that disrupt the circular symmetry, such as the walls associated with the holes354in the heating element350ofFIG.11A, the current densities will not be broadly uniform at different azimuths, but will be disrupted, thereby leading to different current densities, hence different amounts of heating, in different regions of the heating element.

Thus, the heating element350comprises locations which are more susceptible to induced current flow because current is diverted by walls into these locations leading to higher current densities. For example, referring in particular toFIG.11A, the heating element350comprises a first region351adjacent one of the openings354and a second region352which is not adjacent one of the openings354. In general, the current density in the first region351will be different from the current density in the second region352because the current flows in the vicinity of the first region351are diverted/disrupted by the adjacent opening354. Of course it will be appreciated these are just two example regions identified for the purposes of explanation.

The particular arrangement of openings354that provide the walls for disrupting otherwise azimuthal current flow may be chosen having regard to the differences in susceptibility to induced current flow across the heating element350which are appropriate for providing the desired temperature variations (profile) when in use. The response of a particular heating element configuration (e.g., in terms of how the openings affect the heating element temperature profile) may be modeled or empirically tested during a design phase to help provide a heating element configuration having the desired operational characteristics, for example in terms of the different temperatures achieved during normal use and the spatial arrangement of the regions over which the different temperatures occur (e.g., in terms of size and placement).

FIGS.12A and12Bschematically represents respective plan and cross-section views of a heating element360comprising regions of different susceptibility to induced current flow in accordance with yet another example implementation of an embodiment of the disclosure. The heating element360may again comprise, for example, ANSI304steel, and/or another suitable material such as discussed above. The orientations of these views correspond with those ofFIGS.9A and9Bdiscussed above.

The heating element360again has a generally planar form. More particularly, the heating element360in the example ofFIGS.12A and12Bis generally in the form of a flat star-shaped disc, in this example a five-pointed star. The respective points of the star are defined by outer (peripheral) walls of the heating element360which are not azimuthal (i.e. the heating element360comprises walls extending in a direction which has a radial component). Because the peripheral walls of the heating element360are not parallel to the direction of electric fields created by the time-varying magnetic field from the drive coil306, they act to disrupt current flows in the heating element360in broadly the same manner as discussed above for the walls associated with the openings354of the heating element350shown inFIGS.11A and11B.

The characteristic scale of the heating element360may be chosen according to the specific implementation at hand, for example having regard to the overall scale of the aerosol provision system in which the heating element360is implemented and the desired rate of aerosol generation. For example, in one particular implementation the heating element360may comprise five uniformly spaced points extending from 3 mm to 5 mm from a center of the heating element360(i.e. the respective points of the star may have a radial extent of around 2 mm). In other examples the protrusions (i.e. the points of the star in the example ofFIG.12A) could have different sizes, for example they may extend over a range from 1 mm to 20 mm.

As discussed above, the drive coil306in the configuration ofFIG.8will generate a time-varying magnetic field which is broadly perpendicular to the plane of a the heating element360and so will generate electric fields to drive induced current flows in the heating element360which are generally azimuthal. Thus, for a heating element360which comprises walls that disrupt the circular symmetry, such as the outer walls associated with the points of the star-shaped pattern for the heating element360ofFIG.12A, or a more simple shape, such as a square or rectangle, the current densities will not be uniform at different azimuths, but will be disrupted, thereby leading to different amounts of heating, and hence temperatures, in different regions of the heating element360.

Thus, the heating element360comprises locations which have different induced currents as current flows are disrupted by the walls. Thus, referring in particular toFIG.12A, the heating element360comprises a first region361adjacent one of the outer walls and a second region362which is not adjacent one of the outer walls. Of course it will be appreciated these are just two example regions identified for the purposes of explanation. In general, the current density in the first region361will be different from the current density in the second region362because the current flows in the vicinity of the first region361are diverted/disrupted by the adjacent non-azimuthal wall of the heating element.

In a manner similar to that described for the other example heating element configurations having locations with differing susceptibility to induced current flows (i.e. regions with different responses to the drive coil in terms of the amount of induced heating), the particular arrangement for the heating element's peripheral walls for disrupting the otherwise azimuthal current flow may be chosen having regard to the differences in susceptibility which are appropriate for providing the desired temperature variations (profile) when in use. The response of a particular heating element configuration (e.g., in terms of how the non-azimuthal walls affect the heating element temperature profile) may be modeled or empirically tested during a design phase to help provide a heating element configuration having the desired operational characteristics, for example in terms of the different temperatures achieved during normal use and the spatial arrangement of the regions over which the different temperatures occur (e.g., in terms of size and placement).

It will be appreciated broadly the same principle underlies the operation of the heating element350represented inFIGS.11A and11Band the heating element360represented inFIGS.12A and12Bin that the locations with different susceptibilities to induced currents are provided by non-azimuthal edges/walls to disrupt current flows. The difference between these two examples is in whether the walls are inner walls (i.e. associated with holes in the heating element) or outer walls (i.e. associated with a periphery of the heating element). It will further be appreciated the specific wall configurations represented inFIGS.11A and12Aare provided by way of example only, and there are many other different configurations which provide walls that disrupt current flows. For example, rather than a star-shaped configuration such as represented inFIG.12A, in another example the sector may comprise slot openings363, e.g., extended inwardly from a periphery or as holes in the heating element as shown inFIG.12B. More generally, what is significant is that the heating element is provided with walls which are not parallel to the direction of electric fields created by the time-varying magnetic field. Thus, for a configuration in which the drive coil is configured to generate a broadly uniform and parallel magnetic field (e.g. for a solenoid-like drive coil), the drive coil extends along a coil axis about which the magnetic field generated by the drive coil is generally circularly symmetric, but the heating element has a shape which is not circularly symmetric about the coil axis (in the sense of not being symmetric under all rotations, although it may be symmetric under some rotations).

Thus, there has been described above a number of different ways in which a heating element in an inductive heating assembly of an aerosol provision system can be provided with regions of different susceptibility to induced current flows, and hence different degrees of heating, to provide a range of different temperatures across the heating element. As noted above, this can be desired in some scenarios to facilitate simultaneous vaporization of different components of a liquid formulation to be vaporized having different vaporization temperatures/characteristics.

It will be appreciated there are many variations to the approaches discussed above and many other ways of providing locations with different susceptibility to induced current flows.

For example, in some implementations the heating element may comprise regions having different electrical resistivity in order to provide different degrees of heating in the different regions. This may be provided by a heating element comprising different materials having different electrical resistivities. In another implementation, the heating element may comprise a material having different physical characteristics in different regions. For example, there may be regions of the heating element having different thicknesses in a direction parallel to the magnetic fields generated by the drive coil and / or regions of the heating element having different porosity.

In some examples, the heating element itself may be uniform, but the drive coil may be configured so the magnetic field generated when in use varies across the heating element such that different regions of the heating element in effect have different susceptibility to induced current flow because the magnetic field generated at the heating element when the drive coil is in use has different strengths in different locations.

It will further be appreciated that in accordance with various embodiments of the disclosure, a heating element having characteristics arranged to provide regions of different susceptibility to induced currents can be provided in conjunction with other vaporizer characteristics described herein, for example the heating element having different regions of susceptibility to induced currents may comprise a porous material arranged to wick liquid formulation from a source of liquid formulation by capillary action to replace liquid formulation vaporized by the heating element when in use and/or may be provided adjacent to a wicking element arranged to wick liquid formulation from a source of liquid formulation by capillary action to replace liquid formulation vaporized by the heating element when in use.

It will furthermore be appreciated that a heating element comprising regions having different susceptibility to induced currents is not restricted to use in aerosol provision systems of the kind described herein, but can be used more generally in an inductive heat assembly of any aerosol provision system. Accordingly, although various example embodiments described herein have focused on a two-part aerosol provision system comprising a re-useable control unit302and a replaceable cartridge304, in other examples, a heating element having regions of different susceptibility may be used in an aerosol provision system that does not include a replaceable cartridge, but is a disposable system or a refillable system. Similarly, although the various example embodiments described herein have focused on an aerosol provision system in which the drive coil is provided in the reusable control unit302and the heating element is provided in the replaceable cartridge304, in other implementations the drive coil may also be provided in the replaceable cartridge, with the control unit and cartridge having an appropriate electrical interface for coupling power to the drive coil.

It will further be appreciated that in some example implementations a heating element may incorporate features from more than one of the heating elements represented inFIGS.9to12. For example, a heating element may comprise different materials (e.g. as discussed above with reference toFIGS.9A and9B) as well as undulations (e.g. as discussed above with reference toFIGS.10A and10B), and so on for other combinations of features.

It will further be appreciated that whilst some the above-described embodiments of a susceptor (heating element) having regions that respond differently to an inductive heater drive coil have focused on an aerosol precursor material comprising a liquid formulation, heating elements in accordance with the principles described herein may also be used in association with other forms of aerosol precursor material, for example solid materials and gel materials.

Thus there has also been described an inductive heating assembly for generating an aerosol from an aerosol precursor material in an aerosol provision system, the inductive heating assembly comprising: a heating element; and a drive coil arranged to induce current flow in the heating element to heat the heating element and vaporize aerosol precursor material in proximity with a surface of the heating element, and wherein the heating element comprises regions of different susceptibility to induced current flow from the drive coil, such that when in use the surface of the heating element in the regions of different susceptibility are heated to different temperatures by the current flow induced by the drive coil.

FIG.13schematically represents in cross-section a vaporizer assembly500for use in an aerosol provision system, for example of the type described above, in accordance with certain embodiments of the present disclosure. The vaporizer assembly500comprises a planar vaporizer505and a reservoir502of source liquid504. The vaporizer505in this example comprises an inductive heating element506the form of a planar disk comprising ANSI 304 steel or other suitable material such as discussed above, surrounded by a wicking/wadding matrix508comprising a non-conducting fibrous material, for example a woven fiberglass material. The source liquid504may comprise an E-liquid formulation of the kind commonly used in electronic cigarettes, for example comprising 0-5% nicotine dissolved in a solvent comprising glycerol, water, and/or propylene glycol. The source liquid may also comprise flavorings. The reservoir502in this example comprises a chamber of free source liquid, but in other examples the reservoir502may comprise a porous matrix or any other structure for retaining the source liquid until such time that it is required to be delivered to the aerosol generator/vaporizer.

The vaporizer assembly500ofFIG.13may, for example, be part of a replaceable cartridge for an aerosol provision system of the kinds discussed herein. For example, the vaporizer assembly500represented inFIG.13may correspond with the vaporizer305and reservoir312of source liquid314represented in the example aerosol provision system300ofFIG.8. Thus, the vaporizer assembly500is arranged in a cartridge of an electronic cigarette so that when a user inhales on the cartridge/electronic cigarette, air is drawn through the cartridge and over a vaporizing surface of the vaporizer. The vaporizing surface of the vaporizer is the surface from which vaporized source liquid is released into the surrounding airflow, and so in the example ofFIG.13, is the left-most face of the vaporizer505. (It will be appreciated that references to “left” and “right”, and similar terms indicating orientation, are used to refer to the orientations represented in the figures for ease of explanation and are not intended to indicate any particular orientation is required for use.)

The vaporizer505is a planar vaporizer in the sense of having a generally planar/sheet-like form. Thus, the vaporizer505comprises first and second opposing faces connected by a peripheral edge wherein the dimensions of the vaporizer505in the plane of the first and second faces, for example a length or width of the vaporizer505faces, is greater than the thickness of the vaporizer505(i.e. the separation between the first and second faces), for example by more than a factor of two, more than a factor of three, more than a factor of four, more than a factor of five, or more than a factor of 10. It will be appreciated that although the vaporizer505has a generally planar form, the vaporizer505does not necessarily have a flat planar form, but could include bends or undulations, for example of the kind shown for the heating element340inFIG.10B. The heating element506part of the vaporizer505is a planar heating element in the same way as the vaporizer505is a planar vaporizer.

For the sake of providing a concrete example, the vaporizer assembly500schematically represented inFIG.13is taken to be generally circularly-symmetric about a horizontal axis through the center of, and in the plane of, the cross-section view represented inFIG.13, and to have a characteristic diameter of around 12 mm and a length of around 30 mm, with the vaporizer505having a diameter of around 11 mm and a thickness of around 2 mm, and with the heating element506having a diameter of around 10 mm and a thickness of around 1 mm. However, it will be appreciated that other sizes and shapes of vaporizer assembly500can be adopted according to the implementation at hand, for example having regard to the overall size of the aerosol provision system. For example, some other implementations may adopt values in the range of 10% to 200% of these example values.

The reservoir502for the source liquid (e-liquid)504is defined by a housing comprising a body portion (shown with hatching inFIG.13) which may, for example, comprise one or more plastic molded pieces, which provides a sidewall and end wall of the reservoir502whilst the vaporizer505provides another end wall of the reservoir502. The vaporizer505may be held in place within the reservoir housing body portion in a number of different ways. For example, the vaporizer505may be press-fitted and/or glued in the end of the reservoir housing body portion. Alternatively, or in addition, a separate fixing mechanism may be provided, for example a suitable clamping arrangement could be used.

Thus, the vaporizer assembly500ofFIG.13may form part of an aerosol provision system for generating an aerosol from a source liquid, the aerosol provision system comprising the reservoir502of source liquid504and the planar vaporizer505comprising the planar heating element506. By having the vaporizer505, and in particular in the example ofFIG.13, the wicking material508surrounding the heating element506, in contact with source liquid504in the reservoir502, the vaporizer505draws source liquid from the reservoir502to the vicinity of the vaporizing surface of the vaporizer505through capillary action. An induction heater coil of the aerosol provision system in which the vaporizer assembly500is provided is operable to induce current flow in the heating element506to inductively heat the heating element506and so vaporize a portion of the source liquid504in the vicinity of the vaporizing surface of the vaporizer505, thereby releasing the vaporized source liquid504into air flowing around the vaporizing surface of the vaporizer505.

The configuration represented inFIG.13in which the vaporizer505comprises a generally planar form comprising an inductively-heated generally planar heating element506and configured to draw source liquid504to the vaporizer's vaporizing surface provides a simple yet efficient configuration for feeding source liquid to an inductively heated vaporizer of the types described herein. In particular, the use of a generally planar vaporizer provides a configuration that can have a relatively large vaporizing surface with a relatively small thermal mass. This can help provide a faster heat-up time when aerosol generation is initiated, and a faster cool-down time when aerosol generation ceases. Faster heat-up times can be desired in some scenarios to reduce user waiting, and faster cool-down times can be desired in some scenarios to help avoid residual heat in the vaporizer from causing ongoing aerosol generation after a user has stopped inhaling. Such ongoing aerosol generation in effect represents a waste of source liquid and power, and can lead to source liquid condensing within the aerosol vision system.

In the example ofFIG.13, the vaporizer505includes the non-conductive porous material508to provide the function of drawing source liquid from the reservoir502to the vaporizing surface through capillary action. In this case the heating element506may, for example, comprise a nonporous conducting material, such as a solid disc. However, in other implementations the heating element506may also comprise a porous material so that it also contributes to the wicking of source liquid from the reservoir to the vaporizing surface. In the vaporizer505represented inFIG.13, the porous material508fully surrounds the heating element506. In this configuration the portions of porous material508to either side of the heating element506may be considered to provide different functionality. In particular, a portion of the porous material508between the heating element506and the source liquid504in the reservoir502may be primarily responsible for drawing the source liquid504from the reservoir502to the vicinity of the vaporizing surface of the vaporizer505, whereas the portion of the porous material508on the opposite side of the heating element506(i.e. to the left inFIG.13) may absorb source liquid504that has been drawn from the reservoir502to the vicinity of the vaporizing surface of the vaporizer505so as to store/retain the source liquid504in the vicinity of the vaporizing surface of the vaporizer505for subsequent vaporization.

Thus, in the example ofFIG.13, the vaporizing surface of the vaporizer505comprises at least a portion of the left-most face of the vaporizer505and source liquid504is drawn from the reservoir502to the vicinity of the vaporizing surface through contact with the right-most face of the vaporizer505. In examples where the heating element506comprises a solid material, the capillary flow of source liquid504to the vaporizing surface may pass through the porous material508at the peripheral edge of the heating element506to reach the vaporizing surface. In examples where the heating element506comprises a porous material, the capillary flow of source liquid504to the vaporizing surface may in addition pass through the heating element506.

FIG.14schematically represents in cross-section a vaporizer assembly510for use in an aerosol provision system, for example of the type described above, in accordance with certain other embodiments of the present disclosure. Various aspects of the vaporizer assembly510ofFIG.14are similar to, and will be understood from, correspondingly numbered elements of the vaporizer assembly500represented inFIG.13. However, the vaporizer assembly510differs from the vaporizer assembly500in having an additional vaporizer515provided at an opposing end of the reservoir512of source liquid504(i.e. the vaporizer505and the further vaporizer515are separated along a longitudinal axis of the aerosol provision system). Thus, the main body of the reservoir512(shown hatched inFIG.14) comprises what is in effect a tube which is closed at both ends by walls provided by a first vaporizer505, as discussed above in relation toFIG.13, and a second vaporizer515, which is in essence identical to the vaporizer505at the other end of the reservoir512. Thus, the second vaporizer515comprises a heating element516surrounded by a porous material518in the same way as the vaporizer505comprises a heating element506surrounded by a porous material508. The functionality of the second vaporizer515is as described above in connection withFIG.13for the vaporizer505, the only difference being the end of the reservoir504to which the vaporizer515is coupled. The approach ofFIG.14can be used to generate greater volumes of vapor since, with a suitably configured airflow path passing both vaporizers505,515, a larger area of vaporization surface is provided (in effect doubling the vaporization surface area provided by the single-vaporizer configuration ofFIG.13).

In configurations in which an aerosol provision system comprises multiple vaporizers, for example as shown inFIG.14, the respective vaporizers may be driven by the same or separate induction heater coils. That is to say, in some examples a single induction heater coil may be operable simultaneously to induce current flows in heating elements of multiple vaporizers, whereas in some other examples, respective ones of multiple vaporizers may be associated with separate and independently driveable induction heater coils, thereby allowing different ones of the multiple vaporizer to be driven independently of each other.

In the example vaporizer assemblies500,510represented inFIGS.13and14, the respective vaporizers505,515are fed with source liquid504in contact with a planar face of the vaporizer505,515. However, in other examples, a vaporizer may be fed with source liquid in contact with a peripheral edge portion of the vaporizer, for example in a generally annular configuration such as shown inFIG.15.

Thus,FIG.15schematically represents in cross-section a vaporizer assembly520for use in an aerosol provision system in accordance with certain other embodiments of the present disclosure. Aspects of the vaporizer assembly520shown inFIG.15which are similar to, and will be understood from, corresponding aspects of the example vaporizer assemblies represented in the other figures are not described again in the interest of brevity.

The vaporizer assembly520represented inFIG.15again comprises a generally planar vaporizer525and a reservoir522of source liquid524. In this example the reservoir522has a generally annular cross-section in the region of the vaporizer assembly520, with the vaporizer525mounted within the central part of the reservoir522, such that an outer periphery of the vaporizer525extends through a wall of the reservoir's housing (schematically shown hatched inFIG.15) so as to contact liquid524in the reservoir522. The vaporizer525in this example comprises an inductive heating element526the form of a planar annular disk comprising ANSI 304 steel, or other suitable material such as discussed above, surrounded by a wicking/wadding matrix528comprising a non-conducting fibrous material, for example a woven fiberglass material. Thus, the vaporizer525ofFIG.15broadly corresponds with the vaporizer505ofFIG.13, except for having a passageway527passing through the center of the vaporizer525through which air can be drawn when the vaporizer525is in use.

The vaporizer assembly520ofFIG.15may, for example, again be part of a replaceable cartridge for an aerosol provision system of the kinds discussed herein. For example, the vaporizer assembly520represented inFIG.15may correspond with the wick454, heating element455and reservoir470represented in the example aerosol provision system/e-cigarette410ofFIG.4. Thus, the vaporizer assembly520is a section of a cartridge of an electronic cigarette so that when a user inhales on the cartridge/electronic cigarette, air is drawn through the cartridge and through the passageway527in the vaporizer525. The vaporizing surface of the vaporizer525is the surface from which vaporized source liquid524is released into the passing airflow, and so in the example ofFIG.15, corresponds with surfaces of the vaporizer525which are exposed to the air path through the center of the vaporizer assembly520

For the sake of providing a concrete example, the vaporizer525schematically represented inFIG.15is taken to have a characteristic diameter of around 12 mm and a thickness of around 2 mm with the passageway527having a diameter of 2 mm. The heating element526is taken to have having a diameter of around 10 mm and a thickness of around 1 mm with a hole of diameter 4 mm around the passageway. However, it will be appreciated that other sizes and shapes of vaporizer can be adopted according to the implementation at hand. For example, some other implementations may adopt values in the range of 10% to 200% of these example values.

The reservoir522for the source liquid (e-liquid)524is defined by a housing comprising a body portion (shown with hatching inFIG.15) which may, for example, comprise one or more plastic molded pieces which provide a generally tubular inner reservoir wall in which the vaporizer525is mounted so the peripheral edge of the vaporizer525extends through the inner tubular wall of the reservoir housing to contact the source liquid524. The vaporizer525may be held in place with the reservoir housing body portion in a number of different ways. For example, the vaporizer525may be press-fitted and/or glued in the corresponding opening in the reservoir housing body portion. Alternatively, or in addition, a separate fixing mechanism may be provided, for example a suitable clamping arrangement may be provided. The opening in the reservoir housing into which the vaporizer525is received may be slightly undersized as compared to the vaporizer525so the inherent compressibility of the porous material528helps in sealing the opening in the reservoir housing against fluid leakage.

Thus, and as with the vaporizer assemblies ofFIGS.13and14, the vaporizer assembly522ofFIG.15may form part of an aerosol provision system for generating an aerosol from a source liquid comprising the reservoir522of source liquid524and the planar vaporizer525comprising the planar heating element526. By having the vaporizer525, and in particular in the example ofFIG.15, the porous wicking material528surrounding the heating element526, in contact with source liquid524in the reservoir522at the periphery of the vaporizer525, the vaporizer525draws source liquid524from the reservoir522to the vicinity of the vaporizing surface of the vaporizer525through capillary action. An induction heater coil of the aerosol provision system in which the vaporizer assembly520is provided is operable to induce current flow in the planar annular heating element526to inductively heat the heating element526and so vaporize a portion of the source liquid524in the vicinity of the vaporizing surface of the vaporizer525, thereby releasing the vaporized source liquid into air flowing through the central tube defined by the reservoir522and the passageway527through the vaporizer525.

The configuration represented inFIG.15in which the vaporizer525comprises a generally planar form comprising an inductively-heated generally planar heating element526and configured to draw source liquid524to the vaporizer vaporizing surface provides a simple yet efficient configuration for feeding source liquid to an inductively heated vaporizer of the types described herein having a generally annular liquid reservoir.

In the example ofFIG.15, the vaporizer525includes the non-conductive porous material528to provide the function of drawing source liquid524from the reservoir522to the vaporizing surface through capillary action. In this case the heating element526may, for example, comprise a nonporous material, such as a solid disc. However, in other implementations the heating element526may also comprise a porous material so that it also contributes to the wicking of source liquid524from the reservoir522to the vaporizing surface.

Thus, in the example ofFIG.15, the vaporizing surface of the vaporizer525comprises at least a portion of each of the left- and right-facing faces of the vaporizer525, and wherein source liquid524is drawn from the reservoir522to the vicinity of the vaporizing surface through contact with at least a portion of the peripheral edge of the vaporizer525. In examples, where the heating element526comprises a porous material, the capillary flow of source liquid524to the vaporizing surface may in addition pass through the heating element526.

FIG.16schematically represents in cross-section a vaporizer assembly530for use in an aerosol provision system, for example of the type described above, in accordance with certain other embodiments of the present disclosure. Various aspects of the vaporizer assembly530ofFIG.16are similar to, and will be understood from, corresponding elements of the vaporizer assembly520represented inFIG.15. However, the vaporizer assembly530differs from the vaporizer assembly520in having two vaporizers535A,535B provided at different longitudinal positions along a central passageway through a reservoir housing532containing source liquid534. The respective vaporizers535A,535B each comprise a heating element536A,536B surrounded by a porous wicking material538A,538B. The respective vaporizers535A,535B and the manner in which they interact with the source liquid534in the reservoir532may correspond with the vaporizer525represented inFIG.15and the manner in which that vaporizer525interacts with the source liquid524in the reservoir522. The functionality and purpose for providing multiple vaporizers535A,535B in the example represented inFIG.16may be broadly the same as discussed above in relation to the vaporizer assembly510comprising multiple vaporizers505,515represented inFIG.14.

FIG.17schematically represents in cross-section a vaporizer assembly540for use in an aerosol provision system, for example of the type described above, in accordance with certain other embodiments of the present disclosure. Various aspects of the vaporizer540ofFIG.17are similar to, and will be understood from, correspondingly numbered elements of the vaporizer assembly500represent inFIG.13. However, the vaporizer assembly540differs from the vaporizer assembly500in having a modified vaporizer545as compared to the vaporizer505ofFIG.13. In particular, whereas in the vaporizer505ofFIG.13the heating element506is surrounded by the porous material508on both faces, in the example ofFIG.17, the vaporizer545comprises a heating element546which is only surrounded by porous material548on one side, and in particular on the side facing the source liquid504in the reservoir502. In this configuration the heating element546comprises a porous conducting material, such as a web of steel fibers, and the vaporizing surface of the vaporizer is the outward facing (i.e. shown left-most inFIG.17) face of the heater element546. Thus, the source liquid504may be drawn from the reservoir502to the vaporizing surface of the vaporizer by capillary action through the porous material548and the porous heater element546. The operation of an electronic aerosol provision system incorporating the vaporizer ofFIG.17may otherwise be generally as described herein in relation to the other induction heating based aerosol provision systems.

FIG.18schematically represents in cross-section a vaporizer assembly550for use in an aerosol provision system, for example of the type described above, in accordance with certain other embodiments of the present disclosure. Various aspects of the vaporizer assembly550ofFIG.18are similar to, and will be understood from, correspondingly numbered elements of the vaporizer assembly500represented inFIG.13. However, the vaporizer assembly550differs from the vaporizer assembly500in having a modified vaporizer555as compared to the vaporizer505ofFIG.13. In particular, whereas in the vaporizer505ofFIG.13the heating element506is surrounded by the porous material508on both faces, in the example ofFIG.18, the vaporizer555comprises a heating element556which is only surrounded by porous material558on one side, and in particular on the side facing away from the source liquid504in the reservoir502. The heating element556again comprises a porous conducting material, such as a sintered/mesh steel material. The heating element556in this example is configured to extend across the full width of the opening in the housing of the reservoir502to provide what is in effect a porous seal and may be held in place by a press fit in the opening of the housing of the reservoir and/or glued in place and/or include a separate clamping mechanism. The porous material558in effect provides the vaporization surface for the vaporizer555. Thus, the source liquid504may be drawn from the reservoir502to the vaporizing surface of the vaporizer by capillary action through the porous heater element556. The operation of an electronic aerosol provision system incorporating the vaporizer ofFIG.18may otherwise be generally as described herein in relation to the other induction heating based aerosol provision systems.

FIG.19schematically represents in cross-section a vaporizer assembly560for use in an aerosol provision system, for example of the type described above, in accordance with certain other embodiments of the present disclosure. Various aspects of the vaporizer assembly560ofFIG.19are similar to, and will be understood from, correspondingly numbered elements of the vaporizer assembly500represented inFIG.13. However, the vaporizer assembly560differs from the vaporizer assembly500in having a modified vaporizer565as compared to the vaporizer505ofFIG.13. In particular, whereas in the vaporizer505ofFIG.13the heating element506is surrounded by the porous material508, in the example ofFIG.19, the vaporizer565consists of a heating element566without any surrounding porous material. In this configuration the heating element566again comprises a porous conducting material, such as a sintered/mesh steel material. The heating element566in this example is configured to extend across the full width of the opening in the housing of the reservoir502to provide what is in effect a porous seal and may be held in place by a press fit in the opening of the housing of the reservoir and/or glued in place and/or include a separate clamping mechanism. The heating element546in effect provides the vaporization surface for the vaporizer565and also provides the function of drawing source liquid504from the reservoir502to the vaporizing surface of the vaporizer by capillary action. The operation of an electronic aerosol provision system incorporating the vaporizer ofFIG.19may otherwise be generally as described herein in relation to the other induction heating based aerosol provision systems.

FIG.20schematically represents in cross-section a vaporizer assembly570for use in an aerosol provision system, for example of the type described above, in accordance with certain other embodiments of the present disclosure. Various aspects of the vaporizer assembly570ofFIG.20are similar to, and will be understood from, correspondingly numbered elements of the vaporizer assembly520represented inFIG.15. However, the vaporizer assembly570differs from the vaporizer assembly520in having a modified vaporizer575as compared to the vaporizer525ofFIG.15. In particular, whereas in the vaporizer525ofFIG.15the heating element526is surrounded by the porous material528, in the example ofFIG.20, the vaporizer575consists of a heating element576without any surrounding porous material. In this configuration the heating element576again comprises a porous conducting material, such as a sintered/mesh steel material. The periphery of the heating element576is configured to extend into a correspondingly sized opening in the housing of the reservoir522to provide contact with the liquid formulation and may be held in place by a press fit and/or glue and/or a clamping mechanism. The heating element546in effect provides the vaporization surface for the vaporizer575and also provides the function of drawing source liquid524from the reservoir522to the vaporizing surface of the vaporizer575by capillary action. The operation of an electronic aerosol provision system incorporating the vaporizer ofFIG.20may otherwise be generally as described herein in relation to the other induction heating based aerosol provision systems.

Thus,FIGS.13to20show a number of different example liquid feed mechanisms for use in an inductively heater vaporizer of an electronic aerosol provision system, such as an electronic cigarette. It will be appreciated these example set out principles that may be adopted in accordance with some embodiments of the present disclosure, and in other implementations different arrangements may be provided which include these and similar principles. For example, it will be appreciated the configurations need not be circularly symmetric, but could in general adopt other shapes and sizes according to the implementation hand. It will also be appreciated that various features from the different configurations may be combined. For example, whereas inFIG.15the vaporizer is mounted on an internal wall of the reservoir522, in another example, a generally annular vaporizer may be mounted at one end of a annular reservoir. That is to say, what might be termed an “end cap” configuration of the kind shown inFIG.13could also be used for an annular reservoir whereby the end-cap comprises an annular ring, rather than a non-annular disc, such as in the Example ofFIGS.13,14and17to19. Furthermore, it will be appreciated the example vaporizers ofFIGS.17,18,19and20could equally be used in a vaporizer assembly comprising multiple vaporizers, for example shown inFIGS.15and16.

It will furthermore be appreciated that vaporizer assemblies of the kind shown inFIGS.13to20are not restricted to use in aerosol provision systems of the kind described herein, but can be used more generally in any inductive heating based aerosol provision system. Accordingly, although various example embodiments described herein have focused on a two-part aerosol provision system comprising a re-useable control unit and a replaceable cartridge, in other examples, a vaporizer of the kind described herein with reference toFIGS.13to20may be used in an aerosol provision system that does not include a replaceable cartridge, but is a one-piece disposable system or a refillable system.

It will further be appreciated that in accordance with some example implementations, the heating element of the example vaporizer assemblies discussed above with reference toFIGS.13to20may correspond with any of the example heating elements discussed above, for example in relation toFIGS.9to12. That is to say, the arrangements shown inFIGS.13to20may include a heating element having a non-uniform response to inductive heating, as discussed above.

Thus, there has been described an aerosol provision system for generating an aerosol from a source liquid, the aerosol provision system comprising: a reservoir of source liquid; a planar vaporizer comprising a planar heating element, wherein the vaporizer is configured to draw source liquid from the reservoir to the vicinity of a vaporizing surface of the vaporizer through capillary action; and an induction heater coil operable to induce current flow in the heating element to inductively heat the heating element and so vaporize a portion of the source liquid in the vicinity of the vaporizing surface of the vaporizer. In some example the vaporizer further comprises a porous wadding/wicking material, e.g. an electrically non-conducting fibrous material at least partially surrounding the planar heating element (susceptor) and in contact with source liquid from the reservoir to provide, or at least contribute to, the function of drawing source liquid from the reservoir to the vicinity of the vaporizing surface of the vaporizer. In some examples the planar heating element (susceptor) may itself comprise a porous material so as to provide, or at least contribute to, the function of drawing source liquid from the reservoir to the vicinity of the vaporizing surface of the vaporizer.

In order to address various issues and advance the art, this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and to teach the claimed invention(s). It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilized and modifications may be made without departing from the scope of the claims. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. other than those specifically described herein, and it will thus be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims. The disclosure may include other inventions not presently claimed, but which may be claimed in future.