IDENTIFICATION RESISTANCE

The present invention relates to a method of manufacturing a cartridge for use with an aerosol-generating system, in particular for use with an e-cigarette. The cartridge is provided with an electrical resistor having a customizable electrical resistance which is indicative of the aerosol-forming medium stored in the cartridge.

Frequently used e-cigarettes have a modular construction and usually comprise a replaceable cartridge with a storage component for holding an aerosol-forming substrate. The aerosol-forming substrate comprised in the cartridge may vary considerably in composition, flavour, strength or other characteristics. Consumers may wish to interchange cartridges at will. However, the optimum vaporization conditions may depend on the composition of the aerosol-forming substrate comprised in the cartridges. Thus, in order to perfectly adapt the vaporization unit to the particular or specific aerosol-forming substrate chosen by the consumer, it would be desirable to include in the e-cigarettes automatic recognition means which can identify the replaceable cartridge or the aerosol-forming substrate stored therein, in order to automatically change the control settings of the vaporization equipment accordingly.

EP 2 399 636 A1 is directed to an aerosol generator comprising a replaceable cartridge as described above, wherein the cartridge comprises one or more electrical components for distinguishing the cartridge from other cartridges. The electrical components may be one or more electrical resistors, capacitances or inductances. The aerosol generator comprises means for determining the electrical resistance of the one or more electrical components. The aerosol generator may further comprise a look-up table stored in a memory unit, in which the characteristics of the electrical components are associated with data identifying the respective cartridge. In order to allow for distinguishing between different cartridges a plurality of electrical components may be used.

In the manufacturing method disclosed in EP 2 399 636 A1 and in other known manufacturing methods, the electrical components have to be provided to the cartridges during their assembly, and typically before the cartridges are filled with the aerosol-forming substrate. Thus, heretofore it is necessary to determine or pre-define the electrical components already during the assembly stage, and in any case before the respective aerosol-forming substrate is provided to the cartridge. This mandatory sequential manufacturing method reduces flexibility of the cartridge production process.

A further disadvantage of the conventional manufacturing technique is that a number of different electrical components, for example a number of different resistors, must be provided at the assembly place, in order to be able to equip the plurality of cartridges with their particular or specific and unambiguous combination of resistors during assembly. The present invention aims at overcoming the above mentioned problems, to simplify and to increase flexibility of conventional cartridge manufacturing processes.

According to a first aspect of the invention there is provided a method of manufacturing a cartridge suitable for use with an aerosol generating system. The method comprises the steps of providing a liquid storage portion, providing an electrical resistor having a pre-defined initial resistance, and mounting the electrical resistor to the cartridge. The electrical resistance of the electrical resistor is customized by physical manipulation, such that the resulting electrical resistance value is indicative of the aerosol-forming substrate comprised in the liquid storage portion.

In other words, the electrical resistance of the electrical resistor is customized by physical manipulation, such that the resulting particular or specific value of the electrical resistance is indicative of the aerosol-forming substrate comprised in the liquid storage portion.

Throughout this document the terms resistor, electrical resistor, or basic resistor may be used synonymously. The term basic resistor is used when it is desired to emphasize that the resistor is not yet customized.

The present invention significantly simplifies the production and manufacture of cartridges for aerosol-generating systems, as each cartridge is initially provided with an identical customizable basic resistor having a basic initial resistance. Thus, only one type of resistor is required as a basis, in order to produce a plurality of cartridges, wherein each type of cartridge or each type of aerosol-forming substrate comprised in the cartridge is defined by a particular or specific individual resistance value.

The electrical resistor may be made from any suitable material. Preferred materials are those materials that can easily be modified, for example a metallic sheet material, such as sheet material made from nichrome, aluminum, copper or any similar materials. The resistor may also be made from tungsten. Nichrome is useful because it can be manipulated easily, has relatively high resistivity, and is resistant to oxidation even at high temperatures. When materials are used that have lower resistivity, the dimensions of the resistors can still be selected to produce measurable differences in resistance when customized. The material may also be covered by a suitable covering layer in order to reduce exposure to air and oxidation.

The basic resistor provided to each cartridge may also have any suitable shape. The basic resistor may initially have a predefined geometrical shape, such as a rectangular, circular, semi-circular shape or any suitable combinations thereof.

The material of the basic resistor may be easily modified e.g. by physical means, such as by piercing, clipping, puncturing, cutting, stamping or deforming. Of course, the skilled person will readily appreciate that further methods may be suitable to modify the basic resistor. For example, material may be added to the basic resistor in order to customize its resistance. The additional material can be adjoined to the basic resistor by crimping, stamping or pressing. It is further possible to customize the basic resistor by printing a metal layer thereon using suitable stamping or painting techniques. The resistance can also be modified by applying a predefined amount of molten metal to its surface. Here in particular low melting metallic materials such as solder material may be used.

It is understood that the skilled person may also combine one or more customization techniques in order to modify and adjust the resistance of the basic resistor.

The electrical resistor may be mounted to the cartridge at any suitable position. The electrical resistor may be mounted on the inside of the cartridge, such that the resistor is not accessible by the consumer during normal replacement handling of the cartridge.

The electrical resistor may also be mounted on the outside of the cartridge, for example on an end face of the cartridge. By providing the electrical resistor at the outside of the cartridge, it is possible to customize the basic resistor at any time after the cartridge manufacturing process. Thus, manufacturing of the cartridge and customization of the basic resistor could be performed at completely different locations. Most conveniently customization can be performed at the filling location, directly before or after the cartridge is filled.

Thus, during manufacture each cartridge has an identical construction, independent from the actual type of aerosol-forming substrate that is to be provided in a subsequent filling step. This advantage considerably facilitates logistics during manufacture, because it is not necessary anymore to precisely define the exact numbers of each individual type of cartridges upon their manufacture. Instead, during manufacture all cartridges are equally provided with the same customizable basic resistor. The decision which cartridge has to be provided with which resistance is postponed until a decision is made which aerosol-forming substrate is filled into the respective cartridge. Thus, the overall production mode is even more efficient, because only a single type of cartridges is to be provided to the filling location, and the cartridges can then be customized to be provided with varying resistances after the decision is made which cartridge is filled with which aerosol-forming substrate.

In order to further protect the resistor from unwanted or inadvertent manipulation, the cartridge may further be provided with a cap which is adapted to cover the electrical resistor. In this way the electrical resistance is accessible for intentional customization, but is at the same time protected from manipulation, which ensures maximum safety for the consumers.

The cartridge may also comprise a heater element, which in use is connected to a power source and is controlled by the electric circuitry of the aerosol-generating system. The electrical contacts for contacting the electric heater and the electric resistor to the control circuitry may be provided as point contacts, rectangular contacts, circular contacts, or as concentric ring contacts. Small contact areas allow for a compact construction, but might require that the cartridge resumes a particular or specific orientation in order to close the contact. In contrast thereto, larger contact areas, in particular ring contacts, do not require a particular or specific orientation of the cartridge and therefore simplifies handling of the system for the consumers.

In a second aspect the invention is directed to a cartridge suitable for use with an aerosol generating system, wherein the cartridge comprises a liquid storage portion and an electrical resistor having a pre-defined initial resistance, wherein the electrical resistor is customizable by physical manipulation, such that the resulting electrical resistance value is indicative of the aerosol-forming substrate comprised in the liquid storage portion.

As mentioned for the first aspect, in other words the electrical resistor is customizable by physical manipulation, such that the resulting particular or specific value of the electrical resistance is indicative of the aerosol-forming substrate comprised in the liquid storage portion In a third aspect the invention is directed to an aerosol-generating system, in particular an e-cigarette, comprising the above mentioned cartridge, and a device portion, comprising a power supply and an electronic circuitry. The electronic circuitry is adapted to determine the electrical resistance of the customizable resistor, and to associate the electrical resistance with data identifying the cartridge.

The cartridge may be releasably mounted to the device portion of the aerosol- generating system.

The device portion may comprise a memory device for storing a look-up table, the lookup table comprising data representing the electrical resistance of the customized resistors, each electrical resistance value being associated with data identifying a cartridge.

Preferably, the look-up table may further comprise data representing one or more resistance values, each resistance value further associated with parameters representing a different energy profile to be applied to the heating element. Each resistance value is associated with a different cartridge identifier. This means that the aerosol generating system can be configured to deliver a constant amount, for example volume or mass of aerosol to the user even when cartridges containing different aerosol-forming substrates are inserted into the aerosol generating system.

For example, a particular aerosol-forming substrate contained within one cartridge may require more energy to be vaporized, than a different aerosol-forming substrate contained within another cartridge. By associating a resistance value or a particular cartridge identifier with a heating profile stored in a look-up table, a constant amount of aerosol can be delivered to the user independent of the type of aerosol-forming substrate stored in the cartridge.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 shows various possibilities of mounting the resistor to the cartridge;

Figure 2 shows an electronic circuit diagram for controlling the heater device and for identifying the cartridge of the present invention; Fig. 3 shows an embodiment of the invention in which the basic resistor is provided with a central slit of fixed width and varying length;

Fig. 4 shows a further embodiment of the invention in which the basic resistor is provided with central recesses of fixed length and varying width.

In Fig. 1 an example of a typically used aerosol generating system 10 is depicted. The aerosol generating system 10 of Fig. 1 is an electrically heated aerosol generating system 10 and comprises a two-part housing 12 having a device portion 14 and a cartridge 16. In the device portion 14, there is provided an electric power supply in the form of a battery 18 and an electric control circuitry 20. The cartridge 16 comprises a liquid storage portion 22 containing aerosol-forming substrate 24, a capillary wick 26 and a heating element in the form of a heating coil 28. In this embodiment the liquid storage portion 22 is a cylindrical structure defining a central air flow channel 30. The ends of the capillary wick 26 extend into the liquid storage portion 22. A central portion of the capillary wick 26 extends through the air flow channel 30 and is at least partially surrounded by the heating coil 28. The heating coil 28 is connected to the electric circuitry 20 via appropriate electrical connections (not shown). The housing 10 also includes an air inlet 32, and an air outlet 34 at the mouthpiece end.

In use, operation is as follows. Liquid aerosol-forming substrate 24 is transferred by capillary action from the liquid storage portion 22 from the ends of the wick 26 which extend into the liquid storage portion 22 to the central portion of the wick 26 which is surrounded by the heating coil 28. When a user draws on the device at the air outlet 34, ambient air is drawn through air inlet 32. A puff detection system (not shown) senses a puff and activates the heating coil 28. The battery 18 supplies electrical energy to the heating coil 28 to heat the central portion of the wick 26 surrounded by the heating coil 28. The aerosol-forming substrate 24 in the central portion of the wick 26 is vaporized by the heating coil 28 to create a supersaturated vapour. The supersaturated vapour is mixed with and carried in the air flow from the air inlet 32. In the air flow channel 30 the vapour condenses to form an inhalable aerosol, which is carried towards the outlet 34 and into the mouth of the user.

In addition to the above described elements a customizable resistor 40 is provided to the cartridge 16. The customizable resistor 40 is connected to the control circuitry 20 and allows the control circuitry 20 to identify the liquid storage portion 22 and in particular the type of aerosol-forming substrate 24 comprised in the liquid storage portion 22. As indicated in Figures 1 b to 1 d the customizable resistor 40 may be placed at various positions of the cartridge 16. In Fig. 1 b the customizable resistor 40 is placed in the liquid storage portion 22. In this embodiment the resistor 40 is not visible to the user and is protected from damage during normal handling of the aerosol generating system 10. However, in this embodiment the customization has to be carried out already during assembly of the cartridge 16. ln the embodiments of Figures 1 c and 1 d the customizable resistor 40 is provided at the end face of the cartridge 16 that is in use connected to the device part 14 of the aerosol generating system 10. In this embodiment the resistor 40 is still accessible after assembly of the cartridge 16. Thus, the resistor 40 can be customized at any time and it is not necessary to customize the resistor 40 already at the assembly stage. Instead, the resistor 40 may be customized after the cartridge 16 is filled with aerosol-forming substrate 24. During normal use, i.e. when the cartridge 16 is connected to the device part 14, the resistor 40 is not visible to the user. Thus, also in this embodiment and under normal handling conditions the resistor 40 is protected during use from accidental damage.

The customizable resistor 40 may take on various shapes. In Figures 1 b and 1 c the resistor is of rectangular sheet like shape. In Fig. 1 d the resistor has a largely circular shape. At the right hand sides of Figures 1 c and 1 d the resistor 40 is depicted before customization (without holes 42) and after customization (with holes 42).

The aerosol generating system 10 depicted in Fig. 1 is only one exemplary aerosol- generating system in which the cartridge of the present invention may advantageously be used. The skilled person will readily appreciate that the identification system of the present invention may also be used with other known designs of aerosol-generating systems 10 employing replaceable cartridges 16.

In Fig. 2 an electrical circuit diagram of an embodiment of the invention is depicted. In this embodiment, the heating device, e.g. heating coil 28, is connected to two electric contacts Ti , T2 which in turn are connected to the two contacts of the power source (not shown) provided in the aerosol generating system. In addition thereto, the circuit diagram of Fig. 2 shows a further electronic contact T3. The customizable resistor 40 is provided between contacts T2 and T3. The control circuitry 20 of the aerosol generating system 10 is adapted to determine the value of the customisable resistor 40 as discussed in the following.

As will be known to those skilled in the art, the voltage drop V across a resistor of resistance R is proportional to the product of the resistance R and the current I flowing through the resistor R. By measuring the magnitude or size of the electrical current passing through the resistor R for a given potential difference applied across resistor R, the controller circuitry is able to determine the value of the resistor R using the relationship R = V/l.

Having determined the value of resistor R associated with the cartridge, the control circuitry determines the cartridge type from the determined resistance value by searching a look-up table using the determined resistance value.

The look-up table may comprise one or more different resistance values, each resistance value associated with an identifier of a cartridge which can be used with the aerosol generating system. The identifier may be indicative of the type of liquid contained within the cartridge. The controller may determine the type of cartridge as the cartridge identifier stored in the look-up table which is associated with the resistance value stored in the look-up table which is closest in value to the cartridge resistance value determined by the controller. The look-up table may be stored in a read only memory (ROM) incorporated into the control circuitry or may be stored in a separate memory store.

In Fig. 3 one possible embodiment of a customizable resistor 40 is illustrated. In this embodiment the basic resistor 40 is a rectangular bar made from Nichrome, which is a material commonly used for resistors. Nichrome has an electrical resistivity of between 1 and 1 .5 x 10 ^{" 6} Ohms per meter. In the following calculations Nichrome is assumed to have an electrical resistivity of 1 x 10 ^"6 . The Nichrome bar has a length L of 10 millimetres, a thickness T of 1 millimetre and a width W of 3 millimetres. Thickness T and width W result define a cross- sectional area A of the bar of 3 square-millimetres. The resistance of the basic bar can be determined from its geometrical dimensions and the electrical resistivity according to the following formula:

Accordingly the resistance of the basic customizable resistor 40 amounts to 3,33 Ohms. Nichrome can be easily cut and punctured. As depicted in Fig. 3, the total resistance of the Nichrome bar can therefore be changed by cutting a hole 42 in the bar. In the embodiment of Fig. 3 a hole or slit 42 having a width of 1 millimetre is provided in the centre of the rectangular bar. The width of this hole 42 is kept constant, while the length of the hole 42 is varied. In this way a wide range of different resistance values can be obtained. The resulting resistances can be calculated by approximating the customized resistor 40 as being assembled from a plurality of individual resistors Ri , R2 as depicted in Fig. 3c, corresponding to the equivalent circuit diagram as depicted in Fig. 3d. The cross-sectional area of the resistors R2 amounts to 1 square-millimetre.

Using the known formulas for calculating the total resistance of serial or parallel connected resistors, the total resistance of the customized Nichrome bar can be calculated according to the following formulas:

1

R 2tot—

2

R2 R-2

Li L2 ¹ 2 \ A 2A ₂ J

The resulting total resistance values of the customized bar being provided with a hole 42 having a constant width of 1 millimetre and a varying length of 0 to 4 millimetres is given in the following table:

Table 1 : Resistor values for slits with varying length

It is important that the holes are exactly reproduced such that the electronic circuit is able to distinguish in a reliable way between the resistance values. The accuracy of the method for forming the hole in this case is preferably equal to, or better than +/- 5%.

As the rectangular bar is made from nichrome material, the shape of the bar can easily be modified by mechanical means. In the embodiment of Fig. 3 the hole may be punctured into the material by a suitable tool comprising a variety of punching bits for forming holes 42 of varying length. Customization of the plain resistor bar 40 can be performed at any time during manufacture of the cartridge 16. Advantageously, customization is performed after the decision is made which aerosol-forming substrate 24 is to be filled into the cartridge 16. Thus, customization is typically made after the aerosol-forming substrate is filled into the cartridge 16.

The electronic control circuit 20 determines the resistance value in order to verify the type of cartridge 16, and thus, the type of the aerosol-forming substrate 24 provided in the currently inserted cartridge 16. Having determined the type of the aerosol-forming substrate 24, the electronic control circuitry 20 can adjust the settings for activation of the heater device 28 to the particular or specific type of aerosol-forming substrate 24. In this way optimum vaporization conditions can be guaranteed for a wide variety of aerosol-forming substrates 24 usable with the aerosol generation system 10. ln Fig. 4 a further embodiment of a customizable resistor 40 is illustrated. In this embodiment the basic resistor 40 is again a rectangular bar made from Nichrome, having the same basic dimensions as the Nichrome bar illustrated in Fig. 3. In the embodiment of Fig. 4 two lateral recesses 44 are provided at the centres of the longitudinal edges of the rectangular bar. In this case, the length of the recesses 44 is 4 millimetres and is kept constant, while the depth of the recesses 44 is varied. In this way again a wide range of different resistance values can be obtained. The resulting resistances can be calculated by approximating the customized resistor 40 as being assembled from three serially connected resistors Ri, R2, Ri, as depicted in Fig. 4c, corresponding to the equivalent circuit diagram as depicted in Fig. 4d.

Using the above discussed formulas for calculating the total resistance of serially connected resistors, the resulting total resistance values of the customized bar being provided with recesses 44 having a constant length of 4 millimetres and a varying depth of 0 to 2 millimetres is given in the following table:

Table 2: Resistor values for recesses with varying depth

The same values are obtained, if a single recess 44 with double depth is provided on one longitudinal edge of the customizable resistor, as depicted in Fig. 4e.

Again, the electronic control circuit 20 determines the resistance value in order to verify the type of cartridge 16. Based thereon, the electronic control circuitry 20 can adjust the settings for activation of the heater device 28 to the particular or specific type of aerosol- forming substrate 24 used with the aerosol generation system 10.

The exemplary embodiments described above illustrate, but are not limiting. In view of the above discussed exemplary embodiments, other embodiments consistent with the above exemplary embodiments will now be apparent to one of ordinary skill in the art. For example, in the embodiment depicted in Fig. 3, it might also be possible to keep the length of the hole constant and to vary the width of the hole in order to change the electrical resistance of the customizable resistor. Further, additional holes or recesses, combinations of holes and recesses, or holes and recesses having other than rectangular shape may be used.