Cartridge for an aerosol generating system

Abstract

To provide a cartridge for an aerosol generation system.SOLUTION: A cartridge comprises: a housing for holding an aerosol formation substrate; a housing having an opening; and a heater assembly. The heater assembly includes at least one heater element which is fixed to the housing and extends over the opening of the housing. The at least one heater element defines a plurality of openings so that fluid can pass the at least one heater element and each of the plurality of openings has different size. A cartridge is also provided, in the cartridge, the at least one heater element comprises: an array of a conductive filament which extends along its length; and a plurality of transverse direction filaments which extends in a transverse direction with respect to the conductive filament. At least some of the transverse direction filaments extend only over a part of a width of the at least one heater element, and are deviated along the length of the at least one heater element.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an aerosol generation system and a cartridge for an aerosol generation system, the cartridge comprising a heater assembly suitable for vaporizing an aerosol-forming substrate. In particular, the present invention relates to a handheld aerosol generation system, such as an electrically operated smoking system. Aspects of the present invention relate to cartridges for aerosol generation systems and methods of manufacturing such cartridges.

Background Art

[0002] One type of aerosol generation system is an electrically operated smoking system. A handheld electrically operated smoking system is well known, which consists of a device portion comprising a battery and a control electronic circuit, a cartridge portion comprising a supply of an aerosol-forming substrate, and an electrically operated vaporizer. A cartridge comprising both a supply of an aerosol-forming substrate and a vaporizer is sometimes referred to as an "atomizer". The vaporizer is generally a heater assembly. In some well-known examples, the aerosol-forming substrate is a liquid aerosol-forming substrate and a vaporizer comprising a coil of heater wire wound around an elongated wick immersed in the liquid aerosol-forming substrate. The cartridge portion generally includes not only a supply of the aerosol-forming substrate and an electrically operated heater assembly, but also a mouthpiece through which the user draws in the aerosol into the mouth during use.

[0003] Accordingly, an electrically operated smoking system that vaporizes an aerosol-forming liquid by heating and forming an aerosol generally comprises a coil of wire wound around a capillary material that holds the liquid. The current passing through the wire causes resistive heating of the wire to vaporize the liquid within the capillary material. The capillary material is generally held within an air flow path such that air is drawn through the wick and mixed into the vapor. The vapor is then cooled to form an aerosol.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This type of system may be effective for aerosol generation, but may also be difficult to manufacture in a low-cost and repeatable manner. Furthermore, the wick and coil assembly, along with the associated electrical connections, can be fragile and difficult to handle.

[0005] It is desirable to provide a suitable cartridge for an aerosol generation system, such as a handheld electrically-operated smoking system having an inexpensive and robust heater assembly. It is further desirable to provide a cartridge for an aerosol generation system having a heater assembly that is as efficient as, or more efficient than, prior art heater assemblies of aerosol generation systems.

Means for Solving the Problem

[0006] According to a first aspect of the present invention, there is provided a cartridge for use in an aerosol generation system, the cartridge comprising a housing for holding an aerosol-forming substrate, the housing comprising a storage portion having an opening, and a heater assembly fixed to the housing and extending across the opening of the housing, the heater assembly comprising at least one heater element, at least one heater element of the heater assembly having a plurality of openings such that fluid can pass through the at least one heater element, and the plurality of openings having different sizes.

[0007] By providing at least one heater element having a plurality of openings such that fluid can pass through the at least one heater element, the at least one heater element is fluid-permeable. This means that the aerosol-forming substrate (which may be in the gas phase, but may also be in the liquid phase) can easily pass through the at least one heater element, and thus the heater assembly.

[0008] By varying the size of the opening, the flow of fluid through the heater element can be changed as desired, for example, to provide improved aerosol characteristics. For example, the amount of aerosol drawn through the heater assembly can be changed by using openings of different sizes.

[0009] As used herein, the terms "vary", "varies", "differ", "differs", and "different" refer to deviations that exceed standard manufacturing tolerances, particularly values that deviate from each other by at least five percent. This includes embodiments in which the sizes of most of the openings are substantially the same and a small number of openings, such as one or two openings, have different sizes, as well as embodiments in which an appropriate number of openings, such as at least five percent of the openings, have sizes that are different from the remaining openings, but is not limited thereto.

[0010] As used herein, "conductive" means being formed from a material having a resistivity of 1 × 10 -4 Ωm or less. As used herein, "insulative" means being formed from a material having a resistivity of 1 × 10 4 Ωm or more.

[0011] In certain preferred embodiments, the size of the apertures in the first region of the opening is larger than the size of the apertures in the second region of the opening. Advantageously, this allows the flow of fluid through at least one heater element, and thus through the heater assembly, to be selected as desired by arranging the first and second regions based on the characteristics of the aerosol generation system. For example, the size of the apertures in the first and second regions, or the relative positions of the first and second regions, can be selected based on the airflow characteristics of the aerosol generation system, the temperature profile of the heater assembly, or both. In some embodiments, the first region may be positioned towards the center of the opening relative to the second region. In other embodiments, the second region may be positioned towards the center of the opening relative to the first region.

[0012] The size of the apertures may vary gradually between the first and second regions of the opening. Alternatively, or additionally, the size of the apertures may increase stepwise between the first and second regions of the opening. When the size of the apertures varies gradually between the first and second regions of the opening, it is preferred that the apertures are formed by etching.

[0013] In some embodiments, the size of the apertures decreases towards the central portion of the opening. This arrangement results in a reduced flow of fluid through the central portion of the opening relative to the periphery of the opening. This can be advantageous depending on the temperature profile of the heater assembly or the airflow characteristics of the aerosol generation system for which the cartridge is intended. This includes embodiments where the size of the apertures decreases two-dimensionally, i.e., in both the height and width directions of the opening, towards the central portion of the opening, as well as embodiments where the size of the apertures decreases one-dimensionally only towards the central portion of the opening.

[0014] In some embodiments, the heater assembly comprises a plurality of heater elements extending across the width of the opening, and the heater element(s) extending closest to the central portion of the opening comprises a plurality of openings having a size smaller than the size of the openings of the other heater elements within the heater assembly. In a particular embodiment, the heater assembly comprises three heater elements extending across the width of the opening, and the central heater element comprises a plurality of openings having a size smaller than the size of the openings of the two outer heater elements.

[0015] In certain preferred embodiments, the size of the openings increases towards the central portion of the opening. In other words, the size of at least one opening towards the center of the opening is larger than the size of at least one opening further away from the center of the opening. This arrangement allows more aerosol to pass through the center of the openings of the heater element, and this can be advantageous in cartridges where the center of the opening is the most important vaporization zone, for example, cartridges where the temperature of the heater assembly is higher at the center of the opening. This includes embodiments where the size of the openings increases two-dimensionally, i.e., in both the height and width directions of the opening, towards the central portion of the opening, as well as embodiments where the size of the openings increases only one-dimensionally towards the central portion of the opening.

[0016] In some embodiments, the heater assembly comprises a plurality of heater elements extending across the width of the opening, and the heater element(s) extending closest to the central portion of the opening comprises a plurality of openings having a size larger than the size of the openings of the other heater elements within the heater assembly. In a particular embodiment, the heater assembly comprises three heater elements extending across the width of the opening, and the central heater element comprises a plurality of openings having a size larger than the size of the openings of the two outer heater elements.

[0017] As used herein, the term "central portion" of an opening refers to a part of the opening that is remote from the perimeter of the opening and has an area smaller than the total area of the opening. For example, the central portion may have an area less than about 80 percent of the total area of the opening, preferably less than about 60 percent, more preferably less than about 40 percent, and most preferably less than about 20 percent.

[0018] The plurality of openings may comprise a first set of openings having substantially the same size and one or more additional sets of openings having one or more smaller sizes. In such embodiments, the first set of openings may be located further from the central portion of the opening than one or more of the additional sets of openings. In alternative embodiments, the first set of openings may be located closer to the central portion of the opening than one or more additional sets of openings.

[0019] Alternatively, each of the openings may have a different size.

[0020] The sizes of the plurality of openings may gradually increase toward the center of the opening. Alternatively, or additionally, the sizes of the openings may increase stepwise toward the center of the opening.

[0021] In any of the above embodiments, the average size of the openings located in the central portion of the opening may be different from the average size of the openings outside the central portion of the opening. For example, the average size of the openings located in the central portion of the opening may be smaller than the average size of the openings outside the central portion of the opening. Preferably, the average size of the openings located in the central portion of the opening is larger than the average size of the openings outside the central portion of the opening. In certain preferred embodiments, the average size of the openings located in the central portion of the opening is at least 10 percent larger than the average size of the openings outside the central portion of the opening, preferably at least 20 percent larger, and more preferably at least 30 percent larger.

[0022] At least one heater element may comprise one or more sheets of conductive material, from which material is then removed, for example, to form a plurality of openings by stamping or etching. In a preferred embodiment, at least one heater element comprises an array of conductive filaments extending along the length of the at least one heater element, and the plurality of openings are defined by the gaps between the conductive filaments. In such embodiments, the size of the plurality of openings may vary by increasing or decreasing the size of the gaps between adjacent filaments. This may be achieved by varying the width of the conductive filaments, or by varying the spacing between adjacent filaments, or by varying both the width of the conductive filaments and the spacing between adjacent filaments.

[0023] Preferably, at least a portion of the heater element is spaced from the periphery of the opening through the gap at a distance greater than the dimension of the gap of that portion of the heater element.

[0024] As used herein, the term "filament" refers to an electrical path disposed between two electrical contacts. The filaments may optionally be branched or divided into several paths or filaments respectively, or may converge from several electrical paths into one path. The filaments may have a round, square, planar, or any other cross-sectional form. In a preferred embodiment, the filaments have a substantially planar cross-section. The filaments may be arranged linearly or curvilinearly.

[0025] The conductive filaments may be substantially planar. As used herein, "substantially planar" preferably means formed within a single plane and not, for example, wound or conformed around a curved shape or other non-planar shape. Planar heater assemblies are easy to handle during manufacturing and provide a robust structure.

[0026] The conductive filaments define a gap between the filaments. In certain embodiments, this gap has a width of from about 10 micrometers to about 100 micrometers, preferably having a width of from about 10 micrometers to about 60 micrometers. The filaments preferably cause capillary action within the gap such that, in use, a material, such as a liquid to be vaporized, is drawn into the gap, increasing the contact area between the heater assembly and the liquid.

[0027] The diameter of the conductive filaments may be from 8 micrometers to 100 micrometers, preferably from 8 micrometers to 50 micrometers, more preferably from 8 micrometers to 39 micrometers. The filaments may have a round cross-section or, for example, a flat cross-section. The conductive filaments are preferably substantially planar. When the conductive filaments are substantially planar, the term "diameter" refers to the width of the conductive filaments.

[0028] The conductive filaments may have different diameters. This may be done, for example, to vary the temperature profile of the heater element as desired, such as increasing the temperature of the heater element at the central portion of the aperture.

[0029] The area of the array of conductive filaments of a single heater element may be small, preferably 25 square millimeters or less, and can be incorporated into a handheld system. The heater element may, for example, be rectangular, having a length of about 5 millimeters and a width of about 2 millimeters. In some embodiments, the width is less than 2 millimeters, for example the width is about 1 millimeter. The narrower the width of the heater element, the more heater elements can be connected in series within the heater assembly of the present invention. The advantage of using heater elements with a narrower width connected in series is that the electrical resistance of the combination of heater elements increases.

[0030] The conductive filament may comprise any suitable conductive material. Suitable materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilicide, etc.), carbon, graphite, metals, alloys, and composite materials made of ceramic materials and metal materials. Such composite materials may include doped ceramics or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable alloys include stainless steels, constantan, nickel-, cobalt-, chromium-, aluminum-, titanium-, zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, and iron-containing alloys, and nickel, iron, cobalt, stainless steel-based superalloys, Timetal® (a registered trademark), iron-aluminum-based alloys, and iron-manganese-aluminum-based alloys. Timetal® is a registered trademark of Titanium Metals Corporation. The filament may be coated with one or more insulators. Preferred materials for the conductive filament are 304, 316, 304L, and 316L stainless steels, and graphite.

[0031] The conductive filaments may not be connected along each of their lengths and may be connected only at each end. Such an arrangement may result in a high level of electrical efficiency. In certain preferred embodiments, at least one heater element further comprises a plurality of transverse filaments extending in a transverse direction with respect to an array of conductive filaments, and thereby adjacent filaments in the array of conductive filaments are connected, and a plurality of openings are defined by the gaps between the conductive filaments and the gaps between the transverse filaments.

[0032] The cross - direction filaments increase the rigidity or structural stability of at least one heater element. This may reduce the risk of damage during assembly and use of at least one heater element. This improves the ease of assembly of the heater assembly and also improves the manufacturing reproducibility by reducing variations between different heater elements. Providing this type of heater assembly has several advantages over conventional core and coil arrangements. The heater assembly can be inexpensively manufactured using readily available materials and mass - production techniques. The heater assembly is robust and can be handled during manufacturing and fixed to other parts of the aerosol - generating system, and can in particular form a removable cartridge part.

[0033] The cross - direction filaments extend in any suitable cross - direction and may be substantially parallel to each other or not parallel. For example, the cross - direction filaments may be substantially parallel to each other or may be arranged at an angle of about 30 degrees to about 90 degrees from an array of conductive filaments. In certain embodiments, the cross - direction filaments are substantially parallel to each other and extend so as to be substantially perpendicular to an array of conductive filaments.

[0034] When at least one heater element comprises a plurality of cross - direction filaments, the gaps between the cross - direction filaments may be substantially constant and the size of the openings may vary by varying the size of the gaps between the filaments within the array of conductive filaments. The gaps between the cross - direction filaments preferably vary over at least the length, width, or length and width of the heater element such that the plurality of openings have different lengths. When the gaps between the cross - direction elements vary over at least the length of at least one heater element, this may be achieved by varying the width of the cross - direction filaments, or by varying the spacing between adjacent cross - direction filaments, or by varying both the width of the cross - direction filaments and the spacing between adjacent cross - direction filaments.

[0035] The diameter of the filament in the transverse direction may be from 8 micrometers to 100 micrometers, preferably from 8 micrometers to 50 micrometers, and more preferably from 8 micrometers to 39 micrometers. The filament in the transverse direction may have a round cross-section or, for example, a flat cross-section. The filament in the transverse direction is preferably substantially planar. When the filament in the transverse direction is substantially planar, the term "diameter" refers to the width of the conductive filament.

[0036] In a preferred embodiment, the conductive filament and the filament in the transverse direction have substantially the same diameter. In a preferred embodiment, both the conductive filament and the filament in the transverse direction are substantially planar.

[0037] One or more of the plurality of filaments in the transverse direction may extend across the entire width of the heater element. As another method, or additionally, at least some, preferably substantially all, of the plurality of filaments in the transverse direction extend only across a part of the width of at least one heater element. In such embodiments, two or more filaments in the transverse direction may be arranged in a coaxial relationship such that those filaments in the transverse direction extend together along a substantially straight line across at least the entire width of the heater element. In certain preferred embodiments, at least some, preferably substantially all, of the plurality of filaments in the transverse direction extend only across a part of the width of at least one heater element and are shifted along the length of at least one heater element. In other words, the continuous filaments in the transverse direction are shifted in the length direction of the heater element across the width of the heater element.

[0038] In certain preferred embodiments, at least a portion, preferably substantially all, of the plurality of transverse filaments extend across only a single gap between two conductive filaments and are offset along the length of the heater element. This arrangement reduces the spacing between successive transverse filaments along the length of each filament in the array and reduces the amount of each filament that is unsupported on either side. As a result, the length of the gaps and openings between adjacent transverse filaments can be increased without deleterious effects on the strength or rigidity of the heater element. This may be desirable to vary the fluid flow characteristics of the heater element and the aerosol delivery characteristics of the cartridge without deleterious effects on the rigidity or structural stability of the heater element.

[0039] The plurality of transverse filaments may be formed from any suitable material. For example, the plurality of transverse filaments may be formed from an electrically insulating material. In certain preferred embodiments, the transverse filaments are conductive. In such embodiments, the transverse filaments may be formed from any of the materials described above with respect to the array of conductive filaments. Preferably, the plurality of transverse filaments are formed from the same material as the array of conductive filaments.

[0040] In certain preferred embodiments, at least some, preferably substantially all, of the plurality of transverse filaments are conductive and extend across only a single gap between two conductive filaments and are offset along the length of the heater element. In this arrangement, the junctions between the filaments in the array and the transverse filaments each define three electrical paths. This is in contrast to conventional mesh heater elements where the junctions between the filaments each define four electrical paths. Without wishing to be bound by any particular theory, by reducing the number of transverse conductive elements and hence the number of electrical paths, the heater element of the present invention can better maintain the current direction across the heater element, resulting in a reduction in the variation of the temperature profile across the heater element area, leading to fewer high temperature spots, and this is thought to potentially reduce performance variation.

[0041] Furthermore, due to the transverse filaments being offset along the longitudinal direction.

[0042] According to a second aspect of the present invention, there is provided a cartridge for use in an aerosol generating system, which comprises a storage portion comprising a housing for holding an aerosol-forming substrate, the housing having an opening, the storage portion, and a heater assembly fixed to the housing and extending across the opening of the housing, the at least one heater element of the heater assembly comprising an array of conductive filaments extending along the length of the at least one heater element, and a plurality of transverse filaments extending in a direction transverse to the array of conductive filaments, thereby connecting adjacent filaments in the array of conductive filaments, the gaps between the conductive filaments and the gaps between the transverse filaments defining a plurality of openings so that fluid can pass through the at least one heater element, and at least a portion, preferably substantially all, of the plurality of transverse conductive filaments extending only over a portion of the width of the at least one heater element and being offset along the length of the at least one heater element.

[0043] This arrangement reduces the spacing between successive transverse filaments along the length of each filament in the array, reducing the amount of each filament that is unsupported on either side. As a result, the gaps between adjacent transverse filaments and the length of the openings can be increased without deleterious effects on the strength or rigidity of the heater element. This may enable the fluid flow characteristics of the heater element and the aerosol delivery characteristics of the cartridge to be varied as desired without deleterious effects on the rigidity or structural stability of the heater element.

[0044] The plurality of transverse filaments may be formed from any suitable material. For example, the plurality of transverse filaments may be formed from an electrically insulating material. In certain preferred embodiments, the transverse filaments are conductive. In such embodiments, the transverse filaments may be formed from any of the materials described above with respect to the array of conductive filaments. Preferably, the plurality of transverse filaments are formed from the same material as the array of conductive filaments.

[0045] In certain preferred embodiments, at least a portion, preferably substantially all, of the plurality of transverse filaments are conductive.

[0046] In this arrangement, the junctions between the filaments in the array and the transverse filaments each define three electrical paths. This is in contrast to conventional mesh heater elements where the junctions between the filaments each define four electrical paths. Without wishing to be bound by any particular theory, by reducing the number of transverse conductive elements, and thus the number of electrical paths, the heater element of the present invention can better maintain the current direction across the heater element, resulting in a reduction in the variation of the temperature profile across the heater element area, leading to fewer high temperature points, which may reduce performance variation.

[0047] One or more of the plurality of transverse conductive filaments may extend across the width of the heater element. In certain preferred embodiments, at least a portion, preferably substantially all, of the plurality of transverse filaments extend only across a single gap between two conductive filaments and are offset along the length of the heater element.

[0048] With this arrangement, along the length and for a given number of transverse filaments, the spacing between successive transverse filaments on either side of each filament in the array is reduced, so that the structural stability of at least one heater element can be increased or maintained using fewer transverse filaments. Consequently, the length of the gaps and openings between adjacent transverse filaments can be increased without a detrimental effect on the strength or rigidity of the heater element.

[0049] In any of the above embodiments in which the heater element comprises an array of conductive filaments and a plurality of transverse filaments, these filaments preferably each have a diameter of from about 8 micrometers to about 100 micrometers, more preferably from about 8 micrometers to about 50 micrometers, and even more preferably from about 8 micrometers to about 30 micrometers. The filaments may have a round cross-section or, for example, a flat cross-section. The conductive filaments and the transverse filaments are preferably substantially planar. When the filaments are substantially planar, the term "diameter" refers to the width of the filament. When the filaments are substantially planar, at least one heater element preferably comprises one or more sheets of conductive material from which the filaments are formed by, for example, stamping or etching away the material.

[0050] The conductive filaments, or the plurality of transverse filaments, or both may have different diameters. This may be the case when the temperature profile of the heater element is to be varied as desired, for example, to increase the temperature of the heater element at the central portion of the opening.

[0051] In any of the above embodiments, the plurality of apertures may have any suitable size or shape. In some embodiments, each of the plurality of apertures is elongated in the longitudinal direction of the heater element. Advantageously, by being elongated in the longitudinal direction of the heater element, the direction of the current through the heater element may be better maintained. In such embodiments, the plurality of apertures may each have a width of from about 10 micrometers to about 100 micrometers, and preferably have a width of from about 10 micrometers to about 60 micrometers. By using apertures having these approximate dimensions, a meniscus of the aerosol-forming substrate can be formed within the aperture, and the aerosol-forming substrate can be drawn by capillary action for the heater element of the heater assembly.

[0052] The cartridge comprises a storage portion having a housing for holding the aerosol-forming substrate, and the heater assembly includes at least one heater element fixed to the housing of the storage portion. The housing may be a rigid housing and may be impermeable to fluids. As used herein, "rigid housing" means a self-standing housing. The rigid housing of the storage portion preferably provides mechanical support for the heater assembly.

[0053] The housing of the storage portion may include a capillary material, and the capillary material may extend into the gaps between the filaments.

[0054] The capillary material may have a fibrous or spongy structure. The capillary material preferably includes a bundle of capillaries. For example, the capillary material may include a plurality of fibers or threads, or other fine tubes. The fibers or threads may generally be aligned to move liquid to the heater. Alternatively, the capillary material may include a sponge-like or foam-like material. The structure of the capillary material forms a plurality of small holes or tubes through which liquid can be transported by capillary action. The capillary material may include any suitable material or combination of materials. Examples of suitable materials include sponge or foam materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamed metal or plastic materials, such as fibrous materials made of spun or extruded fibers (cellulose acetate, polyester, or bonded polyolefins, polyethylene, terylene or polypropylene fibers, nylon fibers or ceramics, etc.). The capillary material may have any suitable capillary and porosity to be used with different liquid physical properties. The liquid has physical properties including, but not limited to, viscosity, surface tension, density, thermal conductivity, boiling point and vapor pressure that allow it to be transported through the capillary device by capillary action.

[0055] The capillary material may be in contact with the conductive filaments. The capillary material may extend into the gaps between the filaments. The heater assembly may draw the aerosol-forming substrate into the gaps by capillary action. The capillary material may be in contact with the conductive filaments substantially over the entire extent of the opening.

[0056] The housing may include two or more different capillary materials. The first capillary material in contact with at least one heater element has a higher thermal decomposition temperature, and the second capillary material in contact with the first capillary material but not in contact with at least one heater element has a lower thermal decomposition temperature. The first capillary material effectively serves as a spacer that separates the heater element from the second capillary material so that the second capillary material is not exposed to a temperature above its thermal decomposition temperature. As used herein, "thermal decomposition temperature" means the temperature at which the material begins to decompose and loses mass by generating gaseous by-products. The second capillary material may advantageously occupy a larger volume than the first capillary material and may hold more aerosol-forming substrate than the first capillary material. The second capillary material may have better wicking performance than the first capillary material. The second capillary material may be less expensive than the first capillary material or may have a high filling capacity. The second capillary material may be polypropylene.

[0057] The first capillary material may separate the heater assembly from the second capillary material by at least 1.5 millimeters, and preferably be between 1.5 millimeters and 2 millimeters in order to provide a sufficient temperature drop across the first capillary material.

[0058] The opening of the cartridge has dimensions of width and length. At least one heater element extends across the length dimension of the opening of the housing. The width dimension is the dimension perpendicular to the length dimension within the plane of the opening. It is preferred that at least one heater element of the heater assembly has a width narrower than the width of the opening of the housing.

[0059] It is preferred that a portion of the heater element passes through a gap with the peripheral portion of the opening. When the heater elements each comprise tabs attached to the housing at their respective ends, it is preferred that the sides of the tabs do not contact the housing. There is preferably a gap between the sides of the tabs and the peripheral portion of the opening.

[0060] The width of the heater element may be smaller than the width of the opening, at least in the region of the opening. The width of the heater element may be smaller than the width of the opening throughout the entire opening.

[0061] The width of at least one heater element of the heater assembly may be less than 90 percent, such as less than 50 percent, such as less than 30 percent, such as less than 25 percent of the width of the opening of the housing.

[0062] The area of at least one heater element may be less than 90 percent, such as less than 50 percent, such as less than 30 percent, such as less than 25 percent of the area of the opening of the housing. The area of the heater element of the heater assembly may be, for example, from 10 percent to 50 percent of the area of the opening, and preferably from 15 to 25 percent of the area of the opening.

[0063] The opening area of at least one heater element, which is the area ratio of the opening to the total area of the heater element, is preferably from about 25 percent to about 56 percent.

[0064] The heater element is preferably supported on an electrically insulated substrate. The insulating substrate preferably has an opening that defines the opening of the housing. The opening may be of any suitable shape. For example, the opening may have a circular, square, or rectangular shape. The area of the opening may be small and is preferably about 25 square millimeters or less.

[0065] The electrically insulated substrate may comprise any suitable material and is preferably a material that can withstand high temperatures (above 300 degrees Celsius) and rapid temperature changes. An example of a suitable material is a polyimide film such as Kapton (registered trademark). The electrically insulated substrate may be a flexible sheet material. The conductive contact portion and the conductive filament may be integrally formed with each other.

[0066] At least one heater element is preferably arranged such that the physical contact area with the base body is reduced as compared to the case where the heater elements of the heater assembly contact around the entire periphery of the opening. At least one heater element preferably does not directly contact the outer peripheral portion of the wall on the window side of the opening. In this way, the thermal contact with the base body is reduced, and the heat loss to the base body and further to the elements of the adjacent aerosol generation system is reduced.

[0067] Although not wishing to be bound by any particular theory, it is believed that spacing the heater element away from the housing opening results in less heat being transferred to the housing, and thus improves the efficiency of heating and, consequently, the efficiency of aerosol generation. When the heating element is close to or in contact with the peripheral portion of the opening, it is also considered that the material located at a position away from the opening is heated. Such heated material located away from the opening cannot be used for aerosol formation, so this heating is considered to be inefficient. By spacing the heating element away from the periphery of the opening in the housing, more efficient heating of the material or production of the aerosol may be obtained.

[0068] The spacing between the heater element and the periphery of the opening is preferably dimensioned such that the thermal contact is significantly reduced. The spacing between the heater element and the periphery of the opening may be from 25 micrometers to 40 micrometers.

[0069] The aerosol generation system may be an electrically operated smoking system.

[0070] The base body includes at least a first conductive contact portion and a second conductive contact portion for contacting at least one heater element. The first conductive contact portion and the second conductive contact portion are preferably positioned on opposite sides of the opening with respect to each other, and the first conductive contact portion and the second conductive contact portion are configured to be able to contact an external power source.

[0071] The heater assembly may comprise a single heater element or a plurality of heater elements connected in parallel. Preferably, the heater assembly comprises a plurality of heater elements connected in series. When the substrate comprises at least a first conductive contact portion and a second conductive contact portion for contacting at least one heater element, the first conductive contact portion and the second conductive contact portion may be arranged such that the first contact portion contacts the first heater element of the heater elements connected in series, and the second contact portion contacts the last heater element. Additional contact portions are provided in the heater assembly so that all the heater elements can be connected in series. Preferably, these additional contact portions are provided on each side of the opening of the substrate.

[0072] When the heater assembly includes a plurality of heater elements, the two or more heater elements may define a plurality of openings having substantially the same size. Alternatively or additionally, the heater assembly may comprise a first heater element defining a plurality of openings having a first size and a second heater element defining a plurality of openings having a second size, wherein the first size is different from the second size. For example, the heater assembly may comprise three heater elements, two of which define a plurality of openings having a first size and the remaining one of which defines a plurality of openings having a second size different from the first size. In some embodiments, the heater assembly includes a plurality of heater elements, each of which defines a plurality of openings having a size different from that of the other heater elements.

[0073] When the heater assembly includes a plurality of heater elements, the heater elements are preferably arranged spatially substantially parallel to each other. Preferably, there is a gap between the heater elements. Without wishing to be bound by any particular theory, it is believed that spacing the heater elements apart from each other may provide more efficient heating. By appropriately spacing the heater elements, for example, more uniform heating may be obtained over the area of the opening, compared to the case where a single heating element having the same area is used.

[0074] In a particularly preferred embodiment, the heater assembly comprises an odd number of heater elements, preferably three or five heater elements, and the first contact portion and the second contact portion are located on opposite sides of the opening of the substrate. This arrangement has the advantage that the first contact portion and the second contact portion are arranged on opposite sides of the opening.

[0075] Alternatively, the heater assembly may include an even number of heater elements, preferably two or four heater elements. In this embodiment, the contact portions are preferably located on the same side of the cartridge. In this arrangement, a more compact design of the electrical connection of the heater assembly to the power supply may be achieved.

[0076] In some embodiments, at least one heater element has a first face fixed to an electrically insulated substrate, and the first conductive contact portion and the second conductive contact portion are configured to be in contact with an external power supply on a second face that is opposite to the first face of the heater element.

[0077] The provision of the conductive contact portion forming part of the heater element allows for a reliable and simple connection of the heater assembly to the power supply.

[0078] When the heater assembly includes a plurality of heater elements, at least one of the plurality of heater elements may include a first material, and at least one of the other of the plurality of heater elements may include a second material different from the first material. This may be beneficial for electrical or mechanical reasons. For example, one or more of the heater elements may be formed of a material having a resistance that varies significantly with temperature, such as an iron-aluminum alloy. Thereby, the resistance of the heater element used to determine the temperature or temperature change can be measured. This can be used for controlling the heater temperature to keep the heater temperature within a desired temperature range in a smoking detection system.

[0079] The electric resistance of the heater assembly is preferably from 0.3 to 4 ohms. More preferably, the electric resistance of the heater assembly is from 0.5 to 3 ohms, and even more preferably about 1 ohm.

[0080] When at least one heater element of the heater assembly comprises an array of conductive filaments and the heater assembly further comprises a conductive contact portion for contact with at least one heater element, the electric resistance of the array of conductive filaments is preferably at least one order of magnitude greater than the electric resistance of the contact portion, and more preferably at least two orders of magnitude greater. Thereby, the heat generated by passing an electric current through at least one heater element is surely localized in a plurality of conductive filaments. When a cartridge is used in an aerosol generating system where the power source is a battery, it is generally advantageous for the heater assembly to have a low overall resistance. It is also desirable to minimize the parasitic losses between the electrical contacts and the filaments in order to minimize the parasitic power losses. A low-resistance and high-current system can deliver high power to the heater assembly. Thereby, the heater assembly can quickly heat the conductive filaments to a desired temperature.

[0081] The conductive contact portion may be directly fixed to the conductive filament. The contact portion may be positioned between the conductive filament and a substrate electrically insulated from the conductive filament. For example, the contact portion may be formed from a copper foil plated on an insulating substrate. The contact portion may be more easily coupled to the filament than the insulating substrate is coupled.

[0082] Alternatively, the conductive contact portion may be integral with the conductive filaments of the heater element. For example, the heater element may be formed by providing a plurality of filaments between two contact portions by etching or electroforming a conductive sheet.

[0083] At least one heater element of the heater assembly may comprise at least one filament made of a first material and at least one filament made of a second material different from the first material. This may be beneficial for electrical or mechanical reasons. For example, one or more of the filaments may be formed from a material having a resistance that varies significantly with temperature, such as an iron-aluminum alloy. Thereby, the resistance of the filament used to determine the temperature or temperature change can be measured. This can be used for controlling the heater temperature to keep the heater temperature within a desired temperature range within a smoking detection system.

[0084] The heater assembly is preferably substantially planar.

[0085] The term "substantially planar" heater assembly is used to refer to a heater assembly that is formed within a single plane and is not wound around or otherwise conformed to a curved shape or other non-planar shape. Thus, a substantially planar heater assembly extends substantially more in two dimensions along the surface than in a third dimension. In particular, the dimensions of the substantially planar heater assembly within the surface in two dimensions are at least five times larger than the third dimension perpendicular to the surface. A planar heater assembly can be easily handled during manufacturing and provides a robust structure.

[0086] At least one heater element may be formed by joining a plurality of conductive filaments together, for example, to form a mesh by soldering or welding. At least one heater element is preferably formed by one of both etching (e.g., wet etching) and electroforming. In either case, a mask or mandrel may be used to create a specific pattern of openings on the heater element. Advantageously, these processes are very accurate and can create heater elements with better controlled opening sizes. This may improve the reproducibility of the performance characteristics from heater to heater.

[0087] An aerosol-forming substrate is a substrate having the ability to release a volatile compound capable of forming an aerosol. The volatile compound may be released by heating the aerosol-forming substrate.

[0088] The aerosol-forming substrate may comprise a plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a tobacco-containing material containing a volatile tobacco flavor compound released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may comprise a non-tobacco-containing material. The aerosol-forming substrate may comprise a homogenized plant-derived material. The aerosol-forming substrate may comprise a homogenized tobacco material. The aerosol-forming substrate may comprise at least one aerosol former. The aerosol former is any suitable known compound or mixture of compounds that facilitates the formation of a dense and stable aerosol during use and is substantially resistant to thermal decomposition at the operating temperature of the system. Suitable aerosol formers are well known in the art and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, and glycerol), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic, dicarboxylic, or polycarboxylic acids (such as dimethyl dodecanedioate and dimethyl tetradecanedioate). Preferred aerosol formers are polyhydric alcohols or mixtures thereof (such as triethylene glycol, 1,3-butanediol, and glycerol (most preferred)). The aerosol-forming substrate may comprise other additives and components (such as flavorants).

[0089] According to a third aspect of the present invention, there is provided an aerosol generating system comprising an aerosol generating device and a cartridge according to any of the above-described embodiments, the cartridge being removably coupled to the device, and the device comprising a power source for a heater assembly.

[0090] As used herein, "removably coupled" of a cartridge to an apparatus means that the cartridge and the apparatus can be coupled and separated from each other without significant damage to either the apparatus or the cartridge.

[0091] The cartridge is replaceable after consumption. Since the cartridge holds the aerosol-forming substrate and the heater assembly, the heater assembly is also periodically replaced so that optimal vaporization conditions are maintained even after long-term use of the main unit.

[0092] The system may be an electrically operated smoking system. The system may be a handheld aerosol generating system. The aerosol generating system may be sized comparable to a conventional cigar or cigarette. The overall length of the smoking system may be approximately 30 millimeters to approximately 150 millimeters. The outer diameter of the smoking system may be an outer diameter of approximately 5 millimeters to approximately 30 millimeters.

[0093] The system may further comprise an electric circuit connected to the heater assembly and a power source, the electric circuit being configured to monitor the electrical resistance of one or more filaments of the heater assembly or at least one heater element of the heater assembly and to control the power supply from the power source to the heater assembly depending on the electrical resistance of the heater assembly or specifically of one or more filaments. By monitoring the temperature of the heater element, the system can prevent overheating or underheating of the heater assembly and ensure optimal vaporization conditions.

[0094] The electrical circuit may comprise a microprocessor, which may be a programmable microprocessor, a microcontroller, or an application-specific integrated circuit (ASIC) or other electronic circuit having the ability to provide control. The electrical circuit may further comprise additional electronic components. The electrical circuit may be configured to regulate the power supply to the heater. The power may be continuously supplied to the heater assembly after startup of the system, or may be supplied intermittently, such as for each smoking event. The power may be supplied to the heater assembly in the form of current pulses.

[0095] The aerosol generating device includes a power source for the heater assembly of the cartridge. The power source may be a battery within a device, such as a lithium iron phosphate battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity to store sufficient energy for one or more smoking experiences. For example, the power source may have a capacity sufficient to continuously generate aerosol for about 6 minutes, or a multiple of 6 minutes, corresponding to the typical time taken to smoke one conventional cigarette. In another embodiment, the power source may have a capacity sufficient to enable a predetermined number of smoking events, or discontinuous activation of the heater.

[0096] The storage portion may be positioned above the first side of the heater assembly, and the airflow channel may be positioned above the side of the heater assembly opposite the storage portion such that the airflow passing through the heater assembly mixes with the aerosol-forming substrate that has been vaporized.

[0097] According to a fourth aspect of the present invention, there is provided a method of manufacturing a cartridge for use in an aerosol generating system, the method comprising providing a storage portion comprising a housing having an opening, filling the storage portion with an aerosol forming substrate, and providing a heater assembly comprising at least one heater element extending across the opening of the housing, wherein at least one heater element of the heater assembly has a plurality of openings such that fluid can pass through the at least one heater element, and the plurality of openings have different sizes.

[0098] According to a fifth aspect of the present invention, there is provided a method of manufacturing a cartridge for use in an aerosol generating system, the method comprising providing a storage portion comprising a housing having an opening, filling the storage portion with an aerosol forming substrate, and providing a heater assembly comprising at least one heater element extending across the opening of the housing, wherein at least one heater element of the heater assembly comprises an array of conductive filaments extending along the length of the at least one heater element, and a plurality of transverse conductive filaments extending in a direction transverse to the array of conductive filaments and thereby connecting adjacent filaments in the array of conductive filaments, the gaps between the conductive filaments and the gaps between the transverse conductive filaments defining a plurality of openings such that fluid can pass through the at least one heater element, and at least some, preferably substantially all, of the plurality of transverse conductive filaments extend only over a part of the width of the at least one heater element and are offset along the length of the at least one heater element.

[0099] The features described in relation to one or more aspects may equally apply to other aspects of the present invention. In particular, the features described in relation to the cartridge of the first aspect may equally apply to the cartridge of the second aspect, and vice versa. And the features described in relation to either the cartridge of the first aspect or the second aspect may equally apply to the methods of manufacture of the fourth and fifth aspects.

[0100] Here, embodiments of the present invention will be described by way of illustration only with reference to the following accompanying drawings.

Brief Description of the Drawings

[0101]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0102] FIGS. 1A to 1D are schematic diagrams of an aerosol generating system including a cartridge according to an embodiment of the present invention. FIG. 1A is a schematic diagram of an aerosol generating device 10, i.e., the main unit, and a separate cartridge 20, which together form an aerosol generating system. In this example, the aerosol generating system is an electrically operated smoking system.

[0103] The cartridge 20 includes an aerosol-forming substrate and is configured to be received within the recess 18 in the device. The cartridge 20 should be replaceable by the user when the aerosol-forming substrate provided within the cartridge is depleted. FIG. 1A shows the cartridge 20 immediately prior to insertion into the device, and arrow 1 in FIG. 1A indicates the direction of insertion of the cartridge.

[0104] The aerosol-generating device 10 is portable and has a size comparable to that of a conventional cigar or cigarette. The device 10 includes a body 11 and a mouthpiece portion 12. The body 11 includes a battery 14 (such as a lithium iron phosphate battery), control electronics 16, and a recess 18. The mouthpiece portion 12 is connected to the body 11 by a hinged connection 21 and is movable between an open position shown in FIGS. 1A - 1C and a closed position shown in FIG. 1D. The mouthpiece portion 12 is placed in the open position to allow insertion and removal of the cartridge 20 and is placed in the closed position when the system is used for aerosol generation, as described below. The mouthpiece portion includes a plurality of air inlets 13 and an air outlet 15. In use, the user sucks or inhales at the outlet, drawing air from the air inlets 13 through the mouthpiece portion to the outlet 15 and then into the user's mouth or lungs. An internal baffle 17 is provided to force the flow of air passing through the cartridge through the mouthpiece portion, as described below.

[0105] The recess 18 has a circular cross-section and is sized to receive the housing 24 of the cartridge 20. An electrical connector 19 is provided on the side of the recess 18 to provide an electrical connection between the control electronics 16 and the battery 14 and corresponding electrical contacts of the cartridge 20.

[0106] FIG. 1B shows the system of FIG. 1A with the cartridge inserted into the recess 18 and the cover 26 removed. In this position, the electrical connector is positioned relative to the electrical contacts on the cartridge, as described below.

[0107] Figure 1C shows the system of Figure 1B with the cover 26 completely removed and the mouthpiece portion 12 moving to the closed position.

[0108] Figure 1D shows the system of Figure 1C with the mouthpiece portion 12 in the closed position. The mouthpiece portion 12 is held in the closed position by a fastening mechanism (not shown). It will be apparent to those skilled in the art that other suitable mechanisms (such as snap-on mounting or magnetic closures) may be used to hold the mouthpiece in the closed position.

[0109] The mouthpiece portion 12 in the closed position keeps the cartridge in electrical contact with the electrical connector 19 so that a good electrical connection is maintained during use regardless of the orientation of the system. The mouthpiece portion 12 may include an annular elastic element that engages the surface of the cartridge and is compressed between the rigid mouthpiece housing element and the cartridge when the mouthpiece portion 12 is in the closed position. This ensures that a good electrical connection is maintained regardless of manufacturing tolerances.

[0110] Of course, other mechanisms for maintaining a good electrical connection between the cartridge and the device may be employed alternatively or additionally. For example, the housing 24 of the cartridge 20 may be provided with a thread or groove (not shown) that engages a corresponding groove or thread (not shown) formed in the wall of the recess 18. The threaded engagement between the cartridge and the device can be used not only for correct rotational alignment but also for holding the cartridge in the recess and ensuring a good electrical connection. The threaded connection may extend for less than half a rotation or several rotations of the cartridge. Alternatively or additionally, the electrical connector 19 may be biased to contact the contacts on the cartridge.

[0111] Figure 2 is an exploded view of a cartridge 20 suitable for use in an aerosol generation system, for example, an aerosol generation system of the type shown in Figure 1. The cartridge 20 has a generally circular cylindrical housing 24 sized and shaped to be received within a corresponding recess of the aerosol generation system, such as recess 18 of the system of Figure 1, or otherwise attached in a suitable manner using other elements. The housing 24 contains an aerosol forming substrate. In this embodiment, the aerosol forming substrate is a liquid, and the housing 24 further includes a capillary material 22 immersed in the liquid aerosol forming substrate. In this example, the aerosol forming substrate comprises 39 weight percent glycerin, 39 weight percent propylene glycol, 20 weight percent water and flavorant, and 2 weight percent nicotine. The capillary material is a material that actively transports liquid from one end to the other and may be made of any suitable material. In this example, the capillary material is formed from polyester. In other embodiments, the aerosol forming substrate may be a solid.

[0112] The housing 24 has an open end to which a heater assembly 30 is secured. The heater assembly 30 comprises a substrate 34 having an opening 35 formed therein, a pair of electrical contacts 32 secured to the substrate and separated from each other by a gap 33, and a heater element 36 formed from a mesh of conductive heater filaments that extends across the opening 35 and is secured to the electrical contacts 32 on the opposite side of the opening 35.

[0113] The heater assembly 30 is covered by a removable cover 26. The cover 26 comprises a liquid-impermeable plastic sheet that is adhered to the heater assembly but can be easily peeled off. Tabs are provided on the sides of the cover so that the user can grasp the cover 26 when peeling it off. Although adhesion is described here as a way to secure the impermeable plastic sheet to the heater assembly 30, it will be apparent to those skilled in the art that other methods, including heat sealing or ultrasonic welding, may also be used as long as the cover 26 can be easily removed by the consumer.

[0114] It will be understood that other cartridge designs are possible. For example, the capillary material used with the cartridge may comprise two or more separate capillary materials, or the cartridge may comprise a tank for holding a reservoir of free liquid.

[0115] The heater filament of the heater element 36 is exposed through the opening 35 of the substrate 34 so that the vaporized aerosol-forming substrate can pass through the heater assembly and exit into the air stream.

[0116] In use, the cartridge 20 is placed within an aerosol-generating system and the heater assembly 30 is contacted with a power supply provided within the aerosol-generating system. An electronic circuit supplies power to the heater element 36 and is provided to vaporize the aerosol-forming substrate.

[0117] Figure 3 depicts a first embodiment of the heater assembly 30 of the present invention, where three substantially parallel heater elements 36a, 36b, 36c are electrically connected in series. The heater assembly 30 comprises an electrically insulated substrate 34 in which a square opening 35 is formed. The size of the opening is 5 millimeters × 5 millimeters in this embodiment, although of course other shaped and sized openings may be used depending on the requirements for the particular application of the heater. A first conductive contact portion 32a and a second conductive contact portion 32b are provided on opposite sides of the opening 35 so as to be able to contact an external power source. Of the three serially connected heater elements 36a, 36b, and 36c, the first contact portion 32a contacts the first heater element 36a, and the second contact portion 32b contacts the third heater element 36c. Two additional conductive contact portions 32c and 32d are provided adjacent to the first contact portion 32a and the second contact portion 32b so as to enable the series connection of the heater elements 36a, 36b, and 36c. The first heater element 36a is connected between the first contact portion 32a and the additional contact portion 32c. The second heater element 36b is connected between the additional contact portion 32c and the additional contact portion 32d. The third heater element 36c is connected between the additional contact portion 32d and the second contact portion 32b. In this embodiment, the heater assembly 30 comprises an odd number of heater elements 36, namely three heater elements, and the first contact portion 32a and the second contact portion 32b are located on opposite sides of the opening 35 of the substrate 34. The heater elements 36a and 36c are spaced from the side edges 35a and 35c of the opening so that there is no direct physical contact between these heater elements 36a and 36c and the insulating substrate 34. Without wishing to be bound by any particular theory, it is believed that this arrangement can reduce heat transfer to the insulating substrate 34 and allow for effective vaporization of the aerosol generating substrate.

[0118] In this embodiment, the heater elements 36a, 36b, and 36c each comprise a strip of conductive material formed from an array of conductive filaments, as discussed below with respect to FIGS. 4 and 5. The heater elements 36a, 36b, 36c each comprise a plurality of openings (not shown) through which fluid may pass through the heater assembly 30. As shown in FIG. 4, the size of the openings may be substantially constant across the area of the opening 35. Alternatively, the size of the openings may vary. For example, in the central portion 35e of the opening 35, the size of the openings may be larger than the size of the openings outside the central portion 35e, as discussed with respect to FIG. 5. In some embodiments, the heater element 36b defines a plurality of openings having a different size than the plurality of openings defined by the heater elements 36a and 36c. For example, the heater element 36b may define a plurality of openings having a size larger than the plurality of openings defined by the heater elements 36a and 36c.

[0119] In FIG. 4, an enlarged partial view of one of the heater elements of FIG. 3 is shown. The heater element 36 comprises a conductive filament 37 extending along the length of the heater element 36, and an array of a plurality of transverse conductive filaments 38 extending substantially at right angles to the filament 37. The heater element 36 may be made of any suitable material, for example 316L stainless steel. The filaments 37 are connected together by the transverse filaments 38 to provide increased rigidity and strength to the heater element 36. The conductive filaments 37 are substantially parallel and are spaced apart via gaps such that a gap is defined between adjacent filaments 37. The transverse conductive filaments 38 are also substantially parallel and are spaced apart via gaps such that a gap is defined between adjacent transverse filaments 38. The gaps between the conductive filament 37 and the array of the plurality of transverse conductive filaments 38 define a plurality of openings 39 through which fluid may pass through the heater element 36. In this embodiment, the gap between adjacent transverse filaments 38 in the axial direction is larger than the gap between adjacent filaments 37, such that each of the plurality of openings 39 is elongated in the length direction of the heater element 36. In the arrangement shown in FIG. 4, each of the transverse filaments 38 extends across only a single gap between two adjacent filaments 37, and the continuous transverse filaments 38 across the width of the heater element 36 are offset along the length of the heater element, i.e., offset in the length direction of the heater element 36. This arrangement causes the junctions between the filaments 37 and the transverse filaments 38 to each define three electrical paths, one of which is in the general direction of the current flowing through the heater element 36 as illustrated by the arrow 40, one of which is transverse to the general direction of the current flow, and the other of which is in the direction opposite to the general direction of the current flow. This is in contrast to a conventional cross-intersecting mesh. In a conventional cross-intersecting mesh, the junctions between the filaments each define four electrical paths, one of which is in the general direction of the current flowing through the heater element, two of which are transverse to the general direction of the current flow, and the remaining one is in the direction opposite to the general direction of the current flow.

[0120] While not wishing to be bound by any particular theory, by reducing the number of transverse conductive elements and thus the number of electrical paths, the heater element of the present invention can better maintain the current direction across the heater element, resulting in a reduction in the variation of the temperature profile across the heater element area, leading to fewer high temperature points, and this is thought to potentially reduce performance variation.

[0121] Furthermore, by shifting the transverse filaments 38 along the length of the heater element, the unsupported length of each filament 37 is reduced. Consequently, the length of the openings can be increased without a detrimental effect on the strength or rigidity of the heater element. This may enable the fluid flow characteristics of the heater element and the aerosol delivery characteristics of the cartridge to be varied as desired without a detrimental effect on the rigidity or structural stability of the heater element.

[0122] In the partial view of the heater element shown in FIG. 4, the sizes of the plurality of openings 39 are substantially the same over the width and length of the portion of the heater element 36 shown, as indicated by the width dimension 41 and the length dimension 42. In this embodiment, the openings 39 are rectangular and each have a width of 58 micrometers and a length of 500 micrometers, although of course openings of other shapes and sizes can be used as required for a particular application of the heater. The conductive filaments 37, 38 forming the heater element 36 each have a width and a thickness of 20 micrometers, although of course filaments of other sizes can be used as required for a particular application of the heater. The portion of the heater element 36 shown in FIG. 4 has a length corresponding to three openings and a width corresponding to six openings, although the entire heater element 36 may be longer and wider. In one embodiment, the heater element has a length corresponding to twelve openings and a width corresponding to twenty-one openings. Such a heater element has an overall width of 1.658 millimeters (22×20 micrometers + 21×58 micrometers) and an overall length of 6.26 millimeters (13×20 micrometers + 12×500 micrometers).

[0123] In FIG. 5, an enlarged partial view of an alternative embodiment of the heater element is shown. The portion of the heater element of FIG. 5 is similar to the portion of the heater element shown in FIG. 4, except that the sizes of the plurality of openings 39' defined by the array of conductive filaments 37' and the plurality of transverse conductive filaments 38' vary over the length of the portion of the heater element 36' shown. Specifically, the widths of the openings are substantially the same as indicated by the width dimension 41', but the gaps between the transverse filaments are larger, such as length 43', in the central portion of the heater element 36', and thus the overall size of the openings 39' in the central portion of the heater element 36' is larger than the openings 39' of length 42' outside the central portion. In this embodiment, the openings 39' in the central portion each have a width of 58 micrometers and a length of 600 micrometers.

[0124] In FIG. 6, a second embodiment of the heater assembly 30 of the present invention is illustrated, in which three substantially parallel heater elements 36a, 36b, 36c are electrically connected in series. The heater assembly 30 includes an electrically insulated substrate 34 in which a square opening 35 is formed. The size of the opening is 5 millimeters × 5 millimeters in this embodiment, although of course other shaped and sized openings may be used depending on the requirements for the particular application of the heater. The first and second conductive contact portions 32a, 32b are provided on opposite sides of the opening 35 and extend substantially parallel to the side edges 35a, 35b of the opening 35. Two additional conductive contact portions 32c, 32d are provided adjacent to portions of the side edges 35c, 35d on the opposite side of the opening 35. The first heater element is connected between the first contact portion 32a and the additional contact portion 32c. The second heater element 36b is connected between the additional contact portion 32c and the additional contact portion 32d. The third heater element 36c is connected between the additional contact portion 32c and the second contact portion 32b. In this embodiment, the heater assembly 30 includes an odd number of heater elements 36, namely three heater elements, and the first contact portion 32a and the second contact portion 32b are located on opposite sides of the opening 35 in the substrate 34. The heater elements 36a and 36c are spaced from the side edges 35a, 35b of the opening so that there is no direct physical contact between these heater elements 36a, 36c and the insulating substrate 34. Without wishing to be bound by any particular theory, it is believed that this arrangement can reduce heat transfer to the insulating substrate 34 and allow for effective vaporization of the aerosol generating substrate.

[0125] FIG. 7 shows a further embodiment of the heater assembly 20 of the present invention, in which four heater elements 36a, 36b, 36c, 36d are electrically connected in series. The heater assembly 30 comprises an electrically insulated substrate 34 in which a square opening 35 is formed. The size of the opening is 5 millimeters × 5 millimeters. The first conductive contact portion 32a and the second conductive contact portion 32b are provided adjacent to the upper and lower portions, respectively, of the same side edge 35b of the opening 35. Three additional conductive contact portions 32c, 32d, 32e are provided, where two additional contact portions 32d, 32e are provided adjacent to portions of the opposite side edge 35a, and one additional contact portion 32c is provided parallel to the side edge 35b between the first contact portion 32a and the second contact portion 32b. The four heater elements 36a, 36b, 36c, 36d are connected in series between these five contact portions 32a, 32c, 32d, 32e, 32b as shown in FIG. 7. Again, none of the long side edges of the heater elements are in direct physical contact with any of the side edges of the opening so that heat transfer to the insulating substrate is reduced here.

[0126] In this embodiment, the heater assembly 30 comprises an even number of heater elements 36, namely four heater elements 36a, 36b, 36c, 36d, and the first contact portion 32a and the second contact portion 32b are located on the same side of the opening 35 of the substrate 34.

[0127] In arrangements such as those shown in FIGS. 3, 6, and 7, the arrangement of the heater elements may be such that the gaps between adjacent heater elements are substantially the same. For example, the heater elements may be regularly spaced across the width of the opening 35. In other arrangements, for example, different spacings may be used between the heater elements in order to obtain a desired heating profile. Other shapes of openings or heater elements may be used.

[0128] In the embodiments described above with respect to FIGS. 1-7, the heater assembly comprises one or more heater elements having a plurality of heater filaments and transverse heater filaments formed from a conductive sheet of 316L stainless steel foil etched or electroformed to define the filaments. The filaments have a thickness and width of about 20 micrometers. The heater elements are connected to electrical contacts 32 separated from each other by a gap of about 100 micrometers and are formed of copper foil having a thickness of about 30 micrometers. The electrical contacts 32 are provided on a polyimide substrate 34 having a thickness of about 120 micrometers. The contact portions are preferably plated with, for example, gold, tin, or silver. The filaments forming the heater elements are spaced apart via gaps so as to define a gap between adjacent filaments, and the transverse filaments forming the heater elements are also spaced apart via gaps so as to define a gap between adjacent transverse filaments. The gaps between adjacent filaments and transverse filaments define a plurality of openings through which fluid may pass through the heater assembly. In this example, the plurality of openings have a width of about 58 micrometers and a length, for example, of 500 micrometers to 600 micrometers, which varies over the length, width, or length and width of the heater element, although larger or smaller openings may be used. By using heater elements having these approximate dimensions, in some embodiments a meniscus of the aerosol-forming substrate is formed within the openings and the aerosol-forming substrate can be drawn by capillary action for the heater elements of the heater assembly. The opening area of the heater element, i.e., the ratio of the area of the plurality of openings to the total area of the heater element, is advantageously 25 percent to 56 percent. The total resistance of the heater assembly is about 1 ohm. The filaments of the heater elements provide most of this resistance such that most of the heat is generated by the filaments. In certain embodiments, the filaments of the heater elements have an electrical resistance that is 100 times or more higher than that of the electrical contacts 32.

[0129] The substrate 34 is electrically insulated and, in this embodiment, is formed from a polyimide sheet having a thickness of about 120 micrometers. The substrate is circular and has a diameter of 8 millimeters. The heater element is rectangular and, in some embodiments, has side lengths of 5 millimeters and 1.6 millimeters. These dimensions enable the fabrication of a complete system that is similar in size and shape to a conventional cigarette or cigar. Another example of dimensions that have been found to be effective is a circular substrate with a diameter of 5 millimeters and a rectangular heater element of 1 millimeter × 4 millimeters.

[0130] The heater element may be directly bonded to the substrate 34, and then the contact 32 may be at least partially bonded over the heater element. Having the contact as the outermost layer may be beneficial in providing a reliable electrical contact with the power source. A plurality of filaments may be formed integrally with the conductive contact portion.

[0131] In the cartridge shown in FIG. 2, the contact 32 and the heater element 36 are located between the substrate layer 34 and the housing 24. However, it is also possible to mount the heater assembly inversely in the cartridge housing such that the polyimide substrate 34 is directly adjacent to the housing 24.

[0132] The described embodiments have a cartridge with a housing having a substantially circular cross-section, but it is of course also possible to form a housing for a cartridge having other shapes, such as a rectangular cross-section or a triangular cross-section. These housing shapes ensure a desired orientation within a correspondingly shaped recess and ensure an electrical connection between the device and the cartridge.

[0133] The capillary material 22 is advantageously directed within the housing 24 to convey liquid to the heater assembly 30. When the cartridge is assembled, the heater filaments 37, 38 may contact the capillary material 22, so that the aerosol-forming substrate can be conveyed directly to the heater. In an embodiment of the invention, the aerosol-forming substrate contacts most of the surface of each filament 37, 38 so that most of the heat generated by the heater assembly directly enters into the aerosol-forming substrate. In contrast, in conventional wick and coil heater assemblies, only a very small portion of the heater wire contacts the aerosol-forming substrate. The capillary material 27 may extend into the opening.

[0134] In use, the heater assembly preferably operates by resistive heating, but may operate using other suitable heating processes such as inductive heating. When the heater assembly operates by resistive heating, an electric current passes through the filaments 37, 38 of the heater element 36 under the control of the control electronic circuit 16 to heat the filaments within a desired temperature range. The filaments have a significantly higher electrical resistance than the contact portion 32 so that a high temperature is localized at the filaments. The system may be configured to generate heat by supplying an electric current to the heater assembly in response to the user's smoking, or may be configured to continuously generate heat while the device is in the "on" state. Different materials for the filaments may be appropriate for different systems. For example, in a continuous heating system, a graphite filament is appropriate because it has a relatively low specific heat capacity and is compatible with low current heating. In a system that operates by smoking in which heat is generated by short bursts using high current pulses, a stainless steel filament having a high specific heat capacity may be more appropriate.

[0135] In a system actuated by smoking, the device may include a smoking sensor configured to detect when the user inhales air through the mouthpiece portion. The smoking sensor (not shown) is connected to a control electronic circuit 16, which is configured to supply current to the heater assembly 30 only when it is determined that the user is smoking the device. Any suitable airflow sensor, such as a microphone, may be used as the smoking sensor.

[0136] In a possible embodiment, a change in the specific resistance of one or more of the filaments 37, 38 or of the heater element as a whole may be used to detect a change in the temperature of the heater element. This can be used to regulate the power supplied to the heater element so as to be reliably maintained within the desired temperature range. A rapid change in temperature may also be used as a means of detecting a change in the airflow passing through the heater element, which results from the user smoking the system. One or more of the filaments may be dedicated temperature sensors and may be formed from a material having a temperature coefficient of resistance suitable for that purpose, such as an iron-aluminum alloy, Ni-Cr, platinum, tungsten, or alloy wire.

[0137] The airflow passing through the mouthpiece portion when the system is in use is shown in FIG. 1d. The mouthpiece portion includes an internal baffle 17 that is integrally formed with the outer wall of the mouthpiece portion and through which air flows over the heater assembly 30 located on a cartridge in which the aerosol-forming substrate is vaporized as the air is drawn from the inlet 13 to the outlet 15. As the air passes through the heater assembly, the vaporized substrate mixes into the airflow and is cooled to form an aerosol before exiting through the outlet 15. Thus, in use, the aerosol-forming substrate passes through the heater assembly by passing through the gap between the filaments 36, 37, 38 when it is vaporized.

[0138] One skilled in the art could devise other cartridge designs incorporating the heater assembly according to the present disclosure. For example, the cartridge may include a mouthpiece portion, may include a plurality of heater assemblies, and may have any desired shape. Moreover, the heater assembly according to the present disclosure may be used in other types of systems different from those already described (such as humidifiers, air fresheners, and other aerosol generation systems).

[0139] The above exemplary embodiments are illustrative but not limiting. In light of the exemplary embodiments discussed above, other embodiments consistent with the above exemplary embodiments will now be apparent to those skilled in the art.

[0140] 1. A cartridge for use in an aerosol generation system, comprising: A housing for holding an aerosol-forming substrate, the housing having a storage portion with an opening; A heater assembly fixed to the housing and extending across the opening of the housing, the heater assembly comprising at least one heater element; The cartridge wherein the at least one heater element of the heater assembly defines a plurality of openings such that fluid can pass through the at least one heater element, and the plurality of openings have different sizes. 2. The cartridge according to claim 1, wherein the size of the openings in a first region of the opening is larger than the size of the openings in a second region of the opening. 3. The cartridge according to claim 1 or 2, wherein the size of the openings increases towards a central portion of the opening. 3. The cartridge according to any one of claims 1 to 2, wherein the at least one heater element comprises an array of conductive filaments extending along the length of the at least one heater element, and the plurality of openings are defined by gaps between the conductive filaments. 4. The at least one heater element further comprises a plurality of transverse filaments extending in a transverse direction with respect to the array of conductive filaments, thereby connecting adjacent filaments in the array of conductive filaments, and the plurality of openings are defined by the gaps between the conductive filaments and the gaps between the transverse filaments. The cartridge according to 3. 5. The cartridge according to 4, wherein the gap between the transverse filaments varies over at least the length, width, or length and width of the heater element so that the plurality of openings have different lengths. 6. The cartridge according to 4 or 5, wherein at least a portion, preferably substantially all, of the plurality of transverse filaments extends only over a part of the width of the at least one heater element and is offset along the length of the at least one heater element. 7. A cartridge for use in an aerosol generating system, a housing for holding an aerosol-forming substrate, the housing having an opening, a storage portion, a heater assembly fixed to the housing and extending across the opening of the housing, the heater assembly comprising at least one heater element, the at least one heater element of the heater assembly comprising an array of conductive filaments extending along the length of the at least one heater element and a plurality of transverse filaments extending in a transverse direction with respect to the array of conductive filaments, thereby connecting adjacent filaments in the array of conductive filaments, the gaps between the conductive filaments and the gaps between the transverse filaments define a plurality of openings so that fluid can pass through the at least one heater element. A cartridge in which at least a part, preferably substantially all, of the plurality of transverse filaments extends only over a part of the width of the at least one heater element and is offset along the length of the at least one heater element. 8. The cartridge according to any one of 4 to 7, wherein the transverse filament is conductive. 9. The cartridge according to any one of 1 to 8, wherein the heater assembly is substantially planar. 10. An aerosol generating system, an aerosol generating device, and a cartridge according to any one of 1 to 9, wherein the cartridge is removably coupled to the aerosol generating device, and the aerosol generating device includes a power source for the heater assembly. 11. The aerosol generating system according to 10, wherein the aerosol generating system is an electrically operated smoking system. 12. A method of manufacturing a cartridge for use in an aerosol generating system, the method comprising: providing a storage portion having a housing with an opening; filling the storage portion with an aerosol forming substrate; and providing a heater assembly having at least one heater element extending across the opening of the housing, wherein the at least one heater element of the heater assembly has a plurality of openings such that fluid can pass through the at least one heater element, and the plurality of openings have different sizes. 13. A method of manufacturing a cartridge for use in an aerosol generating system, the method comprising: providing a storage portion having a housing with an opening; filling the storage portion with an aerosol forming substrate; providing a heater assembly comprising at least one heater element extending across the opening of the housing; the at least one heater element of the heater assembly comprising an array of conductive filaments extending along the length of the at least one heater element and a plurality of transverse conductive filaments extending in a direction transverse to the array of conductive filaments, thereby connecting adjacent filaments in the array of conductive filaments; gaps between the conductive filaments and gaps between the transverse conductive filaments defining a plurality of openings allowing fluid to pass through the at least one heater element; a method wherein at least a part, preferably substantially all, of the plurality of transverse conductive filaments extends only over a part of the width of the at least one heater element and is offset along the length of the at least one heater element. 14. The method according to 12 or 13, wherein the at least one heater element is formed by etching.

Claims

1. A cartridge for an aerosol generation system, the cartridge comprising: a liquid storage portion including a housing containing a liquid aerosol-forming substrate; a heater assembly including an electrical heating element configured to heat the liquid aerosol-forming substrate to form an aerosol; a capillary material physically contacting the electrical heating element and including a ceramic or ceramic-based material, the capillary material being configured to convey the liquid aerosol-forming substrate to the electrical heating element by capillary action; the electrical heating element being supported by an electrically insulating substrate having an opening; the heater assembly being disposed on the opposite side of the opening and further including first and second conductive contact portions configured to contact a battery configured to supply power to the heater assembly; the electrical heating element having a first surface fixed to the electrically insulating substrate and a second surface opposite the first surface, the second surface facing the capillary material; the heater assembly being fixed to the housing of the liquid storage portion. A cartridge.

2. The cartridge according to claim 1, wherein both the capillary material and the electrically insulating substrate are disposed in contact with the electrical heating element.

3. The cartridge according to claim 1, wherein the opening of the electrically insulating substrate has a circular shape, a square shape, or a rectangular shape.

4. The cartridge according to claim 1, wherein the heater assembly is covered by a removable cover.

5. The cartridge according to claim 1, wherein the electrical heating element includes a filament disposed in a curved manner between the two conductive contact portions respectively connected to the ends of the filament.

6. The cartridge according to claim 1, wherein the capillary material includes first and second capillary materials.

7. The first capillary material physically contacts the heater assembly; The second capillary material physically contacts the first capillary material and is spaced apart from the heater assembly by the first capillary material. The cartridge according to claim 6.

8. The cartridge according to claim 1, wherein the electrical heating element is in fluid communication with the liquid aerosol-forming substrate.

9. The cartridge according to claim 5, wherein the filament comprises a material selected from the group consisting of semiconductors, doped ceramics, undoped ceramics, conductive ceramics, carbon, graphite, metals, metal alloys, composites of ceramic materials and metal materials, and combinations thereof.

10. An aerosol generating system comprising: an aerosol generating device including a power source; and a cartridge removably coupled to the aerosol generating device, the cartridge comprising: a liquid storage portion including a housing containing a liquid aerosol forming substrate; a heater assembly including an electrical heating element configured to heat the liquid aerosol forming substrate to form an aerosol; a capillary material physically contacting the electrical heating element and including a ceramic or ceramic-based material, the capillary material being configured to convey the liquid aerosol forming substrate to the electrical heating element by capillary action; the electrical heating element being supported by an electrically insulating substrate having an opening; the heater assembly being disposed on the opposite side of the opening and further including first and second conductive contact portions configured to contact a battery; the electrical heating element having a first surface fixed to the electrically insulating substrate and a second surface opposite the first surface, the second surface facing the capillary material; the heater assembly being fixed to the housing of the liquid storage portion; the aerosol generating system, wherein the power source of the aerosol generating device is the battery and is configured to supply power to the heater assembly.

11. The aerosol generating system according to claim 10, wherein both the capillary material and the electrically insulating substrate are physically in contact with the electrical heating element.

12. The aerosol generating system according to claim 10, wherein the aerosol generating device further includes a main body and a mouthpiece portion, the mouthpiece portion including an internal baffle configured to force air flowing through the mouthpiece portion to pass through the cartridge.

13. The aerosol generating system according to claim 12, wherein the internal baffle is further configured to direct air to flow over the heater assembly.

14. The aerosol generation system according to claim 10, wherein the heater assembly is covered by a removable cover.

15. The aerosol generation system according to claim 10, wherein the electric heating element includes the filament arranged in a curved manner between the two conductive contact portions respectively connected to the ends of the filament.

16. The aerosol generation system according to claim 15, wherein the filament is substantially flat and curved along one or more directions thereof.

17. The aerosol generation system according to claim 10, wherein the aerosol generator further includes an electric circuit mechanism connected to the heater assembly and to the power source.

18. The aerosol generation system according to claim 17, wherein the electric circuit mechanism is configured to monitor the electrical resistance of the electric heating element and control the supply of power from the power source to the heater assembly.

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