Electrically heated smoking system with improved heating element

Abstract

An electrically heated smoking system for receiving an aerosol-forming substrate is provided. [Solution] The system includes at least one heater for heating an aerosol-forming substrate to form an aerosol, and a power supply for supplying power to the at least one heater. The at least one heater includes one or more conductive tracks (103, 203, 303, 403, 503) on an electrically insulating substrate (101, 201, 301, 401, 501). In one configuration, one or more conductive tracks (103, 203, 303, 403, 503) have a resistance temperature coefficient characteristic so that one or more conductive tracks can act as a resistance heater and temperature sensor. In another configuration, the electric heating smoking system further includes a thermal insulating material (507) for insulating the at least one heater from the outside of the electric heating smoking system.

Description

Technical Field

[0001] The present invention relates to an electrically heated smoking system comprising a heater for heating an aerosol-forming substrate.

Background Art

[0002] US-A-5 353 813 discloses a bladed tubular array for use as an external heating element in an electric smoking article. The heating element includes several carbon blades disposed around a reinforcing tube of spiral-wound paper. One electrical connection is formed at the free end of the blade, while a common ring of carbon connects to the other end of the carbon blade to form a common electrical connection. When power is supplied to the blades, they heat to provide a heating zone having a temperature in the range of 300 °C to about 900 °C.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor has recognized that it is advantageous to provide an electrically heated smoking system that is easier to manufacture and has fewer components in its configuration.

Means for Solving the Problems

[0005] A first aspect of the present invention provides an electrically heated smoking system for receiving an aerosol-forming substrate, the system comprising at least one heater for heating the substrate to form an aerosol, and a power supply for supplying power to the at least one heater, the at least one heater comprising one or more conductive tracks on an electrically insulating substrate, the one or more conductive tracks having a temperature coefficient of resistance such that the one or more conductive tracks can act as both a resistive heater and a temperature sensor.

[0006] A first aspect of the present invention also provides a heater for use in an electrically heated smoking system, the heater comprising one or more conductive tracks on an electrically insulating substrate.

[0007] A first aspect of the present invention also provides the use of a heater in an electrically heated smoking system, the heater comprising one or more conductive tracks on an electrically insulating substrate, the one or more conductive tracks having a resistance temperature coefficient characteristic such that the one or more conductive tracks can function as both a resistance heater and a temperature sensor.

[0008] By using a heater that incorporates conductive tracks on an electrically insulating substrate, which can function as both a heater and a temperature sensor, the number and size of components required for an electrically heated smoking system can be reduced. This reduces the overall size of the electrically heated smoking system. Furthermore, the electrically insulating substrate can be made very thin, allowing for further size reduction. Moreover, some or all of the necessary electronics, wiring, and connections can be incorporated onto the same electrically insulating substrate as the heater. Furthermore, the heater can be manufactured more directly and cost-effectively than some conventional heaters that require each heating element to be formed individually. The heater allows for great design flexibility, namely, the conductive tracks can be positioned on the electrically insulating substrate to provide the desired and preferred heat distribution.

[0009] Preferably, the electric heating smoking system further includes electronic circuits arranged to control the supply of power from a power source to at least one heater.

[0010] Preferably, the power supply provides power to at least one heater based on the temperature sensed by one or more conductive tracks and a desired temperature. That is, feedback is provided that enables the power supply to maintain the temperature of the heater and the aerosol-forming substrate at a specific desired temperature. This is achieved without the need for separate temperature sensors. Preferably, the electric heating smoking system includes electronic circuitry arranged as such for this purpose. Preferably, the desired temperature is the temperature at which the heater heats the aerosol-forming substrate but does not burn it.

[0011] Preferably, the electric heating smoking system further includes a thermal insulating material for insulating at least one heater. The thermal insulating material can insulate the material from the outside of the electric heating smoking system. Preferably, the heater includes a portion of an electric insulating substrate having a thermal insulating and / or reflective structure thereon.

[0012] A second aspect of the present invention provides an electrically heated smoking system for receiving an aerosol-forming substrate, the system comprising at least one heater having one or more conductive tracks on an electrically insulating substrate for heating the substrate to form an aerosol, a power supply for supplying power to the at least one heater, and a thermal insulating material for insulating the at least one heater.

[0013] A second aspect of the present invention also provides a thermal insulating material for use in an electrically heated smoking system having a heater comprising one or more conductive tracks on an electrically insulating substrate.

[0014] A second aspect of the present invention also provides the use of a thermal insulating material in an electrically heated smoking system having a heater comprising one or more conductive tracks on an electrically insulating substrate.

[0015] The thermal insulating material reduces heat loss from the heater and protects users of the electric smoking system from burns. Preferably, the thermal insulating material is positioned around the aerosol-forming substrate to provide maximum thermal insulation. The thermal insulating material must be a material that will not degrade at the high temperatures reached in the electric smoking system. Not all thermal insulating materials are suitable. Preferably, the thermal insulating material includes a metal or another non-combustible material. In one example, the metal is gold. In another example, the metal is silver. Metals are advantageous because they can reflect heat into the electric smoking system.

[0016] Preferably, the thermal insulating material includes a plurality of air cavities, which are arranged in a regular pattern. In one preferred embodiment, the air cavities are hexagonal and arranged in a honeycomb structure. The thermal insulating material can be provided on an electrically insulating substrate in addition to the conductive track, thereby enabling the manufacture of the conductive track and the thermal insulating material as a single element. In some manufacturing methods, the conductive track and the thermal insulating material can be manufactured as part of the same process. Alternatively, the thermal insulating material can be provided as a separate element in an electrically heated smoking system.

[0017] As in the first aspect of the present invention, the electrical insulating substrate can be made very thin and its size reduced. Furthermore, some or all of the necessary electronic equipment, wiring, and connections can be incorporated as a heater on the same electrical insulating substrate. Moreover, the heater can be manufactured more directly and cost-effectively than some conventional heaters that require each heating element to be formed separately. The heater allows for a fairly flexible design, namely, conductive tracks can be easily arranged on the electrical insulating substrate to provide the desired and preferred heat distribution.

[0018] Preferably, the electric heating smoking system further includes electronic circuits arranged to control the supply of power from a power source to at least one heater.

[0019] Preferably, the power supply provides power to at least one heater based on a desired temperature. Preferably, the electric heating smoking system includes electronic circuitry arranged as such. Preferably, the desired temperature is a temperature at which the heater heats the aerosol-forming substrate but does not burn it.

[0020] Preferably, one or more conductive tracks have a resistance temperature coefficient characteristic such that one or more conductive tracks can act as resistance heaters and temperature sensors.

[0021] In one embodiment according to any aspect of the present invention, one or more conductive tracks comprise multiple parts, each of which can be separately connected to a power source. This offers several advantages. First, different parts are heated for different durations, thereby enhancing the smoking experience depending on the properties of the aerosol-forming substrate. Second, different parts are heated at different temperatures, also enhancing the smoking experience depending on the properties of the aerosol-forming substrate. Third, this allows specific parts of the heater to be conductive at any given time, thereby ensuring that only a portion of the aerosol-forming substrate is heated at any given time. This is considered advantageous because it means that each portion of the aerosol-forming substrate is heated only once and not reheated.

[0022] In one embodiment according to any aspect of the present invention, one or more conductive tracks comprise a single track of conductive material. A first end of the single track is connectable to a power source, and a second end of the single track is also connectable to a power source. In this case, the power source is also connectable to one or more central sections of the single track to provide a plurality of parts, each of which can be individually connected to the power source. In another embodiment according to any aspect of the present invention, one or more conductive tracks comprise a plurality of tracks of conductive material, each of which can be individually connected to a power source.

[0023] In both aspects of the present invention, the conductive track is arranged on the electrically insulating substrate in a configuration most suitable for heating the aerosol-forming substrate. Any number of configurations are available.

[0024] In a first embodiment of any aspect of the present invention, the electrically insulating substrate is rigid and arranged to be inserted into the aerosol-forming substrate. If the electrically insulating substrate is appropriately dimensioned and rigid, it can be inserted directly into the aerosol-forming substrate. The electrically insulating substrate can be reinforced to provide sufficient rigidity. In that case, if a thermal insulation material is provided, it can be provided to surround the aerosol-forming substrate.

[0025] In a second embodiment of any aspect of the present invention, the electrically insulating substrate is tubular and one or more conductive tracks are inside the tubular electrically insulating substrate. Such a configuration can be used as an external heater. The external heater can be used to surround or partially surround the aerosol-forming substrate. In one embodiment, the aerosol-forming substrate is solid and in the form of a cylindrical plug. In that case, preferably, the inner diameter of the external heater is the same as or slightly larger than the outer diameter of the aerosol-forming plug. In a second embodiment, if a thermal insulation material is provided, it is provided to surround the aerosol-forming substrate and the external heater. The thermal insulation material can be provided on the electrically insulating substrate and the external heater can be formed by rolling the electrically insulating substrate such that the conductive track faces the inside of the tube and the thermal insulation material faces the outside of the tube.

[0026] In a third embodiment of any aspect of the present invention, the electrical insulating substrate is tubular and one or more conductive tracks are on the outside of the tubular electrical insulating substrate. Such a configuration can be used as an internal heater. The internal heater can be inserted into the aerosol-forming substrate. In one embodiment, the aerosol-forming substrate is solid and includes a hollow tube of the aerosol-forming substrate. In that case, preferably, the outer diameter of the internal heater is the same as or slightly smaller than the inner diameter of the tube of the aerosol-forming substrate. In that case, if a thermal insulation material is provided, it is provided so as to surround the aerosol-forming substrate.

[0027] In both aspects of the present invention, at least one heater can include an end heater for heating an end of the aerosol-forming substrate, the end heater including one or more conductive tracks on an electrical insulating substrate. In one embodiment, the end heater includes a helical conductive track on a circular or substantially circular electrical insulating substrate.

[0028] In both embodiments of the present invention, the conductive track preferably comprises an electrical resistance material. More preferably, the conductive track is metallic. Most preferably, the conductive track comprises one or more of silver, platinum, copper, nickel, and palladium. Other materials are also available, for example, electrically "conductive" ceramics (such as molybdenum silicide), carbon, graphite, metal alloys, and composite materials made of ceramic and metallic materials. Such composite materials may include doped or undoped ceramics. A suitable example of a doped ceramic is doped silicon carbide. Suitable examples of metals include those listed above, as well as titanium, zirconium, and tantalum. Examples of suitable metal alloys include stainless steel-, nickel-, cobalt-, chromium-, aluminum-, titanium-, zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, and iron-containing alloys, as well as nickel-, iron-, cobalt-, and stainless steel-based superalloys, Timeta1®, and iron-manganese-aluminum-based alloys. Timeta1® is a registered trademark of Titanium Meta1s Corporation, located at Broadway, Suite, 4300, Denver, Corado, 1999. In composite materials, depending on the kinetics of energy transfer and the required external physicochemical properties, the electrical resistance material may optionally be embedded or encapsulated in an insulating material, or coated with an insulating material, or vice versa.

[0029] In both embodiments of the present invention, the conductive track can be plated with a protective layer. The conductive track can be plated with one or more of gold, nickel, and glass. Plating the conductive track can be advantageous when the conductive track contains materials that are easily oxidized or corroded in some way.

[0030] In both embodiments of the present invention, the electrical insulating substrate preferably comprises one or more of paper, glass, ceramic, anodized metal, coated metal, and polyimide. The ceramic may be alumina (Al2O3) or zircona (ZrO2). Other suitable materials may also be used.

[0031] In a first embodiment of any aspect of the present invention, at least one heater is formed by preparing an electrical insulating substrate, depositing conductive paste onto the electrical insulating substrate using a template to form a pattern of conductive paste, and drying the conductive paste to form conductive tracks.

[0032] In the first embodiment, the electrical insulating substrate can be any suitable electrical insulating material, but ceramic or anodized metal is preferred. In the first embodiment, the conductive paste can be any suitable paste, but preferably contains metal particles. The metal may be silver. The conductive paste may also contain a binder and a plasticizer.

[0033] In a second embodiment of any aspect of the present invention, at least one heater is formed by preparing an electrical insulating substrate, covering substantially the entire surface of the electrical insulating substrate with a conductive material, protecting each portion of the conductive material with a mask that forms a pattern of the conductive material, and removing the unprotected portions of the conductive material.

[0034] In the second embodiment, the electrical insulating substrate can be any suitable electrical insulating material, but polyimide is preferred. In the second embodiment, the conductive material can be any suitable material, but preferably includes a metal alloy. The metal may be copper. The conductive track can be plated with one or more protective layers. In one embodiment, a copper conductive track is plated with a first layer of nickel and a second layer of gold.

[0035] In a third embodiment of any aspect of the present invention, at least one heater is formed by preparing an electrically insulating substrate, covering the electrically insulating substrate with a metal film, covering the metal film with a layer of photoresist material, protecting portions of the photoresist material with a mask that forms a pattern of conductive paste, removing unprotected portions of the photoresist material using a light source and chemicals (the exposed photoresist material is dissolved in a specific solvent), removing portions of the metal film not protected by the photoresist material, and removing the remaining portions of the photoresist material to expose a metal film in the form of conductive tracks.

[0036] In the third embodiment, the electrical insulating substrate can be any suitable electrical insulating material, but ceramic is preferred. Most preferably, the substrate is alumina (Al2O3) or zircona (ZrO2). In the third embodiment, the metal film can be any suitable metal film, but platinum film is preferred. The conductive track can be plated with one or more protective layers. In one embodiment, the conductive track can be plated with a layer of glass.

[0037] In both aspects of the present invention, the aerosol-forming substrate preferably comprises a tobacco-containing material containing volatile tobacco flavor compounds released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may contain a non-tobacco material.

[0038] In both aspects of the present invention, the aerosol-forming substrate preferably further comprises an aerosol-forming agent. Examples of suitable aerosol-forming agents are glycerin and propylene glycol.

[0039] In both embodiments of the present invention, the aerosol-forming substrate is preferably a solid substrate. In a preferred embodiment, the aerosol-forming substrate comprises a tubular substrate having a cavity for housing at least one heater. The solid substrate may contain, for example, one or more powders, granules, pellets, flakes, spaghetti, strips, or sheets containing one or more of the following: herb leaves, tobacco leaves, tobacco vein fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, and effervescent tobacco. The solid substrate may be provided in bulk form or in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may contain additional tobacco or non-tobacco volatile flavor compounds released when the substrate is heated.

[0040] In both embodiments of the present invention, the solid aerosol-forming substrate may optionally be provided on or embedded therein on a thermally stable carrier. In a preferred embodiment, the carrier is a tubular carrier having a thin layer of the solid substrate deposited on its inner surface, its outer surface, or both. Such a tubular carrier may be formed from, for example, paper or paper-like material, a nonwoven carbon fiber mat, a low-mass open-mesh metal screen, or a perforated metal foil, or any other thermally stable polymer matrix. Alternatively, the carrier may take the form of powder, granules, pellets, flakes, spaghetti, strips, or sheets.

[0041] In both aspects of the present invention, the solid aerosol-forming substrate can be deposited on the surface of a carrier, for example, in the form of a sheet, foam, gel, or slurry. The solid aerosol-forming substrate can be deposited on the entire surface of the carrier or, alternatively, in a certain pattern, to deliver a non-uniform flavor during use.

[0042] In both aspects of the present invention, the carrier may alternatively be a nonwoven fiber or fiber bundle in which a tobacco compound is incorporated therein. The nonwoven fiber or fiber bundle may include, for example, carbon fibers, natural cellulose fibers, or cellulose derivative fibers.

[0043] In both aspects of the present invention, the aerosol-forming substrate may alternatively be a liquid substrate. When a liquid aerosol-forming substrate is provided, the electric heating smoking system preferably includes means for holding the liquid. For example, the liquid aerosol-forming substrate may be held in a container. Alternatively or additionally, the liquid aerosol-forming substrate may be absorbed into a porous carrier material. The porous carrier material may be made from any suitable absorbent plug or absorbent, such as foamed metal or plastic material, polypropylene, terylene, nylon fibers, or ceramic. The liquid aerosol-forming substrate may be held in the porous carrier material before use of the electric heating smoking system, or alternatively, the liquid aerosol-forming substrate material may be released into the porous carrier material at the time of use or immediately before use. For example, the liquid aerosol-forming substrate may be provided in capsule form. The capsule shell preferably melts when heated to release the liquid aerosol-forming substrate into the porous carrier material. The capsule may optionally contain solids in combination with the liquid.

[0044] When the aerosol-forming substrate is a liquid aerosol-forming substrate, the electric heating smoking system may further include means for heating small amounts of liquid at a time. Means for heating small amounts of liquid at a time may include, for example, a liquid passage communicating with the liquid substrate. The liquid aerosol-forming substrate is typically forced into the liquid passage by capillary force. At least one heater is preferably arranged so that during use only the small amount of liquid aerosol-forming substrate in the liquid passage, and not the liquid in the container, is heated and volatilized.

[0045] Alternatively or additionally, if the aerosol-forming substrate is a liquid aerosol-forming substrate, the electrically heated smoking system may further include an atomizer containing at least one heater in contact with the liquid aerosol-forming substrate source. In addition to the heater, the atomizer may include one or more electromechanical elements, such as piezoelectric elements. Additionally or alternatively, the atomizer may also include elements that utilize electrostatic, electromagnetic, or air effects. The electrically heated smoking system may further include a condensation chamber.

[0046] In both aspects of the present invention, the aerosol-forming substrate can be alternatively any other type of aerosol-forming substrate, such as a gaseous aerosol-forming substrate or any combination of various forms of aerosol-forming substrates.

[0047] In both embodiments of the present invention, the aerosol-forming substrate can be fully housed within the electric heating smoking system during operation. In this case, the user can inhale smoke from the mouthpiece of the electric heating smoking system. Alternatively, the aerosol-forming substrate can be partially housed within the electric heating smoking system during operation. In this case, the aerosol-forming substrate forms part of an individual article, and the user can inhale smoke directly from the individual article.

[0048] In both embodiments of the present invention, the electrically heated smoking system may further include a sensor that detects an airflow indicating that a user is inhaling smoke. In that embodiment, preferably, the sensor is connected to a power source, and the system is arranged to energize at least one heater when the sensor detects that a user is inhaling smoke. Alternatively, the system may further include a switch that can be manually activated by the user to initiate smoking.

[0049] In both embodiments of the present invention, the electrically heated smoking system preferably further includes a housing designed to be grasped by a user to receive an aerosol-forming substrate. The housing preferably accommodates any other components necessary for the system, such as at least one heater, a power supply, and electronic circuitry. In one embodiment, the housing includes a shell and a replaceable mouthpiece.

[0050] In both embodiments of the present invention, in one preferred embodiment, the power source is a DC voltage supply source. In one embodiment, the power source is a lithium-ion battery. Alternatively, the power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium phosphate battery.

[0051] Features described in relation to one aspect of the present invention may also be applicable to other aspects of the present invention. In particular, the features and advantages of one or more conductive tracks acting as both a resistance heater and a temperature sensor, as described in relation to the first aspect of the present invention, may also be applicable to the second aspect of the present invention. The features and advantages of thermal insulating materials, as described in relation to the second aspect of the present invention, may also be applicable to the first aspect of the present invention.

[0052] The present invention will be further described below, simply as an example, with reference to the attached drawings. [Brief explanation of the drawing]

[0053] [Figure 1a] This figure shows a first embodiment of a method for forming a heater for an electric smoking system. [Figure 1b] This figure shows a first embodiment of a method for forming a heater for an electric smoking system. [Figure 1c] This figure shows a first embodiment of a method for forming a heater for an electric smoking system. [Figure 1d] This figure shows a first embodiment of a method for forming a heater for an electric smoking system. [Figure 2a] This figure shows a second embodiment of a method for forming a heater for an electric smoking system. [Figure 2b] This figure shows a second embodiment of a method for forming a heater for an electric smoking system. [Figure 2c] This figure shows a second embodiment of a method for forming a heater for an electric smoking system. [Figure 2d] This figure shows a second embodiment of a method for forming a heater for an electric smoking system. [Figure 2e] This figure shows a second embodiment of a method for forming a heater for an electric smoking system. [Figure 3a] This figure shows a third embodiment of a method for forming a heater for an electric smoking system. [Figure 3b] This figure shows a third embodiment of a method for forming a heater for an electric smoking system. [Figure 3c] This figure shows a third embodiment of a method for forming a heater for an electric smoking system. [Figure 3d] This figure shows a third embodiment of a method for forming a heater for an electric smoking system. [Figure 3e] This figure shows a third embodiment of a method for forming a heater for an electric smoking system. [Figure 3f] This figure shows a third embodiment of a method for forming a heater for an electric smoking system. [Figure 4] This figure shows a first embodiment of a heater for use in an electrically heated smoking system. [Figure 5a] This figure shows a second embodiment of a heater for use in an electrically heated smoking system. [Figure 5b] This figure shows a second embodiment of a heater for use in an electrically heated smoking system. [Modes for carrying out the invention]

[0054] As described above, the present invention provides an electrically heated smoking system including a heater. The heater includes one or more conductive tracks on an electrically insulating substrate. The heater can be formed by several different manufacturing processes. Figures 1a to 1d show the first manufacturing process. Figures 2a to 2d show the second manufacturing process. Figures 3a to 3d show the third manufacturing process.

[0055] Figures 1a to 1d show a manufacturing process using a technique similar to that used in screen printing. This manufacturing process can be used in conjunction with the first or second aspects of the present invention. Referring to Figure 1a, first an electrical insulating substrate 101 is prepared. The electrical insulating substrate can include any suitable electrical insulating material such as ceramic, glass, or paper, such as MICA, but is not limited to the following. Alternatively, the electrical insulating substrate can include an electrical conductor that is insulated from the conductive track by oxidation or anodizing of its surface or both (as produced in Figure 1b and described below). An example is anodized aluminum. Alternatively, the electrical insulating substrate can include an electrical conductor to which an intermediate coating called a glaze is added. In this case, the glaze has two functions: to electrically insulate the substrate from the conductive track and to reduce bending of the substrate. Folds present in the electrical insulating substrate can lead to cracks in the conductive paste (applied in Figure 1b and described below), which can cause damage to the resistor.

[0056] Referring to Figure 1b, the electrical insulating substrate is securely held in place, for example, by vacuum, while the metal paste 105 is coated onto the electrical insulating substrate using notches 107. Any suitable metal paste can be used, but as an example, the metal paste is silver paste. In a particularly advantageous example, the paste contains 20% to 30% binder and plasticizer, and 70% to 80% metal particles, typically silver particles. The notches 107 provide a template for the desired conductive track. After the metal paste 05 has been coated onto the electrical insulating substrate 101, the electrical insulating substrate and paste are fired, for example, in a sintering furnace. In a first firing phase between 200°C and 400°C, the organic binder and solvent are burned out. In a second firing phase between 350°C and 500°C, the metal particles are sintered.

[0057] Referring to Figure 1c, the electrical insulating substrate 101 results in having one or more conductive tracks 103 on it. One or more conductive tracks include heating resistors and necessary connection pads.

[0058] Finally, the electrical insulating substrate 101 and the conductive track 103 are formed into a suitable shape for use as a heater in an electrically heated smoking system. Referring to Figure 1d, the electrical insulating substrate 101 can be wound into a tubular shape (Figure 1d(i)) such that the conductive track is located inside the electrical insulating substrate. In this case, the tube can function as an external heater for a solid plug of aerosol-forming material. The inner diameter of the tube can be the same as or slightly larger than the diameter of the aerosol-forming plug. Alternatively, the electrical insulating substrate 101 can be wound into a tubular shape (Figure 1d(ii)) such that the conductive track is located outside the electrical insulating substrate. In this case, the tube can function as an internal heater and can be inserted directly into the aerosol-forming substrate. This works well when the aerosol-forming substrate takes the form of a tube of tobacco material, such as a tobacco mat. In this case, the outer diameter of the tube can be the same as or slightly smaller than the inner diameter of the aerosol-forming substrate. Alternatively, if the electrical insulating substrate is sufficiently rigid or reinforced in some way, some or all of the electrical insulating substrate and conductive tracks can be used directly as internal heaters by simply inserting the electrical insulating substrate and conductive tracks directly into the aerosol-forming substrate (Figure 1d(iii)).

[0059] Figures 2a to 2e show a second manufacturing process for a heater for an electrically heated smoking system. This manufacturing process can be used in conjunction with the first or second embodiment of the present invention. This manufacturing process is based on PCB manufacturing technology. Referring to Figure 2a, first an electrical insulating substrate 201 is prepared. Here again, the electrical insulating substrate can include any suitable electrical insulating material. In this example, the electrical insulating substrate 201 contains polyimide.

[0060] Referring to Figure 2b, secondly, a metal foil 205 is added substantially over the entire electrical insulating substrate 201. This can be achieved by lamination or by a physical vapor deposition (PVD) process followed by chemical reaction electrical reinforcement. Any suitable metal can be used, but in one example, the metal foil is copper. Copper has the advantage of a high temperature coefficient of resistance. This is considered to mean that it is relatively easy to use the conductive track as a temperature sensor and as a heater. This will be explained in more detail below. Other metals can also be used, but for example, nickel or platinum can be used, although this is not limited to the following.

[0061] After the metal foil 205 is added to the electrical insulating substrate, unwanted areas of copper are removed using subtraction. Referring to Figure 2c, a mask 207 is typically used in combination with chemical etching, which dissolves the copper in all areas not protected by the mask. This results in the device shown in Figure 2c, which includes an electrical insulating substrate 201 with conductive areas 209.

[0062] Referring to Figure 2d, the conductive area 209 can then be plated. Figure 2d shows one conductive area 209 for simplicity. Plating is advantageous when using copper because copper oxidizes rapidly. If an oxide layer has already formed, it can be difficult to solder the copper to form the required connections. In this example, the conductive area 209 is plated with a double layer consisting of a first layer 211 of nickel followed by a second layer 213 of gold. The result is an electrical insulating substrate 201 having one or more conductive tracks 203 thereon. One or more conductive tracks include heating resistors and the required connection pads.

[0063] Finally, the electrical insulating substrate 201 and the conductive track 203 are formed into a suitable shape for use as heaters in an electrically heated smoking system. Referring to Figure 2e, the electrical insulating substrate 201 can be rolled into a tubular shape such that the conductive track 203 is located inside the electrical insulating substrate (Figure 2e(i)). In this case, the tube can function as an external heater for the aerosol-forming substrate. Alternatively, the electrical insulating substrate 201 can be rolled into a tubular shape such that the conductive track is located outside the electrical insulating substrate (Figure 2e(ii)). In this case, the tube can function as an internal heater and can be inserted directly into the aerosol-forming substrate. Alternatively, if the electrical insulating substrate is sufficiently rigid or reinforced in some way, some or all of the electrical insulating substrate and conductive track can be used as an internal heater simply by inserting the electrical insulating substrate and conductive track directly into the aerosol-forming substrate (Figure 2e(iii)).

[0064] It should be noted that the method described in Figures 2a to 2e can also be used to form an additional thermal insulating reflective layer. This will be described in detail below.

[0065] Figures 3a to 3e show a third manufacturing step for a heater for an electrically heated smoking system. This manufacturing step can be used in conjunction with the first or second embodiment of the present invention. This manufacturing step is based on photolithography techniques. Referring to Figure 3a, first an electrical insulating substrate 301 is prepared. Again, the electrical insulating substrate can include any suitable electrical insulating material. In this example, the electrical insulating substrate 301 includes, but is not limited to, thick ceramics such as alumina (Al2O3) or zircona (ZrO2).

[0066] Referring to Figure 3b, the structured metal film 305 is formed on the electrical insulating substrate 301. Any suitable metal can be used, but in this example, the metal film is platinum.

[0067] Referring to Figure 3c, the photoresist layer 307 is then added on the metal film 305. The photoresist layer can be added by any suitable technique, such as spin coating, but is not limited to the following.

[0068] Referring to Figure 3d, unwanted areas of the photoresist are removed. This is achieved by exposing the photoresist to a high-intensity light ray from the light source 311 using a mask 309. A chemical reaction occurs in the exposed areas of the photoresist, thereby allowing these layers to be removed by a chemical agent called a developer.

[0069] With the photoresist removed in the unprotected areas, the metal film 305 is etched by wet or dry etching. This dissolves the metal film in all areas not protected by the photoresist. With the metal etched, any remaining photoresist is removed by a solvent. This results in the device shown in Figure 3e, which includes an electrically insulating substrate 301 with conductive areas 313.

[0070] Referring to Figure 3f, finally, the electrical insulating substrate 301 and the conductive area 313 can be optionally covered with a protective layer 315 to prevent corrosion or oxidation of the conductive area. In this example, the protective layer is a glass layer. The result is an electrical insulating substrate 301 having one or more conductive tracks thereon. One or more conductive tracks include heating resistors and necessary connection pads.

[0071] This heater can be mounted within an electrically heated smoking system using a special frame, such as a metal clamp, or the heater can be an integrated part of a monolithic ceramic base located within the electrically heated smoking system.

[0072] Figures 4, 5a, and 5b show two alternative embodiments of the heater of the present invention.

[0073] Figure 4 shows a first embodiment of a heater used with an aerosol-forming substrate. In Figure 4, the heater 400 includes a flat, rigid electrically insulating substrate 401 having conductive tracks 403 thereon (the heater can be in the form shown in Figure 1d(iii) or Figure 2e(iii)). The conductive tracks can be connected to a power source (not shown) through a connector 405. The heater 400 can be inserted directly into the plug of the aerosol-forming substrate shown schematicly 407. The heater shown in Figure 4 can be used in either the first or second embodiment of the present invention. If the conductive tracks have suitable temperature coefficient of resistance characteristics, they can act as resistance heaters and temperature sensors. The heater can be combined with a thermal insulating material to thermally insulate at least one heater from the outside of the electrically heated smoking system used with it.

[0074] Figures 5a and 5b show a second embodiment of the heater. In Figures 5a and 5b, the heater includes an electrical insulating substrate 501. A conductive track 503 is located on a first portion 509 of the electrical insulating substrate. The conductive track 503 is connectable to a power source (not shown) through a connector 505. On a second portion 511 of the electrical insulating substrate 501, a thermal insulating reflective honeycomb structure 507 is formed on the electrical insulating substrate. The heater in Figure 5a is designed to be wound in a tube from left to right, with the portion 509 of the electrical insulating substrate having the conductive track on the inside and the portion 511 of the electrical insulating substrate having the thermal insulating honeycomb structure 507 on the outside. Preferably, the thermal insulating material is also highly reflective. The resulting heater is schematically shown in Figure 5b. The honeycomb structure is then used to thermally insulate the heater and may preferably be metal. The heater shown in Figure 5b can be used as an external heater with the thermal insulating reflective honeycomb structure 507 facing outwards to insulate the heater from the outside of the electric heated smoking system used with it. This reduces heat loss and protects the user's hands from burns.

[0075] In Figures 5a and 5b, the thermally insulating reflective honeycomb structure is shown as an integral part of the heater. Alternatively, the honeycomb structure can be individually formed and used as independent elements in an electrically heated smoking system. For external heaters, the honeycomb structure can be wrapped around an electrically insulating substrate and conductive tracks. For internal heaters, the honeycomb structure can be provided around an aerosol-forming substrate. Furthermore, alternative structural arrangements for thermal insulating materials are possible.

[0076] The heaters shown in Figures 5a and 5b can also be used in a first aspect of the present invention, namely, they can act as resistance heaters and temperature sensors if the conductive tracks have appropriate resistance temperature coefficient characteristics.

[0077] As already mentioned above, the manufacturing process shown in Figures 2a to 2e can also be used to create the honeycomb structure 507. Individual areas of the electrical insulating substrate can be plated in a manner similar to that shown in Figure 2d. Once the underlying area is subsequently melted or removed by other means, the plating will form air cavities that provide thermal insulation. In a preferred configuration, the air cavities are provided within the honeycomb structure, but other configurations are also possible. Furthermore, using several layers of the thermal insulating structure, for example by winding or stacking several layers, provides maximum thermal insulation. In an advantageous embodiment, the plating may include only one layer of gold. Gold is particularly useful because it will reflect heat inward towards the electric heating smoking system, further reducing heat loss. Alternatively, the plating may include one layer of another metal, such as silver. Alternatively, the plating may include two layers, similar to that shown in Figure 2d.

[0078] Using a heater that includes conductive tracks formed on an electrically insulating substrate offers several advantages. The size of the components required for an electrically heated smoking system can be reduced. This reduces the overall size of the electrically heated smoking system. Furthermore, the electrically insulating substrate can be made very thin, allowing for further size reduction. In addition, some or all of the necessary electronics, wiring, and connections can be incorporated as part of the heater on the same electrically insulating substrate.

[0079] In addition, the heater can be manufactured more directly and cost-effectively than some conventional heaters that require each heating element to be formed separately. The heater offers a considerably more flexible design, meaning that the conductive tracks can be placed directly on the electrical insulating substrate to provide the desired and preferred heat distribution.

[0080] Furthermore, assuming that the material used for the conductive track has appropriate resistance-temperature coefficient characteristics, the conductive track can function as both a resistance heater and a temperature sensor. This eliminates the need for a separate temperature sensor, further reducing the size of the electric heating smoking system. This will be explained in more detail below.

[0081] The temperature coefficient of resistance is a measure of the change in resistance with respect to a given temperature change. The general formula is given by the following equation. R=R0(1+αT) Here, R is the resistance, R0 is the resistance at a given temperature (typically 0°C), T is the temperature, and α is the temperature coefficient of resistance. The temperature dependence of the conductor is substantially linear.

[0082] One method involves measuring the voltage across a conductive track and the current flowing through it, thereby determining its resistance. Then, assuming R0 and α (both known for the given material) are known, the temperature can be determined. That is, the conductive track can function as both a temperature sensor and a resistance heater.

[0083] The temperature coefficient of resistance α of a material must be reasonably reliable; that is, it must not fluctuate significantly over time or under certain conditions. Furthermore, using a material with a large temperature coefficient of resistance α can be advantageous because it means that relatively small changes in temperature result in large changes in resistance. Materials with large values ​​of α include platinum, nickel, and copper.

[0084] 1. An electrically heated smoking system for receiving an aerosol-forming substrate, A heater for heating a substrate to form an aerosol, A power supply for supplying power to at least one of the heaters, Includes, The at least one heater includes one or more conductive tracks on an electrically insulating substrate, the one or more conductive tracks having a resistance temperature coefficient characteristic such that the one or more conductive tracks can function as both a resistance heater and a temperature sensor. A system characterized by the following features. 2. The electric heating smoking system according to claim 1, characterized in that the power supply provides power to at least one heater based on the temperature and a desired temperature sensed by the one or more conductive tracks. 3. The electric heating smoking system according to claim 2, characterized in that the desired temperature is a temperature at which the heater heats the aerosol-forming substrate but does not burn it. 4. An electrically heated smoking system according to any one of 1 to 3, further comprising a thermal insulating material for insulating at least one of the heaters. 5. An electrically heated smoking system for receiving an aerosol-forming substrate, A heater having one or more conductive tracks on an electrically insulating substrate for heating the substrate to form an aerosol, A power supply for supplying power to at least one of the heaters, A thermal insulating material for insulating at least one of the heaters, A system characterized by including 6. The electrically heated smoking system according to claim 5, characterized in that the one or more conductive tracks have a resistance temperature coefficient characteristic such that the one or more conductive tracks can act as a resistance heater and a temperature sensor. 7. The electric heated smoking system according to any one of 1 to 6, characterized in that the one or more conductive tracks include a plurality of parts, each of which can be separately connected to the power supply. 8. The electrically heated smoking system according to any one of 1 to 7, characterized in that the electrically insulating substrate is a rigid body and is arranged to be inserted into the aerosol-forming substrate. 9. The electrically heated smoking system according to any one of 1 to 7, characterized in that the electrical insulating substrate is tubular, and the one or more conductive tracks are located inside the tubular electrical insulating substrate. 10. The electrically heated smoking system according to any one of 1 to 7, characterized in that the electrical insulating substrate is tubular, and the one or more conductive tracks are located outside the tubular electrical insulating substrate. 11. The electrically heated smoking system according to any one of 1 to 10, characterized in that the at least one heater includes an end heater having one or more conductive tracks on an electrically insulating substrate for heating the end of the aerosol-forming substrate. 12. The conductive track comprises one or more of silver, platinum, copper, nickel, and palladium. The conductive track is plated with one or more of gold, nickel, and glass. The electrical insulating substrate comprises one or more of the following: paper, glass, ceramic, anodized metal, coated metal, and polyimide. An electrically heated smoking system according to any one of claims 1 to 11, characterized in that it is at least one of the following: 13. A heater for use in an electric heating smoking system, One or more conductive tracks on an electrical insulating substrate, Includes, The one or more conductive tracks have a resistance temperature coefficient characteristic such that the one or more conductive tracks can act as both a resistance heater and a temperature sensor. A heater characterized by the following features. 14. Use of a heater in an electrically heated smoking system, The heater includes one or more conductive tracks on an electrically insulating substrate, and the one or more conductive tracks have resistance temperature coefficient characteristics such that the one or more conductive tracks can act as both a resistance heater and a temperature sensor. Uses a heater characterized by the following features. 15. Thermal insulating material for use in an electrically heated smoking system having a heater with one or more conductive tracks on an electrically insulating substrate. [Explanation of symbols]

[0085] 401 Electrical insulating substrate 403 Conductive Track 405 Conductive track connection 407 Plug for aerosol-forming substrate

Claims

1. An electrically heated smoking system configured to removably receive a solid aerosol-forming substrate in the form of a plug, wherein the electrically heated smoking system is At least one heater for heating an aerosol-forming substrate to form an aerosol, wherein the at least one heater includes one or more conductive tracks on an electrically insulating substrate, the electrically insulating substrate is made of polyimide and is flexible enough to be wound, and the heater is formed of the electrically insulating substrate wound in a tubular shape, A power supply for supplying power to at least one of the heaters and maintaining the heater at a desired temperature, Includes, The solid aerosol-forming substrate forms a part of an article separate from the heater. When the solid aerosol-forming substrate is received into the smoking system, the plug-like form of the solid aerosol-forming substrate is received within the tubular form of the heater. During operation, the user directly inhales smoke from the aforementioned separate item. The electric heating smoking system further includes an electronic circuit arranged to control the supply of power from the power source to the at least one heater, The electronic circuit is configured to receive a feedback signal indicating the temperature of the one or more conductive tracks, so as to enable the electronic circuit to maintain the one or more conductive tracks at a desired temperature. The aforementioned one or more conductive tracks include a plurality of parts, each of which can be separately connected to the power supply. An electrically heated smoking system characterized by the following features.

2. The electrically heated smoking system according to claim 1, characterized in that the one or more conductive tracks are arranged in a pattern on a continuous surface of the electrically insulating substrate, the covered portion of the surface is covered by the one or more conductive tracks, and the uncovered portion of the surface is located between the covered portions of the electrically insulating substrate.

3. The electrically heated smoking system according to claim 1 or 2, further comprising a temperature sensor for providing the aforementioned feedback signal.

4. The electrically heated smoking system according to claim 1 or 2, further comprising a protective layer covering one or more of the aforementioned conductive tracks.

5. The electrically heated smoking system according to claim 4, characterized in that the one or more conductive tracks consist of a single track.

6. The electrically heated smoking system according to claim 1 or 2, further comprising an electronic circuit arranged to control the supply of power from the power source to the at least one heater such that different portions of the one or more conductive tracks are heated for different durations, heated at different temperatures, or heated at different temperatures for different durations.

7. The electric heating smoking system according to claim 5, characterized in that the power supply is connected to the central compartment of the single track.

8. The electric heating smoking system according to claim 1 or 2, characterized in that the system includes an aerosol-forming substrate containing a tobacco-containing material that contains volatile tobacco flavor compounds released from the aerosol-forming substrate when heated.

9. A method for manufacturing an electrically heated smoking system configured to removably receive a solid aerosol-forming substrate in the form of a plug, wherein the manufacturing method is: A step of forming one or more conductive tracks on a polyimide substrate that is flexible enough to be wound, The process of winding the polyimide substrate into a tubular shape together with one or more of the aforementioned conductive tracks, The steps include connecting a power supply to one or more of the aforementioned conductive tracks, The step of providing an electronic circuit configured to control the supply of power from the power source to the one or more conductive tracks in order to maintain the one or more conductive tracks at a desired temperature, Includes, The solid aerosol-forming substrate forms a portion of an article separate from the polyimide substrate. When the solid aerosol-forming substrate is received into the smoking system, the plug of the solid aerosol-forming substrate is received within the tubular form of the polyimide substrate. During operation, the user directly inhales smoke from the aforementioned separate item. The electronic circuit is further configured to receive a feedback signal indicating the temperature of one or more conductive tracks, and to control the power supply from the power source to the one or more conductive tracks in order to maintain the one or more conductive tracks at a desired temperature based on the feedback signal. The aforementioned one or more conductive tracks include a plurality of parts, each of which can be separately connected to the power supply. A method characterized by the following:

10. The method according to 9, characterized in that the step of forming one or more conductive tracks includes the step of adding foil over the entire surface of the polyimide substrate, and then removing a portion of the foil so that one or more conductive tracks remain.

11. The method according to 9 or 10, characterized in that the step of forming one or more conductive tracks includes a step of forming the one or more conductive tracks in a pattern on a continuous surface of the polyimide substrate such that the covered portions of the polyimide substrate are covered by the one or more conductive tracks and the uncovered portions of the polyimide substrate are located between the covered portions of the polyimide substrate.

12. The method according to 9 or 10, further comprising the step of adding a protective layer on one or more conductive tracks.

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