Flexible cover for a charging or holding case of an aerosol-generating device
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- PHILIP MORRIS PRODUCTS SA
- Filing Date
- 2023-08-30
- Publication Date
- 2026-07-08
AI Technical Summary
Existing charging or holding cases for aerosol-generating devices require frequent use of USB charging adapters for recharging, and they lack efficient heat dissipation and electromagnetic shielding, which can lead to reduced charging efficiency and potential overheating.
A flexible cover with an attachment portion and a rigid portion comprising a stack of layers, including an antenna coil for wireless charging, a heat dissipation layer (preferably with graphite) for improved thermal conductivity, and an electromagnetic shielding layer (using nanocrystalline material or FeCo50 alloy) to enhance charging efficiency and prevent overheating.
The flexible cover allows for wireless charging without the need for USB adapters, improves charging efficiency through effective heat dissipation and electromagnetic shielding, and provides a user-replaceable accessory for decorative and personalization purposes.
Smart Images

Figure CN2023115901_06032025_PF_FP_ABST
Abstract
Description
Flexible cover for a charging or holding case of an aerosol-generating device
[0001] The present disclosure relates to a flexible cover for a charging or holding case of an aerosol generating device, and a corresponding aerosol-generation system including the charging or holding case, and the aerosol generating device.
[0002] Different types of aerosol-generating devices are known. For example, aerosol-generating devices according to a heat-not-burn type generally comprise a device battery, control electronics, and an electric heater for heating an aerosol-generating article to generate aerosol for consump-tion by a user. The aerosol-generating article may comprise an aerosol-forming substrate, such as a tobacco segment or a tobacco plug, and the electric heater contained within the aerosol-generating device penetrates into or is located around the aerosol-forming substrate, when the aerosol-generating article is received in the aerosol-generating device. Another type of aerosol-generating devices according to a vaporizer type may comprise a device battery to heat aerosol-generating liquid from a cartridge to provide aerosol for consumption by a user.
[0003] Aerosol-generating devices are also used as pharmaceutical-type atomizers or aerosol-generators for generating inhalable pharmaceutical ingredients.
[0004] WO 2021 / 074420 discloses a holder for an elongate aerosol-generating device. The holder defines a docking space for accommodating the aerosol-generating device. The aerosol-gener-ating device can be accommodated in the docking space for protection and for recharging of a device battery of the aerosol-generating device with power from a primary battery of the holder. The holder comprises a cover that is moveable between a covering position, in which the cover covers at least a portion of the docking space, and a non-covering position.
[0005] Commonly known charging or holding cases are provided with a USB charging adapter, to which a cable can be connected and plugged into a power outlet, to recharge the primary battery.
[0006] According to a first aspect of the present invention, there is provided a flexible cover for a charging or holding case of an aerosol-generating device. The cover comprises an attachment portion and a rigid portion. The cover may comprise at least one flexible portion. The flexible portion may be adjacent to the attachment portion. The flexible portion may be adjacent to the rigid portion. The flexible portion may be located between the rigid portion and the attachment portion.
[0007] The attachment portion is for removably attaching the cover to the charging or holding case. The rigid portion comprises a stack of layers. The stack of layers includes an antenna coil for wirelessly receiving power for wireless charging of the charging or holding case, a heat dissipation layer, and an electromagnetic shielding layer. Therefore, a user does not have to use a USB charging adapter every time for recharging the primary battery. Furthermore, the cover as a whole can be removably attached to and detached from the charging or holding case, thereby allowing a user to change the outer cover, if the outer cover is worn. This may also enable to use the cover as a user-replaceable accessory. Thus, the cover may additionally serve for decorative and per-sonalization purposes. The heat dissipation layer and the electromagnetic shielding layer improve charging efficiency of the wireless charging.
[0008] The flexible cover may be elastically or plastically deformable to be spread to be flat. When the flexible cover is spread to be flat, it may form a larger charging and device receiving surface, as compared to a situation where the wireless charging antenna is integrated into the charging or holding case.
[0009] The thermal heat conductivity of the heat dissipation layer may be superior compared to other layers of the stack of layers. The thermal heat conductivity of the heat dissipation layer may be superior compared to all other layers of the stack of layers. The heat dissipation layer may significantly improve heat spreading and dissipation. Thus, the heat dissipation layer may help heat, which is generated during wireless charging, to spread and dissipate, thereby improving charging efficiency.
[0010] The heat dissipation layer may comprise a metal. The metal may be any of aluminum, cop-per, silver, or gold or a combination thereof. Alternatively or additionally, the heat dissipation layer may comprise graphite. The heat dissipation layer may consist of graphite. Graphite may help heat, which is generated during wireless charging, to spread and dissipate. In addition, graphite may function as a receiver resistance reducer. Thus, graphite may improve charging efficiency.
[0011] A layer thickness of the heat dissipation layer may range from 0.1 mm to 0.8 mm. Preferably, the layer thickness of the heat dissipation layer may be 0.5 mm. The heat dissipation layer may comprise or consist of graphite and in addition, the layer thickness of the heat dissipation layer may range from 0.1 mm to 0.8 mm. The thicker the graphite layer is, the better the charging efficiency may be. Preferably, the heat dissipation layer may comprise or consist of graphite and in addition, the layer thickness of the heat dissipation layer is 0.5 mm.
[0012] The electromagnetic shielding layer may comprise a nanocrystalline material. In addition or alternatively, the electromagnetic shielding layer may comprise FeCo50 alloy. These materials have the characteristics of narrow and steep hysteresis loop, nearly reversible magnetization pro-cess, small hysteresis loss, low coercivity and high permeability. Thus, nanocrystalline material or FeCo50 alloy (or the combination thereof) may considerably help to reduce energy loss during wireless charging. The magnetic field generated during wireless power transmission may be con-centrated. This may maximize charging efficiency.
[0013] A layer thickness of the electromagnetic shielding layer may range from 0.01 mm to 1 mm. The electromagnetic shielding layer may be configured to cover at least a part of an area of the charging or holding case that is exposed to the antenna coil in a state, in which the flexible cover is attached to the charging or holding case. The electromagnetic shielding layer may be config-ured to cover the entire area of the charging or holding case that is exposed to the antenna coil in a state, in which the flexible cover is attached to the charging or holding case. This may increase charging efficiency.
[0014] The stack of layers may further include a stiffening layer. This may prevent the antenna coil from being bent, folded, creased, or distorted that could lead to breakage or tearing of part of the antenna coil. Thus, the stiffening layer may ensure charging efficiency. The stiffening layer may comprise a metal. Additionally or alternatively, the stiffening layer may comprise a plastic material. The stiffening layer may comprise polycarbonate (PC) , aluminum alloy, or stainless steel or a combination thereof. Preferably, the stiffening layer may comprise PC. This may prevent power loss during wireless power transmission, since PC hardly attracts additional current during wire-less power transmission. A layer thickness of the stiffening layer may range from 0.1 mm to 0.5 mm.The layer thickness of the stiffening layer may range from 0.3 mm to 0.4 mm.
[0015] The antenna coil may be glued on pressure-sensitive adhesives. A thickness of the antenna coil may be 1 mm. Thus, rigidity of the antenna coil may be ensured and distortion of the antenna coil may be suppressed.
[0016] The following stacking orders can be seen in a thickness direction of the cover, as refer-enced to a perpendicular direction towards the charging or holding case from an outer surface portion of the flexible cover. Seen in said thickness direction, the electromagnetic shielding layer may be disposed above the antenna coil. The heat dissipation layer may be disposed above the electromagnetic shielding layer. In a case, in which the stack of layers further includes a stiffening layer, the antenna coil may be disposed above the stiffening layer. Additionally or alternatively, the stiffening layer may be disposed above the heat dissipation layer.
[0017] The layers may be stacked in any of the following orders, seen in a thickness direction of the cover from an outer side of the cover that is configured to be directed to the exterior in a state, in which the cover is attached to the charging or holding case:
[0018] - outer stiffening layer, antenna coil, electromagnetic shielding layer, heat dissipation layer, inner stiffening layer;
[0019] - antenna coil, electromagnetic shielding layer, heat dissipation layer, stiffening layer;
[0020] - stiffening layer, antenna coil, electromagnetic shielding layer, heat dissipation layer.
[0021] The above layer arrangements may ensure an optimized functionality of each layer of the stack of layers. Thus, charging efficiency may be optimized.
[0022] The stack of layers may further include an electronic component that is configured to pro-vide information to a user. The electronic component may comprise a display screen. Additionally or alternatively, the electronic component may comprise at least one LED. The electronic compo-nent may be arranged on top of the stack of layers, when seen in a thickness direction of the cover from an inner side of the cover, wherein the inner side of the cover is configured to be directed to the charging or holding case in a state, in which the cover is attached to the charging or holding case. The information provided may be a wireless charging state. The wireless charg-ing state may be a battery capacity level. Additionally or alternatively, the wireless charging state may be a way of charging. Additionally or alternatively, the wireless charging state may be a charging progression. The information provided may reflect a positional alignment of the antenna coil with respect to a wireless power transmitter.
[0023] The cover may comprise a flexible wrap. The flexible wrap may be configured to be revers-ibly wrapped around at least a portion of the charging or holding case. The stack of layers may be fixed to the flexible wrap. The stack of layers may be partially embedded in the flexible wrap. The stack of layers may be entirely embedded in the flexible wrap. The flexible wrap may com-prise an inner layer, wherein the inner layer may be configured to face the charging or holding case in a state, in which the cover is attached to the charging or holding case. The flexible wrap may comprise an outer layer, wherein the outer layer may be configured to be exposed to an outer side of the cover in a state, in which the cover is attached to the charging or holding case. The flexible wrap may comprise a fabric, leather, faux leather, suede leather, faux suede leather, velvet material, felt-like material, fibrous material, multilayer 3D printed layer, embossed layer, fur or faux fur like material or polyurethane (PU) material or a combination thereof. The outer layer may comprise a fabric, leather, faux leather, suede leather, faux suede leather, velvet material, felt-like material, fibrous material, multilayer 3D printed layer, embossed layer, fur or faux fur like material or polyurethane (PU) material or a combination thereof. The outer layer may be semi-transparent, porous or reflective (or a combination thereof) , so that an underlying display screen or LEDs (or a combination thereof) can shine through the outer layer. The display screen or the LEDs may be at least partially embedded in the outer layer. The inner layer may comprise a fabric, leather, faux leather, suede leather, faux suede leather, velvet material, felt-like material, fibrous material, multilayer 3D printed layer, embossed layer, fur or faux fur like material or polyurethane (PU) material or a combination thereof. The inner layer may be semitransparent, porous or reflec-tive (or a combination thereof) , so that an underlying display screen or LEDs (or a combination thereof) can shine through the inner layer. The display screen or the LEDs may be at least partially embedded in the inner layer. The material of the inner layer may differ from the material of the outer layer. A layer thickness of the inner layer may range from 0.5 mm to 0.8 mm. A layer thick-ness of the outer layer may range from 0.5 mm to 0.8 mm. The layer thickness of the inner layer may differ from the layer thickness of the outer layer. The stack of layers may be sandwiched between the inner and outer layers. Any of the antenna coil, the heat dissipation layer, the elec-tromagnetic shielding layer and the stiffening layer may be merged with any of the inner and outer layers.
[0024] The attachment portion may comprise a self-alignment structure. The self-alignment struc-ture may be configured to prevent a misalignment between the cover and the charging or holding case. Thus, a correct orientation and correct alignment between the cover and the charging or holding case may be ensured. This may provide a proper mechanical alignment of the flexible cover with a cavity or opening that needs to be covered. Furthermore, the correct orientation and correct alignment between the cover and the charging or holding case may provide a proper electric interconnection of the flexible flap with the charging or holding case. Hence, wireless charging functionality of the flexible cover may be assured.
[0025] The self-alignment structure may comprise at least one attachment means. The attachment means may be a magnet, a metallic structure susceptible to magnetic interaction, or a snap-fit or press-fit structure (or a combination thereof) . Thus, connection robustness may be improved be-tween the cover and the charging or holding case. The self-alignment structure may comprise at least two attachment means. The attachment means may differ in size from each other. Addition-ally or alternatively, the attachment means may differ in shape from each other.
[0026] Additionally or alternatively, the attachment means may exhibit asymmetry with respect to a symmetry plane of the cover, wherein said symmetry plane is parallel to a thickness direction of the cover. The asymmetry may be caused by positioning of the attachment means. The attach-ment means may be magnets or metallic structures susceptible to magnetic interaction (or a com-bination thereof) , and the asymmetry may be established by means of polarity of the attachment means.
[0027] According to a second aspect of the present invention, there is provided a charging or hold-ing case for an aerosol-generating device. The charging or holding case comprises a cover ac-cording to the first aspect described above.
[0028] According to a third aspect of the present invention, there is provided an aerosol-generation system. The aerosol-generation system comprises an aerosol-generating device. The aerosol-generation system further comprises a charging or holding case according to the second aspect described above.
[0029] According to a fourth aspect of the present invention, there is provided a method for wireless charging of a charging or holding case for an aerosol-generating device. The method comprises a step of attaching a cover to the charging or holding case. The cover is a cover according to the first aspect described above.
[0030] According to a fifth aspect of the present invention, there is provided a use of a cover ac-cording to the first aspect described above for wireless charging of a charging or holding case.
[0031] The present disclosure comprises various aspects, embodiments, and examples. Features, advantages, and explanations disclosed with reference to any one of these aspects, embodi-ments, and examples may be combined with, or transferred to, any one of the other aspects, embodiments, and examples described herein.
[0032] The invention is defined in the claims. However, below there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.
[0033] Example Ex1: A flexible cover for a charging or holding case of an electronic device, partic-ularly for a charging or holding case of an aerosol-generating device, the cover comprising:
[0034] an attachment portion for removably attaching the cover to the charging or holding case; and
[0035] a rigid portion comprising a stack of layers,
[0036] wherein the stack of layers includes an antenna coil for wirelessly receiving power for wire-less charging of the charging or holding case, a heat dissipation layer, and an electromagnetic shielding layer.
[0037] Example Ex2: The cover according to Example Ex1, wherein the heat dissipation layer comprises at least one of the following features:
[0038] a. the heat dissipation layer comprises a metal, preferably aluminum, copper, silver, and / or gold;
[0039] b. the heat dissipation layer comprises graphite;
[0040] c. the heat dissipation layer consists of graphite;
[0041] d. a layer thickness of the heat dissipation layer ranges from 0.1 mm to 0.8 mm, pref-erably is 0.5mm.
[0042] Example Ex3: The cover according to Example Ex1 or Ex2, wherein the electromagnetic shielding layer comprises at least one of the following features:
[0043] a. the electromagnetic shielding layer comprises a nanocrystalline material, and / or comprises FeCo50 alloy;
[0044] b. a layer thickness of the electromagnetic shielding layer ranges from 0.01 mm to 1 mm.
[0045] Example Ex4: The cover according to any of Examples Ex1 to Ex3, wherein the stack of layers further includes a stiffening layer that comprises at least one of the following features:
[0046] a. the stiffening layer comprises a metal and / or plastic material;
[0047] b. the stiffening layer comprises polycarbonate (PC) , aluminum alloy, and / or stainless steel;
[0048] c. a layer thickness of the stiffening layer ranges from 0.1 mm to 0.5 mm, preferably from 0.3 mm to 0.4 mm.
[0049] Example Ex5: The cover according to any of Examples Ex1 to Ex4, wherein the antenna coil comprises at least one of the following features:
[0050] a. the antenna coil is glued on pressure-sensitive adhesives;
[0051] b. the thickness of the antenna coil is approximately 1 mm.
[0052] Example Ex6: The cover according to any of Examples Ex1 to Ex5, wherein the layers are stacked in any of the following orders, seen in a thickness direction of the cover, as referenced to a perpendicular direction towards the charging or holding case from an outer surface portion of the flexible cover:
[0053] a. outer stiffening layer, antenna coil, electromagnetic shielding layer, heat dissipa-tion layer, inner stiffening layer;
[0054] b. antenna coil, electromagnetic shielding layer, heat dissipation layer, stiffening layer;
[0055] c. stiffening layer, antenna coil, electromagnetic shielding layer, heat dissipation layer.
[0056] Example Ex7: The cover according to any of Examples Ex1 to Ex6, wherein the stack of layers further includes an electronic component that is configured to provide information to a user, wherein the electronic component comprises a display screen and / or LEDs.
[0057] Example Ex8: The cover according to the preceding Example Ex7, wherein the electronic component is arranged on top of the stack of layers, when seen in a thickness direction of the cover from an inner side of the cover, wherein the inner side of the cover is configured to be directed to the charging or holding case in a state, in which the cover is attached to the charging or holding case.
[0058] Example Ex9: The cover according to any of Examples Ex1 to Ex8, comprising a flexible wrap configured to be reversibly wrapped around at least a portion of the charging or holding case, wherein the stack of layers is fixed to, preferably partially embedded in, particularly preferably entirely embedded in the flexible wrap.
[0059] Example Ex10: The cover according to the preceding Example Ex9, wherein the flexible wrap comprises at least one of the following features:
[0060] a. an inner layer configured to face the charging or holding case in a state, in which the cover is attached to the charging or holding case;
[0061] b. an outer layer configured to be exposed to an outer side of the cover in a state, in which the cover is attached to the charging or holding case;
[0062] c. a fabric, leather, faux leather, suede leather, faux suede leather, velvet material, felt-like material, fibrous material, fur material, multilayer 3D printed layer, embossed layer, faux fur like material, and / or polyurethane (PU) material;
[0063] d. a layer thickness of the inner layer and / or outer layer ranges from 0.5 mm to 0.8 mm;
[0064] e. the stack of layers is sandwiched between the inner and outer layers;
[0065] f. any of the antenna coil, the heat dissipation layer, the electromagnetic shielding layer, the stiffening layer and the electronic component is merged with any of the inner and outer layers;
[0066] f. any of the inner and outer layers is semitransparent, porous and / or reflective, so that an underlying display screen and / or LEDs can shine through.
[0067] Example Ex11: The cover according to any of Examples Ex1 to Ex10, wherein the attach-ment portion comprises a self-alignment structure that is configured to prevent a misalignment between the cover and the charging or holding case.
[0068] Example Ex12: The cover according to the preceding Example Ex11, wherein the self-alignment structure comprises at least one attachment means, being a magnet, a metallic struc-ture susceptible to magnetic interaction, a snap-fit structure, and / or a press-fit structure.
[0069] Example Ex13: The cover according to the preceding Example Ex12, wherein the self-alignment structure comprises at least two attachment means, the attachment means
[0070] a. differing in size and / or shape from each other; and / or
[0071] b. exhibiting asymmetry with respect to a symmetry plane of the cover parallel to a thickness direction of the cover.
[0072] Example Ex14: The cover according to the preceding Example Ex13, wherein the asym-metry is caused by positioning of the attachment means.
[0073] Example Ex15: The cover according to Example Ex13 or Ex14, wherein the attachment means are magnets and / or metallic structures susceptible to magnetic interaction, and the asym-metry is established by means of polarity of the attachment means.
[0074] Example Ex16: A charging or holding case for an electronic device, the charging or holding case comprising a cover according to any of the preceding Examples Ex1 to Ex15.
[0075] Example Ex17: The charging or holding case according to Example Ex16, wherein the elec-tronic device is an aerosol-generating device.
[0076] Example Ex18: A system, comprising an electronic device and a charging or holding case according to the preceding Example Ex16.
[0077] Example Ex19: The system according to the preceding Example Ex18, wherein the elec-tronic device is an aerosol-generating device.
[0078] Example Ex20: A method for wireless charging of a charging or holding case for an elec-tronic device, the method comprising:
[0079] a. attaching a cover to the charging or holding case, the cover being a cover accord-ing to any of the preceding Examples Ex1 to Ex15;
[0080] b. wirelessly transmitting power to the antenna coil of the cover.
[0081] Example Ex21: Use of a cover according to any of the preceding Examples Ex1 to Ex15 for wireless charging of a charging or holding case.
[0082] Examples will now be further described with reference to the figures, in which:
[0083] Figure 1 shows a schematic perspective view of an aerosol-generating system;
[0084] Figure 2 shows a schematic perspective view of the aerosol-generating system, wherein a charging or holding case of the aerosol-generating system is shown in a partly disassembled state;
[0085] Figure 3 shows a perspective view of a flexible cover according to a first embodiment;
[0086] Figure 4 shows a perspective view of the flexible cover according to the first embodiment, wherein a flexible wrap and an upper stiffening layer are omitted;
[0087] Figure 5 shows an enlarged perspective view of a stack of layers of the flexible cover ac-cording to the first embodiment, wherein the flexible wrap and the upper stiffening layer are omit-ted;
[0088] Figure 6 shows a first layer arrangement along a thickness direction of the flexible cover;
[0089] Figure 7 shows a second layer arrangement along the thickness direction of the flexible cover;
[0090] Figure 8 shows a diagram, in which test results of the wireless power transmission efficiency of different sets of material combinations are illustrated;
[0091] Figure 9 shows a first example of a self-alignment structure.
[0092] Figure 10 shows a second example of the self-alignment structure.
[0093] Figure 11 shows a third example of the self-alignment structure.
[0094] Figure 12 shows a fourth example of the self-alignment structure.
[0095] Figure 13 shows a fifth example of the self-alignment structure.
[0096] Figure 14 shows a sixth example of the self-alignment structure.
[0097] Like features are indicated with like reference numerals throughout the claims.
[0098] Figure 1 shows an aerosol-generating system 1. The aerosol-generating system 1 com-prises an aerosol-generating device 3. The aerosol-generating device 3 can be a handheld elec-tronic device for heating a stick-shaped aerosol-generating article to produce aerosol for con-sumption by a user. The aerosol-generating device 3 comprises a receiving cavity 5 for receiving the aerosol-generating article. The aerosol-generating device 3 further comprises a heater 7 to heat the aerosol-generating article, in particular an aerosol-generating segment of the aerosol-generating article. The heater 7 may, for example, comprise a resistive heater element or an induction assembly configured to heat the aerosol-generating segment. The aerosol-generating device 3 further comprises a rechargeable device battery 9 for powering one or more functions of the aerosol-generating device 3. In particular, the device battery 9 powers the heater 7. In a var-iant, the aerosol-generating device 3 is a vaporizer type device, to vaporize a liquid having one or more active agents.
[0099] The aerosol-generating system 1 further comprises a charging or holding case 11. The charging or holding case 11 comprises a flexible cover 13. In Fig. 1, the charging or holding case 11 is shown with the flexible cover 13 in a configuration, in which the flexible cover 13 is in an attached to and wrapped around state. In this state, the charging or holding case 11 is in a closed state.
[0100] Figure 2 shows the charging or holding case 11 in a partly disassembled state. As shown in Fig. 2, the charging or holding case 11 further comprises a case body 31. The case body 31 defines a docking compartment (or holding cavity or opening) 33. The docking compartment 33 is configured to receive the aerosol-generating device 3. A user may store or place the aerosol-generating device 3 in the docking compartment 33 of the charging or holding case 11 between uses.
[0101] Furthermore, the charging or holding case 11 comprises a charging or holding case battery 35.The charging or holding case battery 35 is received in a battery compartment 37 defined by the case body 31. The charging or holding case battery 35 is in electrical contact with an electric battery interface of the charging or holding case 11. The electric battery interface is electrically connected to an electric device interface provided in the docking compartment 33. When the aer-osol-generating device 3 is received in the docking compartment 33, the aerosol-generating de-vice 3 can be electrically connected with the electric device interface to allow charging of the device battery 9 from the charging or holding case battery 35. Thus, the device battery 9 may be recharged between uses, while stored or placed in the docking compartment 33.
[0102] As further shown in Fig. 2, the charging or holding case 11 comprises a battery compart-ment cover 39. The battery compartment cover 39 is operable between a closed state and an open state. In the closed state, the battery compartment cover 39 prevents that the charging or holding case battery 35 within the battery compartment 37 is accessible to be removed. In the closed state, the battery compartment cover 39 is reversibly attached to the case body 31, for example, via a snap-fit connection. The snap-fit connection comprises structures 41 provided at the battery compartment cover 39 and corresponding counter-structures 43 provided at the case body 31. The open state is shown in Fig. 2. In the open state, the battery compartment cover 39 allows access to the battery compartment 37 to remove or insert the charging or holding case battery 35.
[0103] Moreover, the charging or holding case 11 comprises a housing part 45 attached to the case body 31. The housing part 45 may be made of metal, and forms at least part of an outer appearance of the charging or holding case 11.
[0104] The flexible cover 13 can be removably attached to the case body 31. For this purpose, the flexible cover 13 comprises an attachment portion 19. Fig. 3 shows the flexible cover 13 removed from the case body 31. The flexible cover 13 comprises a flexible wrap 15. The flexible wrap 15 comprises a free end 27 of the flexible cover 13. The flexible wrap 15 is configured to be reversibly wrapped around the case body 31, while the flexible cover 13 is attached to the case body 31 via the attachment portion 19.
[0105] At the free end 27 of the flexible wrap 15, a latch part 29 is provided. The latch part 29 is configured to reversibly attach to the case body 31. Preferably, the latch part 29 comprises a magnet incorporated into the flexible cover 13, or attached to the flexible cover 13. The free end 27 may be attached to the case body 31 to bring the charging or holding case 11 into a closed configuration. The closed configuration is shown in Fig. 1.
[0106] The flexible wrap 15 includes an inner side surface 47 and an outer side surface 49. In a state, in which the flexible cover 13 is attached to the case body 31 in the configuration shown in Fig. 1, the inner side surface 47 faces the case body 31. Additionally, in this state, the outer side surface 49 is directed to the exterior, i.e. it is exposed to an outer side of the flexible cover 13.
[0107] The inner side surface 47 and the outer side surface 49 are formed by an inner layer 51 and an outer layer 52, respectively. The inner layer 51 and the outer layer 52 may be formed of the same material or may be formed of different materials. For example, the outer layer 52 com-prises fabric or polyurethane (PU) , and the inner layer 51 comprises a micro-fabric. Furthermore, as an example, a layer thickness of the outer layer 52 may be 0.65 mm, and a layer thickness of the inner layer 51 may be 0.55 mm.
[0108] Fig. 4 shows a state of the flexible cover 13, in which the flexible wrap 15 and an outer stiffening layer 53 are omitted. As can be seen from this figure, a first stiffening element 63 is embedded at the free and 27 of the flexible wrap 15. The first stiffening element 63 may be em-bedded between the inner layer 51 and the outer layer 52. The first stiffening element 63 may also be merged with any of the inner layer 51 and the outer layer 52. The first stiffening element 63 is formed of a plastic material, and enhances stiffness and durability of the free end 27.
[0109] Furthermore, at least within a wireless charging area 61, the flexible cover 13 comprises a stack of layers 17. In the embodiment depicted in Figs. 2 and 3, the stack of layers 17 is embedded in the flexible wrap 15. In Fig. 2, the stack of layers 17 is indicated by broken lines, which are located within the broken lines illustrating the wireless charging area 61. As can be seen in Fig. 3, the stack of layers 17 is embedded in the flexible wrap 15, so that a slight protrusion is formed in the wireless charging area 61. Alternatively, the stack of layers 17 may be embedded in the flexible wrap 15, so that the outer side surface 49 of the flexible cover 13 within the wireless charging area 61 is flush with the outer side surface 49 around the wireless charging area 61.
[0110] Fig. 5 shows an enlarged perspective view of the stack of layers 17, wherein the flexible wrap 15 and the outer stiffening layer 53 are omitted. As shown in Figs. 4 and 5, the stack of layers 17 comprises an inner stiffening layer 60, an antenna coil 55, an electromagnetic shielding layer 57 and a heat dissipation layer 59. The inner stiffening layer 60, the antenna coil 55, the electromagnetic shielding layer 57 and the heat dissipation layer 59 at least partially overlap each other.
[0111] An exemplary first layer arrangement of the layers of the flexible cover 13 within the wireless charging area 61 is shown in Fig. 6 along a thickness direction 200 of the flexible cover 13. As shown in Fig. 6, the stack of layers 17 is entirely embedded between the inner layer 51 and the outer layer 52 of the flexible wrap 15. The stack of layers 17 comprises the outer stiffening layer 53, the antenna coil 55, the electromagnetic shielding layer 57, the heat dissipation layer 59 and the inner stiffening layer 60. These layers are directly stacked on each other in this order along the thickness direction 200 of the flexible cover 13, starting from the outer layer 52. A coupling agent, such as an adhesive, may be applied between some or all of these layers.
[0112] As already noted above, the aspects of the present invention are not limited to the layer arrangement depicted in Fig. 6. In particular, any of the inner stiffening layer 60 and the outer stiffening layer 53 may be omitted. Furthermore, the inner stiffening layer 60 may be merged with the inner layer 51. For example, the inner stiffening layer 60 may be merged with the inner layer 51 such that the inner stiffening layer 60 forms at least a part of the inner side surface 47. In this case, the inner stiffening layer 60 is preferably flush with the remaining part of the inner layer 51. Additionally or alternatively, the outer stiffening layer 53 may be merged with the outer layer 52. For example, the outer stiffening layer 53 may be merged with the outer layer 52 such that the outer stiffening layer 53 forms at least a part of the outer side surface 49. In this case, the outer stiffening layer 53 is preferably flush with the remaining part of the outer layer 52.
[0113] An exemplary second layer arrangement of the layers of the flexible cover 13 within the wireless charging area 61 is shown in Fig. 7 along the thickness direction 200 of the flexible cover 13.Apart from their differences described in the following, the explanations provided above with respect to the first layer arrangement also apply to the second layer arrangement.
[0114] As shown in Fig. 7, the stack of layers 17 may additionally comprise a display 54. The display 54 is disposed as a top layer of the stack of layers 17, or at least partially embedded into the layer below, e.g. the outer stiffening layer 53. In the fully embedded state depicted in Fig. 7, the display 54 is sandwiched between the outer layer 52 and the outer stiffening layer 53. In this state, the thickness and the material of the outer layer 52 are chosen in order to hide the display 54, such that the electronic component forming the display 54 cannot be seen from the outer side of the flexible cover 13. At the same time, the thickness and the material of the outer layer 52 are chosen in order to allow the display 54 to shine through, thereby providing information to a user. For example, the outer layer 52 may be a semitransparent, porous or reflective layer (or a com-bination thereof) . The outer layer 52 may comprise a fabric, leather, faux leather, suede leather, faux suede leather, velvet material, felt-like material, fibrous material, fur or faux fur like material, multilayer 3D printed layer, embossed layer or polyurethane (PU) material or a combination thereof.
[0115] As exemplary material for any of the above stiffening layers 53 and 60, polycarbonate (PC) or stainless steel or aluminum alloy may be used. These materials impart a stable support struc-ture for the antenna coil 55. In particular, including at least one stiffening layer 53, 60 prevents that the antenna coil 55 bends, folds, creases or is distorted. Otherwise, a bent, folded, or dis-torted coil would considerably lower efficiency of wireless power transmission, and could lead to a breakage or tearing of one or more windings of the coil, which could cause malfunctioning and can be hazardous to cause electric shocks and fire.
[0116] For the sake of an improved heat dissipation, the heat dissipation layer 59 comprises graph-ite, aluminum, copper, silver or gold (or a combination thereof) . For optimized heat dissipation, it is preferred that the heat dissipation layer 59 comprises graphite.
[0117] In a test, different sets of material combinations were tested concerning their effect on the efficiency of wireless power transmission. The test was performed in room temperature. In the test, a transmitter board was supplied with DC voltage, and a receiver board was connected with a load. The input DC voltage and current and output DC voltage and current were measured.
[0118] The test results are depicted in the diagram shown in Fig. 8. As a layer arrangement to be examined, the first layer arrangement (shown in Fig. 6) was applied. For each set, the inner layer 51 and the outer layer 52 comprised a fabric. As the antenna coil 55, a 20 uH antenna was used for each set. Furthermore, as the electromagnetic shielding layer 57, a nanocrystalline layer of 1 mm thickness was used for each set.
[0119] The diagram shown in Fig. 8 demonstrates the power transmission efficiency depending on the load current of the receiving antenna coil. The materials and layer thicknesses (in [mm] ) tested for the outer stiffening layer 53, the inner stiffening layer 60 and the heat dissipation layer 59 are shown in Table 1 below:
[0120] As the test results shown in Fig. 8 reveal, applying stainless steel as material for any of the stiffening layers 53, 60 considerably lowers charging efficiency. In particular, stainless steel (as well as aluminum alloy) may attract additional current from the transmitter, resulting in extra power loss from the power path between the transmitter and the receiver, and result in additional un-wanted heat generation. Furthermore, according to the test results, the thicker the graphite layer of the heat dissipation layer 59 is, the better the charging efficiency is. Graphite reduces the re-sistance of the receiver, and thus improves the transmission efficiency.
[0121] The electromagnetic shielding layer 57 may comprise nanocrystalline material or FeCo50 (or a combination thereof) . These materials help to concentrate the magnetic field generated dur-ing wireless power transmission. In particular, as outlined above, during use, the flexible cover 13 is wrapped around the case body 31. In general, the case body 31 is made of aluminum alloy. Such a material significantly decreases the charging efficiency. Therefore, the electromagnetic shielding layer 57 is provided underneath the antenna coil 55, i.e. between the case body 31 and the antenna coil 55. The electromagnetic shielding layer 57 extends at least over an area such as to cover the portion of the case body 31 that is exposed to the antenna coil 55. Preferably, the electromagnetic shielding layer 57 extends at least over an area such as to cover the entire por-tion of the case body 31 that may be exposed to a wireless charging transmitter.
[0122] As shown in Figs. 2, 3 and 4, the attachment portion 19 of the flexible cover 13 comprises a plurality of attachment means 21, 23 and 25. In the embodiment depicted in these figures, the attachment portion 19 comprises three attachment means 21, 23 and 25. However, the present invention is not limited to this number of attachment means.
[0123] As shown in Fig. 4, the attachment means 21, 23 and 25 may be supported by a second stiffening element 65. The second stiffening element 65 may be made of a plastic material, for example. Providing the second stiffening element 65 secures the relative positioning of the at-tachment means 21, 23 and 25. Furthermore, providing the second stiffening element 65 facili-tates handling for attaching and detaching the flexible cover 13 to and from the charging or holding case 31.
[0124] For each of the attachment means 21, 23 and 25, a corresponding counterpart 67, 69 and 71, respectively, is provided at the charging or holding case 31. The attachment means 21, 23 and 25 and their corresponding counterparts 67, 69 and 71 are configured such that the flexible cover 13 can be reversibly attached to the charging or holding case 31. Such a reversible attach-ment can be realized, for example, by snap-fit and press-fit structures and mechanisms, hook-and-loop fasteners, magnets or metallic structures that are susceptible to magnetic interaction. The attachment means 21, 23 and 25 do not necessarily have to equal to each other.
[0125] According to some aspects of the present invention, the attachment means 21, 23 and 25 form a self-alignment structure. The self-alignment structure prevents or discourages a user to attach the flexible cover 13 to the case body 31 in a wrong orientation. Otherwise, the wireless charging would not be possible.
[0126] Figs. 9 to 14 provide a non-exhaustive number of examples of self-alignment structures. Each of Figs. 9 to 14 shows the flexible cover 13 in a bottom view, i.e. when viewed along the thickness direction 200 of the flexible cover 13, from the side, which faces the case body 31 in a state, in which the flexible cover 13 is attached to and wrapped around the case body 31 (as shown in Fig. 1) . In each of Figs. 9 to 14, a chain line indicates a symmetry plane 300 of the flexible cover 13. The symmetry plane 300 is parallel to the thickness direction 200 of the flexible cover 13. Furthermore, in each of Figs. 9 to 14, a chain-dotted line indicates an arrangement direction 400, along which the attachment means 21, 23 and 25 are arranged. The arrangement direction 400 is perpendicular to the symmetry plane 300.
[0127] In the example depicted in Fig. 9, the attachment means 21, 23 and 25 are magnets. The direction, in which each of the magnets is polarized, is parallel to the symmetry plane 300 and parallel to the thickness direction 200 of the flexible cover 13. In other words, the magnet field lines of each of the attachment means 21, 23 and 25 extend parallel to the symmetry plane 300, perpendicular to the arrangement direction 400 and parallel to the thickness direction 200. The self-alignment structure is established by means of polarity of the attachment means 21, 23 and 25.In particular, the N-poles of two neighboring attachment means 21 and 23 among the three attachment means 21, 23 and 25, are located on the same side, when seen along the thickness direction 200. The S-pole of the one remaining attachment means 25 is located on the side, on which the N-poles of the two neighboring attachment means 21 and 23 are located. Thus, the polarity of the attachment means 21, 23 and 25 exhibits asymmetry with respect to the symmetry plane 300. The corresponding counterparts 67, 69 and 71 show a polarity such that the attach-ment means 21, 23 and 25 are attracted, when the flexible cover 13 is attached to the case body 31 in a correct orientation. Hence, if a user tries to wrongly engage the flexible cover 13, the flexible cover 13 cannot be pushed towards the case body 31 such as to be attached to the case body 31 in a wrong orientation.
[0128] In the example depicted in Fig. 10, the attachment means 21, 23 and 25 are magnets. The direction, in which each of the magnets is polarized, is parallel to the arrangement direction 400, and perpendicular to the symmetry plane 300. Hence, the magnet field lines of each of the at-tachment means 21, 23 and 25 extend parallel to the arrangement direction 400 and perpendic-ular to the symmetry plane 300. The self-alignment structure is established by means of polarity of the attachment means 21, 23 and 25. In particular, the magnet field lines of two neighboring attachment means 21 and 23 among the three attachment means 21, 23 and 25, are shown in the same direction, when seen along the arrangement direction 400. For example, in Fig. 10, the magnet field lines of the neighboring attachment means 21 and 23 are directed to the right side. The magnet field line of the one remaining attachment means 25 shows to the opposite side, i.e. to the left side in Fig. 10. Thus, the polarity of the attachment means 21, 23 and 25 exhibits asymmetry with respect to the symmetry plane 300. The corresponding counterparts 67, 69 and 71 show a polarity such that the attachment means 21, 23 and 25 are attracted, when the flexible cover 13 is attached to the case body 31 in a correct orientation. Hence, if a user tries to wrongly engage the flexible cover 13, the flexible cover 13 cannot be pushed towards the case body 31 such as to be attached to the case body 31 in a wrong orientation.
[0129] In the example depicted in Fig. 11, the attachment means 21, 23 and 25 each comprise a snap-fit structure that is configured such as to be engageable in the corresponding counterpart 67, 69 and 71, respectively. The attachment means 21, 23 and 25 shown in Fig. 11 have the same size, but are arranged along the arrangement direction 400 in an asymmetric manner with respect to the symmetry plane 300. In the example shown in Fig. 11, the attachment means 21 and 25 located on the outer sides, when seen along the arrangement direction 400, have the same distance with respect to the right and left edges, respectively, of the flexible cover 13. In addition, the attachment means 23, which is located in between, is located closer to the attach-ment means 25 on the left side than to the attachment means 21 on the right side. Hence, the positioning of the attachment means 21, 23 and 25 exhibits asymmetry with respect to the sym-metry plane 300. The counterparts 67, 69 and 71 are correspondingly positioned at the case body 31.Hence, the flexible cover 13 can only be attached to the case body 31, when the flexible cover 13 is correctly orientated with respect to the case body 31.
[0130] Similar to Fig. 11, the example depicted in Fig. 12 establishes the self-alignment structure via an asymmetric positioning of the attachment means 21, 23 and 25 with respect to the sym-metry plane 300. In this example, the attachment means 23, which is located between the attach-ment means 21 and 25 on the right and left sides, respectively, is symmetrically located with respect to the symmetry plane 300. However, the attachment means 21 on the right side is more distanced from the right edge of the flexible cover 13 thanthe attachment means 25 on the left side is distanced from the left edge of the flexible cover 13. Hence, the positioning of the attach-ment means 21, 23 and 25 exhibits asymmetry with respect to the symmetry plane 300. The counterparts 67, 69 and 71 are correspondingly positioned at the case body 31. Hence, the flex-ible cover 13 can only be attached to the case body 31, when the flexible cover 13 is correctly orientated with respect to the case body 31.
[0131] In the example depicted in Fig. 13, the self-alignment structure is established via dimen-sioning and positioning of the attachment means 21, 23 and 25. As shown in Fig. 13, when meas-ured along the arrangement direction 400, a length 230 of the attachment means 23 in the middle is shorter than a length 210 of the attachment means 21, which is located on the right side. Fur-thermore, the length 230 is shorter than a length 250 of the attachment means 25, which is located on the left side. In addition, the position of the attachment means 23, which is located between the attachment means 21 and 25, is asymmetrically positioned with respect to the symmetry plane 300. The counterparts 67, 69 and 71 are correspondingly dimensioned and positioned at the case body 31. Hence, the flexible cover 13 can only be attached to the case body 31, when the flexible cover 13 is correctly orientated with respect to the case body 31.
[0132] In the example depicted in Fig. 14, the self-alignment structure is established via dimen-sioning of the attachment means 21, 23 and 25. As shown in Fig. 14, when measured along the arrangement direction 400, the length 230 of the attachment means 23 in the middle is longer than the length 250 of the attachment means 25, which is located on the left side. Furthermore, the length 250 is longer than the length 210 of the attachment means 21, which is located on the right side. The counterparts 67, 69 and 71 are correspondingly dimensioned and positioned at the case body 31. Hence, the flexible cover 13 can only be attached to the case body 31, when the flexible cover 13 is correctly orientated with respect to the case body 31.
[0133] Apart from the examples depicted in Figs. 9 to 14 and described above, it may also be possible to establish the attachment means 21, 23 and 25 by means of snap-fit elements. Fur-thermore, the type of attachment means does not have to be necessarily the same for all attach-ment means 21, 23 and 25. For example, one of the attachment means may comprise a magnet, and the remaining attachment means may be formed by snap-fit elements, hook-and-loop fasten-ers, or other reversible attachment mechanisms. In addition, it may also be possible to combine the above described self-alignment structures. That is, the self-alignment structure may be estab-lished by any combination of dimensioning, shaping, positioning or polarization of the attachment means.
[0134] As further depicted in Figs. 3 and 4, the flexible cover 13 is provided with an electric interface 73.The electric interface 73 may comprise pogo pins that are attached to the second stiffening element 65. The electric interface 73 can be electrically connected to the antenna coil 55, for example, by means of a flexible printed board 75. The flexible printed board 75 may be integrated in the flexible wrap 15. The antenna coil 55 can itself be part of the flexible printed circuit board 75.
[0135] The charging or holding case 11 may further be provided with a wireless charging circuitry (not shown in the figures) . The wireless charging circuitry may be provided with a rectifying circuit to convert AC power to DC power. The wireless charging circuitry may further be provided with a communication module for communicating with a wireless charging transmitter.
[0136] The case body 31 is provided with a case-side electric interface (not shown in the figures) . When the flexible cover 13 is attached to the case body 31, the electric interface 73 electrically connects to the case-side electric interface.
[0137] In combination with a suitable wireless charging station, the antenna coil 55 may charge the charging or holding case battery 35. For example, the antenna coil 55 receives an AC wireless signal from a wireless charging transmitter. The received AC power is converted by the rectifying circuit of the wireless charging circuitry into DC power. The converted DC power is transmitted via the electric interface 73 to a battery charger IC for charging the charging or holding case battery 35.
[0138] The charging or holding case battery 35 powers a master control unit (MCU) . The charging or holding case battery 35 may also power other modules, like a heating module.
[0139] The MCU may check an electric connection between the electric interface 73 and the case-side electric interface. For example, the wireless charging circuitry may be an IC, which addition-ally includes communication circuitry for reporting a wireless charging activity to the MCU.
[0140] When the display 54 is provided, the MCU may instruct the display 54 to provide information concerning the charging status. The MCU may instruct the display 54 to show a capacity level of the charging or holding case battery 35, a way of charging or a charging progression (or any combination thereof) . For example, under normal conditions, in case of a wireless charging event, the MCU instructs the display 54 to show information indicating that wireless charging is on.
[0141] In case the antenna coil 55 and the wireless charging transmitter are not properly aligned, the receiving IC may have a low pin signal indicating that the communication is not successful. That is, before power transmission, a wireless power transmitter sends a pin signal for checking whether there is any wireless charging receiver. In case of a low pin signal, the MCU may instruct the display 54 to show information indicating that wireless charging is on but that wireless charg-ing is not successful. For example, the information shown may indicate that the charging area 61 is not properly positioned.
[0142] The MCU may sample the temperature of the antenna coil 55. Additionally or alternatively, the MCU may sample the temperature of the flexible cover 13. The temperature (s) may be de-tected by a thermistor. The thermistor may be provided to the flexible cover 13, and may be elec-trically connected to the flexible printed board 75. The output of the thermistor may be converted by an analog-to-digital converter. By means of the sampled temperature, the MCU may control the charging current. for example, in case the temperature of the flexible cover 13 gets too high, the MCU may send a command to the battery charger IC to lower the charging current and vice versa. The MCU may also sample the charging current and voltage of the charging or holding case battery 35 for monitoring the status of the charging or holding case battery 35.
[0143] For example, at the time a user just finished using the aerosol-generating device 3, the device 3 may still be at high temperature. If the user recharges the device 3 in this state, the charging process will generate even more heat energy. Thus, the aerosol-generating device 3 or the charging or holding case 11 may overheat, thereby forming a risk for user safety, battery life, life cycle time, etc.
[0144] Therefore, by means of the thermistor, the power delivered to the battery may be regulated. In particular, the MCU may request temperature measurements of the antenna coil 55 and / or the flexible cover 13. The analog-to-digital converter is used to convert the voltage produced by a voltage divider circuit consisting of the thermistor and another resistor into a digital value that can be processed by the MCU to determine the temperature. If the temperature inside the flexible cover 13 is larger than a threshold value (for example, 60℃) , the MCU will issue a command to the charger IC to lower the charging current. If the temperature inside the flexible cover is below the threshold value, the MCU will issue a command to the charger IC to increase the charging current. Thereby, the normal working temperature may be set in a range between 0℃ –60℃.
Claims
1.A flexible cover for a charging or holding case of an aerosol generating device, the cover comprising:an attachment portion for removably attaching the cover to the charging or holding case; anda rigid portion comprising a stack of layers,wherein the stack of layers includes an antenna coil for wirelessly receiving power for wireless charging of the charging or holding case, a heat dissipation layer, and an electromagnetic shielding layer.2.The cover according to claim 1, wherein the heat dissipation layer comprises at least one of the following features:a. the heat dissipation layer comprises a metal, preferably aluminum, copper, silver, and / or gold;b. the heat dissipation layer comprises graphite;c. the heat dissipation layer consists of graphite;d. a layer thickness of the heat dissipation layer ranges from 0.1 mm to 0.8 mm, preferably is 0.5mm.3.The cover according to any of the preceding claims, wherein the electromagnetic shield-ing layer comprises at least one of the following features:a. the electromagnetic shielding layer comprises a nanocrystalline material, and / or comprises FeCo50 alloy;b. a layer thickness of the electromagnetic shielding layer ranges from 0.01 mm to 1 mm.4.The cover according to any of the preceding claims, wherein the stack of layers further includes a stiffening layer that comprises at least one of the following features:a. the stiffening layer comprises a metal and / or plastic material;b. the stiffening layer comprises polycarbonate (PC) , aluminum alloy, and / or stain-less steel;c. a layer thickness of the stiffening layer ranges from 0.1 mm to 0.5 mm, preferably from 0.3 mm to 0.4 mm.5.The cover according to any one of the preceding claims, wherein the antenna coil com-prises at least one of the following features:a. the antenna coil is glued on pressure-sensitive adhesive;b. the thickness of the antenna coil is approximately 1 mm.6.The cover according to any of the preceding claims, wherein the layers are stacked in any of the following orders, seen in a thickness direction of the cover from an outer side of the cover that is configured to be directed to the exterior in a state, in which the cover is attached to the charging or holding case:a. outer stiffening layer, antenna coil, electromagnetic shielding layer, heat dissipa-tion layer, inner stiffening layer;b. antenna coil, electromagnetic shielding layer, heat dissipation layer, stiffening layer;c. stiffening layer, antenna coil, electromagnetic shielding layer, heat dissipation layer.7.The cover according to any of the preceding claims, wherein the stack of layers further includes an electronic component that is configured to provide information to a user, wherein the electronic component comprises a display screen and / or LEDs.8.The cover according to any of the preceding claims, wherein the electronic component is arranged on top of the stack of layers, when seen in a thickness direction of the cover from an inner side of the cover, wherein the inner side of the cover is configured to be directed to the charging or holding case in a state, in which the cover is attached to the charging or holding case.9.The cover according to any of the preceding claims, comprising a flexible wrap config-ured to be reversibly wrapped around at least a portion of the charging or holding case, wherein the stack of layers is fixed to, preferably partially embedded in, particularly pref-erably entirely embedded in the flexible wrap.10.The cover according to claim 9, wherein the flexible wrap comprises at least one of the following features:a. an inner layer configured to face the charging or holding case in a state, in which the cover is attached to the charging or holding case;b. an outer layer configured to be exposed to an outer side of the cover in a state, in which the cover is attached to the charging or holding case;c. a fabric, leather and / or polyurethane (PU) material;d. a layer thickness of the inner and / or outer layer ranges from 0.5 mm to 0.8 mm;e. the stack of layers is sandwiched between the inner and outer layers;f. any of the antenna coil, the heat dissipation layer, the electromagnetic shielding layer and the stiffening layer is merged with any of the inner and outer layers;g. any of the inner and outer layers is semitransparent, porous and / or reflective, so that an underlying display screen and / or LEDs can shine through.11.The cover according to any of the preceding claims, wherein the attachment portion comprises a self-alignment structure that is configured to prevent a misalignment be-tween the cover and the charging or holding case.12.The cover according to claim 11, wherein the self-alignment structure comprises at least one attachment means, being a magnet, a metallic structure susceptible to magnetic in-teraction, a snap-fit structure, and / or a press-fit structure.13.A charging or holding case for an aerosol generating device, the charging or holding case comprising a cover according to any of the preceding claims.14.A method for wireless charging of a charging or holding case for an aerosol-generating device, the method comprising:a. attaching a cover to the charging or holding case, the cover being a cover ac-cording to any of claims 1 to 12;b. wirelessly transmitting power to the antenna coil of the cover.15.Use of the cover according to any of claims 1 to 12 for wireless charging of the charging or holding case.