Display device for aerosol generating device

Abstract

A display device for an aerosol generating device is disclosed. The display device includes a notification window and a nanophotonic material extending over a front surface of the window. In one aspect, the nanophotonic material is configured to generate and emit light therefrom comprising at least one predetermined wavelength in response to backlighting the window and light waves incident on the nanophotonic material. In another aspect, the nanophotonic material is configured to increase the amplitude of the at least one predetermined wavelength in response to backlighting the window and light waves incident on the nanophotonic material comprising at least one predetermined wavelength, and to emit light waves therefrom comprising the increased amplitude of the at least one predetermined wavelength.

Description

[Technical Field]

[0001] The present disclosure relates to a display device for an aerosol generating device, and to an aerosol generating device incorporating such a display device. [Background technology]

[0002] Known display devices for aerosol-generating devices illuminate a window of the display by using a light source within the aerosol-generating device to backlight the window with light waves generated by the light source. It is also known to impart different colors to a window illuminated by a light source to indicate the status of the device to a user. For example, it is known to impart one or more desired colors to a backlit window by using a light source that emits light at one or more specific wavelengths corresponding to the one or more desired colors. However, known display devices have a problem in that the window material can impart undesirable changes to the color of the light from the light source as it passes through the window. This can be particularly problematic when using dead-front display devices because the window of a dead-front display attenuates light of certain wavelengths. Such attenuation is commonly used to ensure that the color of the window corresponds to the color of the aerosol-generating device of which the display is a part when the display is in an inoperative state. However, when the window is backlit by a light source within the aerosol-generating device, this attenuation characteristic can impart an undesirable color to the illuminated window.

[0003] Therefore, there is a need for a display device that provides improved color control. Summary of the Invention

[0004] As used herein, the term "light" refers to emissions of electromagnetic radiation within the visible range of the electromagnetic spectrum, generally understood to encompass wavelengths ranging from about 380 nm to about 740 nm. White light is formed from a broad spectrum of light of different wavelengths, each wavelength corresponding to a different color.

[0005] As used herein, the term "nanostructure" refers to a structural entity whose major dimension is less than 999 nm. The terms "nanovoid" and "nanoparticle" described below should be interpreted accordingly.

[0006] As used herein, the term "quantum dot" refers to a semiconductor nanoparticle that constrains charge carriers in three dimensions.

[0007] According to a first aspect of the present invention, there is provided a display device for an aerosol generating device, the display device comprising:

[0008] Notification window and

[0009] a nanophotonic material extending over the front surface of the window;

[0010] The nanophotonic material is configured to generate and emit light therefrom comprising at least one predetermined wavelength in response to light waves that backlight the window and are incident on the nanophotonic material.

[0011] The nanophotonic material responds to incident light waves such that the incident light waves trigger or energize the nanophotonic material to generate and emit light comprising at least one desired predetermined wavelength. Because the predetermined wavelengths correspond to colors associated with within the visible portion of the electromagnetic spectrum, the use of nanophotonic materials extending across the front surface of a window provides an improved ability to adjust the color of a display window when backlit and to compensate for any attenuation of the wavelength component(s) of the incident light waves caused by the underlying window material.

[0012] Preferably, the nanophotonic material comprises a plurality of nanostructures, the nanostructures comprising either or a combination of nanocavities and nanoparticles, arranged, sized, or formed to generate and emit light therefrom comprising at least one predetermined wavelength in response to light waves backlighting the window and incident on the nanophotonic material.

[0013] Silicon-based materials and gallium nitride (GaN) are examples of suitable materials for use in forming nanophotonic materials. For example, the nanophotonic material can include a substrate of silicon-based materials or gallium nitride (GaN), and nanoparticles can be disposed within the substrate. Metal oxides and indium gallium nitride (InGaN) are examples of suitable materials for nanoparticles. However, these particular materials are provided by way of example only. The nanoparticles can conveniently take the form of quantum dots, for example, an arrangement of quantum dots can be provided within the substrate of the nanophotonic material.

[0014] Photolithography can be used to form nanophotonic materials. As an example, if a nanophotonic material contains both nanocavities and nanoparticles, a substrate material containing a certain arrangement of nanoparticles can be used as the starting material. Alternatively, nanoparticles may not be present in the substrate starting material. In either case, photolithography can be used to etch a predetermined arrangement of nanocavities into the substrate starting material.

[0015] Preferably, the nanostructures are positioned, sized or shaped such that their generation and emission of light comprising at least one predetermined wavelength is conditional on a parameter of the incident light wave having a predetermined value or range of values. This conditionality facilitates improved control over under what circumstances the display device will emit a particular wavelength (and thereby color), i.e., at least one predetermined wavelength with its corresponding color(s). The parameter is conveniently selected from one or more of the wavelength, frequency and amplitude of the incident light wave.

[0016] Advantageously, the nanostructure may include nanoparticles arranged, sized, or shaped within the nanophotonic material such that individual nanoparticles or groups of nanoparticles can be driven by an incident light wave to enter into plasmon resonance and generate and emit light comprising at least one predetermined wavelength. In this preferred embodiment, the incident light wave serves to energize the nanophotonic material to induce plasmon resonance in the individual nanoparticles or groups of nanoparticles, resulting in nanoparticles that emit light at one or more desired wavelengths, i.e., at least one predetermined wavelength. The wavelengths of light emitted by the nanoparticles or groups of nanoparticles via plasmon resonance can be determined (e.g., computationally) for a given configuration of the nanophotonic material.

[0017] Advantageously, the plurality of nanostructures includes a first group of nanostructures and a second group of nanostructures, the first group configured to generate and emit light therefrom having a first wavelength composition, the first wavelength composition comprising at least one first predetermined wavelength, and the second group configured to generate and emit light therefrom having a second wavelength composition, the second wavelength composition comprising at least one second predetermined wavelength, the first and second wavelength compositions being different from one another. The configuration of the nanostructures in the first and second groups to provide light having different wavelength compositions improves control over the wavelength and color of light generated and emitted by different portions of the nanophotonic material. The first wavelength composition can consist of a single wavelength, and the same can apply to the second wavelength composition. Alternatively, the first wavelength composition can consist of two or more wavelengths, and again, the same can apply to the second wavelength composition.

[0018] Preferably, the first group of nanostructures comprises a first plurality of nanoparticles sized and arranged within the nanophotonic material to plasmon resonate in response to incident light waves to generate and emit light therefrom having a first wavelength composition. Similarly, the second group of nanostructures may comprise a second plurality of nanoparticles sized and arranged within the nanophotonic material to plasmon resonate in response to incident light waves to generate and emit light therefrom having a second wavelength composition.

[0019] Conveniently, the first and second groups of nanostructures are arranged, sized, or formed such that generation and emission of light having a first wavelength composition according to the first group is conditioned on a parameter of an incident light wave having a first predetermined value or range of values, and generation and emission of light having a second wavelength composition according to the second group is conditioned on a parameter of the incident light wave having a second predetermined value or range of values, the first and second predetermined values ​​and ranges of values ​​being different from one another. This feature provides improved control over the wavelength and color of light emitted by different portions of the nanophotonic material. The display device may further comprise a light source in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material, the light source operable to switch between a parameter of the incident light wave having a first predetermined value or range of values ​​and a parameter of the incident light wave having a second predetermined value or range of values. Conveniently, the parameter is selected from one or more of the wavelength, frequency, and amplitude of the incident light wave. It is therefore found that variations in the incident light waves generated by a light source can be used to control the wavelength and corresponding color of light generated and emitted by a nanophotonic material.

[0020] In the various forms of nanophotonic materials described above, the nanophotonic material may include a crystalline lattice defining a network of nanocavities, with individual nanoparticles or groups of nanoparticles contained within one or more regions defined within the crystalline lattice between the nanocavities. Such an arrangement of individual nanoparticles or groups of nanoparticles within the crystalline lattice is particularly suitable for plasmon resonance driven by incident light waves to generate and emit light at a desired wavelength, i.e., at least one predetermined wavelength. The individual nanocavities of the lattice may be spaced apart from one another in a predetermined pattern or repeating arrangement. However, there may be discontinuities in the predetermined pattern or repeating arrangement in one or more regions within the crystalline lattice between adjacent nanocavities. Positioning individual nanoparticles or groups of nanoparticles in such discontinuous regions has been found to be particularly suitable for plasmon resonance light generation and emission, with individual nanoparticles or groups of nanoparticles located in such regions being susceptible to plasmon resonance driven by incident light waves, as described above. The wavelengths emitted by individual nanoparticles or groups of nanoparticles located in such regions can be computationally determined based on the size and location of the region, the size and location of the nanocavity, the materials from which the lattice and nanoparticles are made, and the size and location of the nanoparticles. Different groups of nanoparticles within a crystalline lattice can generate and emit light therefrom having different respective wavelength compositions in response to incident light waves. This difference in wavelength composition can be influenced by any one or more of: i) the specific regions in which the different groups of nanoparticles are located; ii) the size and number of nanoparticles in the different groups; and iii) the use of nanoparticles formed from different materials in the different groups.

[0021] Advantageously, the nanoparticles have a diameter ranging from 9 nm to 120 nm. The nanocavities may have a diameter ranging from 100 nm to 500 nm.

[0022] Preferably, the display device further comprises a light source in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material. Light-emitting diodes (LEDs) have been found to be particularly suitable as light sources and have good energy efficiency. However, other light sources capable of backlighting the window may be suitable as well. The light source is conveniently adapted to backlight the window with light waves comprising a spectrum of light with different wavelengths. Advantageously, the light source is adapted to switch between emitted light waves having different wavelength compositions. For example, in a first operating mode, the light source may be configured to emit light waves consisting of one or more wavelengths that provide the light with a red color (i.e., wavelengths generally in the range of 625-740 nm), in a second operating mode, the light source may be configured to emit light waves consisting of one or more wavelengths that provide the light with a green color (i.e., wavelengths generally in the range of 500-565 nm), and in a third operating mode, the light source may be configured to emit light waves consisting of one or more wavelengths that provide the light with a blue color (i.e., wavelengths generally in the range of 450-485 nm).

[0023] The nanophotonic material is conveniently provided as a layer of nanophotonic material extending over the front surface of the window. Preferably, the layer of nanophotonic material is provided as a layer of polymer-based film.

[0024] The display can be a dead-front display in which the window includes a material configured to attenuate light at one or more predetermined attenuation wavelengths. Preferably, the at least one predetermined wavelength is within 50 nm of at least one of the one or more predetermined attenuation wavelengths. Thus, the light generated and emitted by the nanophotonic material can be of a wavelength and color composition closely similar to the wavelength and color of light that would be attenuated by the window material of the dead-front display.

[0025] In a second aspect of the present invention, there is provided a display device for an aerosol generating device, the display device comprising:

[0026] Notification window and

[0027] a nanophotonic material extending over the front surface of the window;

[0028] The nanophotonic material is configured to backlight the window and, in response to light waves comprising at least one predetermined wavelength being incident on the nanophotonic material, increase the amplitude of the at least one predetermined wavelength and emit therefrom light waves comprising the at least one predetermined wavelength with increased amplitude.

[0029] As discussed above, the nanophotonic material preferably includes a plurality of nanostructures, the nanostructures including either or a combination of nanocavities and nanoparticles. The presence of such nanocavities or nanoparticles can have the effect of enhancing the intensity of the color associated with at least one predetermined wavelength of light. The nanostructures can be positioned, sized, or shaped to increase the amplitude of the at least one predetermined wavelength in response to backlighting the window and light waves including the at least one predetermined wavelength incident on the nanophotonic material, and emit therefrom light waves including the at least one predetermined wavelength with increased amplitude.

[0030] Advantageously, the plurality of nanostructures are arranged and sized to diffract incident light waves comprising at least one predetermined wavelength in response to light waves incident on the nanophotonic material, backlighting the window. Preferably, the plurality of nanostructures includes at least a first diffraction site and a second diffraction site, the first and second diffraction sites arranged and sized to diffract at least one predetermined wavelength of the incident light waves by a predetermined amount, such that the diffracted predetermined wavelength light from the first diffraction site and the diffracted predetermined wavelength light from the second diffraction site intersect and reinforce each other. Thus, the first and second diffraction sites can be thought of as functioning like slits in a diffraction grating. When the nanostructures include either or a combination of nanocavities and nanoparticles, each of the nanocavities and / or nanoparticles can individually function as a separate diffraction site.

[0031] Preferably, the nanophotonic material comprises a crystalline lattice defining a network of nanocavities. In such a crystalline lattice of nanocavities, the nanocavities can be arranged and sized to behave like slits in a diffraction grating in response to incident light waves, which pass through and are diffracted by individual cavities of the nanocavities. In a further preferred embodiment, individual nanoparticles or clusters of nanoparticles can be provided within the crystalline lattice between the nanocavities. Similarly, in such a crystalline lattice containing both nanoparticles and nanocavities, the nanoparticles and nanocavities can be arranged and sized to behave individually like slits in a diffraction grating in response to incident light waves, diffracting the incident light waves.

[0032] As described above for the first aspect, silicon-based materials and gallium nitride (GaN) are examples of suitable materials for use in forming the nanophotonic material. For example, the nanophotonic material can include a substrate of silicon-based materials or gallium nitride (GaN), and nanoparticles can be disposed within the substrate. Metal oxides and indium gallium nitride (InGaN) are examples of suitable materials for the nanoparticles. However, these particular materials are provided by way of example only. The nanoparticles can conveniently take the form of quantum dots, for example, an arrangement of quantum dots can be provided within the substrate of the nanophotonic material.

[0033] As described above for the first embodiment, photolithography can be used to form nanophotonic materials. As an example, if the nanophotonic material contains both nanocavities and nanoparticles, a substrate material containing a certain arrangement of nanoparticles can be used as the starting material. Alternatively, nanoparticles may not be present in the substrate starting material. In either case, photolithography can be used to etch a predetermined arrangement of nanocavities into the substrate starting material.

[0034] As described above for the first embodiment, the nanoparticles preferably have a diameter in the range of 9 nm to 120 nm, and the nanocavities preferably have a diameter in the range of 100 nm to 500 nm.

[0035] The display device may further comprise a light source in optical communication with the window for generating light waves to backlight the window, the light waves comprising at least one predetermined wavelength. As described above for the first aspect, light emitting diodes (LEDs) have been found to be particularly suitable as light sources and to have good energy efficiency. However, other light sources capable of backlighting the window may be suitable as well.

[0036] Preferably, the display is a dead-front display in which the window comprises a material configured to attenuate light at one or more predetermined attenuation wavelengths, at least one predetermined wavelength being within 50 nm of the one or more predetermined attenuation wavelengths. Thus, the nanophotonic material can compensate for the attenuation of the amplitude of the predetermined wavelengths by the window material by acting to increase the intensity of the predetermined wavelengths. This behavior can be useful for at least partially compensating for or offsetting the attenuation effect of the dead-front display on light of specific wavelengths during operation of the display.

[0037] As described above for the first aspect, the nanophotonic material is conveniently provided as a layer of nanophotonic material extending over the front surface of the window. Preferably, the layer of nanophotonic material is provided as a layer of polymer-based film.

[0038] In a third aspect, a display device for an aerosol generating device may be provided, the display device comprising a notification window and a nanophotonic material extending over a front surface of the window, the nanophotonic material being configured according to both the first and second aspects described above.

[0039] Advantageously, there is provided an aerosol generating device comprising a display device as outlined in any of the preceding paragraphs in relation to the first three aspects, the aerosol generating device further comprising: a housing, wherein the display device is integrated within the housing; and a light source enclosed within the housing and in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material. Preferably, the window is a notification window, the color of which (visible to a user of the aerosol generating device) is responsive to the light source backlighting the window to notify the user of the status of the device. The color of the notification window may indicate whether the aerosol generating device (or a component part thereof) has reached or exceeded its designed operating temperature. For example, a blue color on the backlit window may indicate that a heating element of the aerosol generating device has not yet reached its designed operating temperature, a green color on the backlit window may indicate that the heating element has reached its designed operating temperature, and a red color may indicate that the heating element has exceeded its designed operating temperature. Of course, in other embodiments, there may be different associations between predetermined colors of the backlit notification window and predetermined states of the aerosol generating device.

[0040] Conveniently, the aerosol-generating device is a smoking article for generating an aerosol for inhalation by a user. Alternatively, the aerosol-generating device is configured to cooperate with a smoking article to guide the smoking article to generate an aerosol for inhalation by a user. The aerosol-generating device is preferably sized in an elongated form so as to be suitable for being held between a user's thumb and fingers. The aerosol-generating device is preferably cylindrical in cross section. Conveniently, the housing of the device is adapted to contain the aerosol-forming substrate. A power source and a heating element are also preferably contained within the housing of the device, the power source being configured to provide power to the heating element so that the heating element can apply heat to the aerosol-forming substrate to generate vapor from the substrate. This same power source preferably also provides power to any light source provided within the device used to backlight the display window. The aerosol-forming substrate may conveniently be provided as part of a replaceable cartridge. Preferably, the aerosol-forming substrate is provided in solid form, although the aerosol-forming substrate may alternatively be provided in liquid form. The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise a plant-derived material. The aerosol-forming substrate may comprise tobacco. The aerosol-forming substrate may comprise a homogenized tobacco material. The aerosol-forming substrate may comprise a non-tobacco-containing material. The aerosol-forming substrate may comprise a homogenized plant-derived material. [Example]

[0041] The present invention is defined in the claims. However, the following provides 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.

[0042] Example 1: A display device for an aerosol generating device, comprising: a notification window; and a nanophotonic material extending over a front surface of the window, the nanophotonic material configured to backlight the window and generate and emit light therefrom comprising at least one predetermined wavelength in response to light waves incident on the nanophotonic material. Example 2: 10. The display device of Example 1, wherein the nanophotonic material comprises a plurality of nanostructures, the nanostructures comprising one or a combination of nanocavities and nanoparticles, and the nanostructures are positioned, sized, or shaped to generate and emit light therefrom comprising at least one predetermined wavelength in response to light waves backlighting the window and incident on the nanophotonic material. Example 3: 3. The display device of example 2, wherein the nanostructures are positioned, sized, or formed such that generation and emission therefrom of light comprising at least one predetermined wavelength is conditioned on a parameter of the incident light wave having a predetermined value or range of values. Example 4: 4. The display device of example 3, wherein the parameter is selected from one or more of a wavelength, a frequency, and an amplitude of the incident light wave. Example 5: A display device described in any one of Examples 2 to 4, wherein the nanostructure includes nanoparticles arranged, sized, or formed within the nanophotonic material such that individual nanoparticles or groups of nanoparticles are drivable by incident light waves and undergo plasmon resonance to generate and emit light comprising at least one predetermined wavelength. Example 6: A display device as described in any one of Examples 2 to 5, wherein the plurality of nanostructures includes a first group of nanostructures and a second group of nanostructures, the first group configured to generate and emit light therefrom having a first wavelength composition, the first wavelength composition including at least one first predetermined wavelength, and the second group configured to generate and emit light therefrom having a second wavelength composition, the second wavelength composition including at least one second predetermined wavelength, and the first and second wavelength compositions are different from each other. Example 7: A display device as described in Example 6, wherein the first and second groups of nanostructures are arranged, sized, or formed such that the generation and emission of light having a first wavelength composition according to the first group is conditioned on a parameter of an incident light wave having a first predetermined value or range of values, and the generation and emission of light having a second wavelength composition according to the second group is conditioned on a parameter of an incident light wave having a second predetermined value or range of values, and the first and second predetermined values ​​and ranges of values ​​are different from each other. Example 8: 8. The display device of Example 7, further comprising a light source in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material, the light source operable to switch between a parameter of the incident light wave having a first predetermined value or range of values ​​and a parameter of the incident light wave having a second predetermined value or range of values. Example 9: 9. The display device of any of Examples 7 or 8, wherein the parameter is selected from one or more of the wavelength, frequency, and amplitude of the incident light wave. Example 10: A display device described in any one of Examples 2 to 9, wherein the nanophotonic material is composed of a crystalline lattice defining a network of nanocavities, and individual nanoparticles or groups of nanoparticles are contained within one or more regions defined within the crystalline lattice between the nanocavities. Example 11: 11. The display device according to any one of Examples 2 to 10, wherein the nanoparticles have a diameter in the range of 9 nm to 120 nm. Example 12: 12. The display device according to any one of Examples 2 to 11, wherein the nanocavities have diameters in the range of 100 nm to 500 nm. Example 13: 13. The display of any one of examples 1-12, wherein the display further comprises a light source in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material. Example 14: 14. The display device of any one of Examples 1 to 13, wherein the display device is a dead-front display device, wherein the window comprises a material configured to attenuate light at one or more predetermined attenuation wavelengths. Example 15: 15. The display device of example 14, wherein the at least one predetermined wavelength is within 50 nm of at least one of the one or more predetermined attenuation wavelengths. Example 16: A display device for an aerosol generating device, the display device comprising: a notification window; and a nanophotonic material extending over a front surface of the window, the nanophotonic material configured to backlight the window and, in response to light waves comprising at least one predetermined wavelength being incident on the nanophotonic material, increase the amplitude of the at least one predetermined wavelength and emit light waves comprising the at least one predetermined wavelength with increased amplitude therefrom. Example 17: 17. The display device of Example 16, wherein the nanophotonic material comprises a plurality of nanostructures, the nanostructures comprising either or a combination of nanocavities and nanoparticles, and the nanostructures are arranged, sized or formed to increase the amplitude of at least one predetermined wavelength in response to light waves incident on the nanophotonic material by backlighting the window, and to emit light waves therefrom comprising the at least one predetermined wavelength with increased amplitude. Example 18: 18. The display device of Example 17, wherein the plurality of nanostructures are arranged and sized to diffract incident light waves in response to light waves comprising at least one predetermined wavelength being incident on the nanophotonic material by backlighting the window. Example 19: 19. The display device of Example 18, wherein the plurality of nanostructures include at least a first diffraction region and a second diffraction region, the first and second diffraction regions being arranged and sized to diffract at least one predetermined wavelength of an incident light wave by a predetermined amount, such that the diffracted predetermined wavelength light from the first diffraction region and the diffracted predetermined wavelength light from the second diffraction region intersect and reinforce each other. Example 20: 20. The display device of any one of Examples 17 to 19, wherein the nanophotonic material comprises a crystalline lattice defining a network of nanocavities. Example 21: 21. The display device of example 20, wherein individual nanoparticles or clusters of nanoparticles are provided within the crystal lattice between nanocavities. Example 22: 22. The display device according to any one of Examples 17 to 21, wherein the nanoparticles have a diameter in the range of 9 nm to 120 nm. Example 23: 23. The display device according to any one of Examples 17 to 22, wherein the nanocavities have diameters in the range of 100 nm to 500 nm. Example 24: 24. The display device of any one of Examples 16 to 23, wherein the display device further comprises a light source in optical communication with the window for generating light waves to backlight the window, the light waves comprising at least one predetermined wavelength. Example 25: A display device described in any one of Examples 16 to 24, wherein the display device is a dead-front display device, the window comprising a material configured to attenuate light at one or more predetermined attenuation wavelengths, and at least one predetermined wavelength is within 50 nm of the one or more predetermined attenuation wavelengths. Example 26: 26. The display device of any one of examples 1 to 25, wherein the nanophotonic material is provided as a layer of nanophotonic material extending over the front surface of the window. Example 27: An aerosol generating device comprising a display device described in any one of Examples 1 to 26, further comprising: a housing, wherein the display device is integrated within the housing; and a light source enclosed within the housing and in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material. Example 28: 28. The aerosol generation device of Example 27, further comprising a heating element configured to apply heat to an aerosol-forming substrate located within the aerosol generation device. Example 29: An aerosol generating device described in either Example 27 or Example 28, wherein the window is a notification window whose color responds to a light source that backlights the window with light waves to notify the user of the status of the device. Example 30: 30. The aerosol-generating device according to any one of Examples 27 to 29, wherein the aerosol-generating device is a smoking article for generating an aerosol for inhalation by a user. Example 31: An aerosol generating device described in any one of Examples 27 to 29, wherein the aerosol generating device is configured to cooperate with a smoking article to guide the smoking article to generate an aerosol for inhalation by a user.

[0043] The embodiment will now be further described with reference to the figures. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 shows a schematic diagram of an aerosol generating device provided with a display device. [Figure 2] FIG. 2 shows a cross-sectional view of the aerosol generating device of FIG. 1 taken along line AA in FIG. 1 (including a detailed view of the display device). [Figure 3] FIG. 3 shows a cross-sectional schematic view of a first embodiment of a display device for use with the aerosol generating device of FIG. [Figure 4] FIG. 4 shows a cross-sectional schematic view of a second embodiment of a display device for use with the aerosol generating device of FIG. [Figure 5] FIG. 5 shows a cross-sectional schematic view of a third embodiment of a display device for use with the aerosol generating device of FIG. [Figure 6] FIG. 6 shows a cross-sectional schematic view of a fourth embodiment of a display device for use with the aerosol generating device of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0045] FIG. 1 illustrates an aerosol generating device 1. The aerosol generating device 1 is elongated and generally cylindrical in cross section. The housing 2 has an upper portion 2a and a lower portion 2b. The housing parts 2a and 2b mate with each other at a diagonal interface 3. A display device 4 is integrated into the housing 2. The display device includes four notification windows 51, 52, 53, and 54. The notification windows 51, 52, 53, and 54 define icons of different shapes. The aerosol generating device 1 is sized to a length and diameter suitable for being held between a user's thumb and fingers. The aerosol generating device 1 illustrated in FIG. 1 is a smoking article for generating smoke for inhalation by a user. Although not shown, a replaceable cartridge containing an aerosol-forming substrate and an electrically powered heating element are enclosed within the housing 2 of the device 1, and the heating element is operable to apply heat to the aerosol-forming substrate to generate an inhalable aerosol therefrom for inhalation through an opening in the upper portion 2a of the housing 2 of the device 1. This inhalable aerosol is represented by the array of dashed lines in FIG.

[0046] FIG. 2 shows a cross-sectional view of the aerosol generating device 1 taken along line AA in FIG. 1 , corresponding to the location of the notification window 51 at the bottom of the display device 4. An accompanying detailed view of the notification window 51 is also provided in FIG. 2 . The light source 61 is located within a cavity 71 provided within the housing 2. For the illustrated embodiment, the light source 61 is a light-emitting diode (LED). The light source 61 is mounted on a printed circuit board 8 that includes wiring and control circuitry (not shown) for controlling the operation of the light source. The printed circuit board 8 is electrically coupled to a power source 9 for providing power to the light source 61. The power source 9 not only provides power to the printed circuit board 8, the light source 61, and other components mounted on the printed circuit board, but also to a heating element (also not shown) used to apply heat to the aerosol-forming substrate (not shown). For the embodiment shown in FIG. 2 , the power source 9 is a rechargeable battery. The cavity 71 is positioned such that the light source 61 is in optical communication with the back surface 511 of the notification window 51. In use, light source 61 illuminates the back surface 511 of notification window 51 with light waves, thereby backlighting the window for viewing by a user of device 1. Cavity 71 is positioned such that light waves from light source 61 backlight window 51 without illuminating any of the other three notification windows 52, 53, 54 of display device 4. Printed circuit board 8 extends the length of display device 4. Three additional light sources (not shown) are mounted on printed circuit board 8 and positioned within respective cavities (also not shown) for backlighting each of the remaining three notification windows 52, 53, 54. The configuration of light source 61 and notification window 51 is indicative of the configuration of notification windows 52, 53, 54 and their own respective light sources.

[0047] For aerosol generating device 1, display 4 is a dead-front display, and each of windows 51, 52, 53, 54 appears colored when viewed from outside the device to correspond to a color on housing 2 when its respective light source (e.g., light source 61 of window 51) is inoperative. Window 51 is fabricated from a polymer configured to attenuate light at one or more predetermined attenuation wavelengths, thereby imparting a tint to window 51. A layer of nanophotonic material 56 overlies front surface 512 of window 51 (see FIG. 2).

[0048] FIG. 3 shows a schematic diagram of a first embodiment of a layer of nanophotonic material 56 overlying the front surface 512 of the window 51. The layer of nanophotonic material 56 is provided as a layer of polymer-based film. The layer of nanophotonic material 56 is formed from a crystalline lattice of gallium nitride (GaN) that defines a network of nanocavities 561. The nanocavities 561 are spaced apart from one another in a predetermined pattern or repeating arrangement. However, the lattice is fabricated to define discontinuities in the predetermined pattern or arrangement of the nanocavities 561. These discontinuities are located in regions 562a-562f of the crystalline lattice. The discontinuities in regions 562a-562c, as well as the discontinuities in regions 562d-562f, define a triangular pattern. For the embodiment shown in FIG. 3, each of the discontinuous regions 562a-562f contains a group of nanoparticles 563 in the form of quantum dots formed from indium nitride (InGaN). As can be seen in FIG. 3, the nanophotonic material 56 was fabricated to provide clusters 564a, 564b of groups of nanoparticles 563. For the embodiment shown in FIG. 3, each cluster 564a, 564b consists of three groups of nanoparticles 563 arranged in a triangular configuration. Six groups of nanoparticles 563 (three per cluster 564a, 564b) are located in six discrete regions 562a through 562f of the crystalline grating. The nanocavities 561 are each sized to have a diameter ranging from 100 nm to 500 nm. The nanoparticles 563 are sized to have a diameter ranging from 9 nm to 120 nm.

[0049] The behavior of nanophotonic material 56 overlying the front surface 512 of notification window 51 for the embodiment of Figure 3 will be described in response to the window being backlit by light waves generated by light source 61. Light source 61 is dependent upon, and in accordance with, instructions provided by control circuitry provided on printed circuit board 8 to emit first and second incident light waves W at different times. i1 and W i2 For the embodiment shown and described in FIG. 3, the first and second incident light waves W i1 and W i2 has a distinct wavelength composition. For the illustrated embodiment, the first incident light wave W i1 is λ i1.1 ,λ i1.2… λ i1.m It consists of wavelengths of "m" components that provide a wavelength composition of 、 Second incident light wave W i2 is λ i2.1 ,λ i2.2… λ i2.n The first incident light wave W i1 The wavelength composition of the second incident light wave W i2 In an alternative embodiment, the wavelength composition of the first and second incident light waves W i1 and W i2 may alternatively each consist of a single wavelength, with the first incident light wave W i1 is the wavelength of the second incident light wave W i2 The wavelength is different from that of

[0050] A light source emits a first incident light wave W i1 When generating a light wave W i1 The light wave W first passes through the window 51 and is incident on the layer of nanophotonic material 56. i1 When incident on the nanophotonic material 56, it has the effect of driving or energizing the clusters 564a, 564b of the group of nanoparticles 563 into plasmon resonance. For the example of FIG. 3, the light wave W generated by the light source 61 i1 Wavelength composition λ i1.1 ,λ i1.2… λ i1.mis selected so as to not include any of one or more predetermined attenuation wavelengths of the window material 51. 、 3, the arrangement and size of the clusters 564a, 564b and respective nanoparticles 563 are such that each cluster 564a, 564b emits an output wavelength λ corresponding to a desired or predetermined color of light. o1 output lightwave W o1 Thus, a viewer of the window 51 of the display device 4, when backlit by the light source 61, will see that the window emits and radiates light of an output wavelength λ o1 appears to be illuminated with a color corresponding to the

[0051] A light source 61 emits a second wavelength composition λ i2.1 ,λ i2.2… λ i2.n When the control circuit of the printed circuit board 8 is switched on by an instruction provided by the control circuit of the printed circuit board 8 to generate a second light wave Wi2 having a i2 passes through window 51 and enters the layer of nanophotonic material 56. i1 With respect to the light wave W i2 also has the effect of driving or energizing clusters 564a, 564b of the group of nanoparticles 563 into plasmon resonance. Again, the light wave W generated by light source 61 i2 Wavelength composition λ i2.1 ,λ i2.2… λ i2.n is the light wave W i2 is selected to be free of one or more predetermined attenuation wavelengths of the window material 51 to ensure that the clusters 564 a, 564 b have sufficient amplitude and energy to drive the clusters 564 a, 564 b into plasmon resonance. The arrangement, size, and material of the clusters 564 a, 564 b of nanoparticles 563 are such that each cluster 564 a, 564 b outputs an output wavelength λ corresponding to a desired or predetermined color of light. o2 output lightwave W o2The output wavelength λ of the output light wave Wo2 is o2 is the output light wave W o1 Output wavelength λ o1 Therefore, the different wavelength composition (λ i1.1 ,λ i1.2… λ i1.m ), (λ i2.1 ,λ i2.2… λ i2.n ) light wave W i1 , W i2 drives the clusters 564a, 564a to produce different respective output wavelengths λ o1, λ o2 different output lightwaves W o1 , W o2 respectively. o1, λ o2 correspond to different light colors. Thus, to a person looking at the window 51 of the display device 4, 、 Wavelength composition λ i1.1 ,λ i1.2… λ i1.m A light wave W i1 When backlit by a wavelength composition λ i2.1 ,λ i2.2… λ i2.n A light wave W i2 The window appears to be illuminated with a different color compared to when it is backlit by 。 The different colors can indicate the state of the aerosol generating device at a given time. For example, o1 (generally corresponding to blue light) may indicate that the heating element of the aerosol generating device 1 has not yet reached its designed operating temperature, while an output wavelength λ of about 530 nm o2 (generally corresponding to a green light) may indicate that the heating element has reached its designed operating temperature. Of course, in other embodiments, the clusters 564a, 564b of nanoparticles 563 may be arranged, sized, or formed from materials such that they generate and emit light at output wavelengths corresponding to different colors.

[0052] FIG. 4 shows a schematic diagram of a second embodiment of a layer of nanophotonic material 56′ overlying the front surface 512 of the window 51. The layer of nanophotonic material 56′ is formed from a crystalline lattice that defines a network of nanocavities 561′. The nanocavities 561′ are spaced apart in a predetermined pattern or repeating arrangement. In common with the embodiment of FIG. 3, the lattice is fabricated to define discontinuities in the predetermined pattern or arrangement of the nanocavities 561′. These discontinuities are located in regions 562a′ through 562e′ of the crystalline lattice. The discontinuities in regions 562a′ through 562c′ define a triangle, while the discontinuities in regions 562d′ through 562e′ define a rectilinear pattern. Each of the discontinuous regions 562a′ through 562e′ contains a group of nanoparticles 563′ in the form of quantum dots. As can be seen in FIG. 4, nanophotonic material 56′ was fabricated to provide clusters 564a′, 564b′ of groups of nanoparticles 563′. For the embodiment of FIG. 4, cluster 564a′ consists of three groups of nanoparticles 563′ arranged in a triangular configuration, and cluster 564b′ consists of two groups of nanoparticles 563′ arranged in a linear configuration. Five groups of nanoparticles 563′ are located in five discrete regions 562a′ through 562e′. For the embodiment of FIG. 3, nanocavities 561′ are each sized to have a diameter ranging from 100 nm to 500 nm, and nanoparticles 563′ are sized to have a diameter ranging from 9 nm to 120 nm. However, the nanoparticles in cluster 564a′ are formed of a material of a different composition than the nanoparticles in cluster 564b′. As explained below, the use of different materials for the nanoparticles 563', 564b' of different clusters 564a' causes the nanoparticles 563' of different clusters 564a', 564b' to respond differently to two different incident light waves, the different responses depending on the difference in one or more parameters between two such incident light waves.

[0053] The behavior of nanophotonic material 56' overlying the front surface 512 of notification window 51 for the embodiment of Figure 4 will be described in response to the window being backlit by light waves generated by light source 61. Light source 61 emits first light waves W at different times depending on, and in accordance with, instructions provided by control circuitry provided on printed circuit board 8. i1’ and the second light wave W i2’ For the described embodiment, the incident light wave W i1’ and W i2’ has a distinct wavelength composition. In the illustrated embodiment, the first incident light wave W i1’ is λ i1’.1 ,λ i1’.2… λ i1’.m The second incident light wave W consists of "m" component wavelengths that provide a wavelength composition of i2’ is λ i2’.1 ,λ i2’.2… λ i2’.n Consists of "n" component wavelengths that provide a wavelength composition of 。 First incident light wave W i1’ The wavelength composition of the second incident light wave W i2’ In an alternative embodiment, the wavelength composition of the first and second incident light waves W i1’ and W i2’ may alternatively each consist of a single wavelength, with the first incident light wave W i1 is the wavelength of the second incident light wave W i2’ The wavelength is different from that of

[0054] A light source emits a first incident light wave W i1’ When generating a light wave W i1’ The light wave W first passes through window 51 and is incident on the layer of nanophotonic material 56'. i1’ When incident on nanophotonic material 56′, it drives and energizes clusters 564 a′ of nanoparticles 563 into plasmon resonance. The arrangement, size, and material of clusters 564 a′ and their respective nanoparticles 563′ are such that clusters 564 a′ emit light at an output wavelength λ corresponding to a desired or predetermined color of light. o1’ output lightwave W o1’However, the different material used for the nanoparticles 563' of cluster 564b' allows the nanoparticles 563' of cluster 564b' to emit and radiate wavelengths of composition λ i1’.1 ,λ i1’.2… λ i1’.m The first incident light wave W consists of i1’ , resulting in no or negligible plasmon resonance of nanoparticles 563′ of cluster 564b′. i1’.1 ,λ i1’.2… λ i1’.m A light wave W i1’ When the window is backlit by the cluster 564a′, the window receives light with an output wavelength λ o1’ will appear to be illuminated with a color corresponding to

[0055] A light source 61 emits a second wavelength composition λ i2’.1 ,λ i2’.2… λ i2’.n A second incident light wave Wi 2’ When the lightwave W is switched on by instructions provided on the control circuit of the printed circuit board 8 to generate i2’ passes through window 51 and enters the layer of nanophotonic material 56'. i2’ When incident on nanophotonic material 56′, it drives and energizes clusters 564b′ of nanoparticles 563′ into plasmon resonance. The arrangement and size of clusters 564b′ and their constituent nanoparticles 563′ produce an output wavelength λ corresponding to a desired or predetermined color of light. o2’ output lightwave W o2’ However, the different material used for the nanoparticles 563' of cluster 564a' results in the nanoparticles 563' of cluster 564a' generating and emitting 、 wavelength composition λ i2’.1 ,λ i2’.2… λ i2’.n The second incident light wave W consists of i2’, so that there is no or negligible plasmon resonance of the nanoparticles 563′ of cluster 564a′. Thus, a viewer of window 51 of display device 4 will not see the wavelength composition λ i2’.1 ,λ i2’.2… λ i2’.n A light wave W i2’ When the window is backlit by cluster 564b′, the window will have an output wavelength λ of light generated and emitted only by cluster 564b′. o2’ will appear to be illuminated with a color corresponding to

[0056] The embodiment of FIG. 4 allows the use of different materials for the nanoparticles 563′ of different clusters 564a′, 564b′ to differentiate the different clusters from the incident light wave W that differs in one or more parameters. i1’ , W i2’ For the embodiment of FIG. 4, the light wave W i1’ , W i2’ However, in an alternative embodiment, the nanoparticles of different clusters 564a', 564b' may instead be focused on the light waves W i1’ , W i2’ 4, the different arrangements of clusters 564a' (triangular pattern) and 564b' (linear pattern) also result in each cluster generating and emitting light of a different wavelength.

[0057] The output lightwave W from cluster 564a' o1’ Output wavelength λ o1’ is the output light wave W from cluster 564b' o2’ Output wavelength λ o2’ Different output wavelength λ o1’, λ o2’ corresponds to different colors of light.

[0058] FIG. 5 shows a schematic diagram of a third embodiment of a layer of nanophotonic material 56″ overlying the front surface 512 of the window 51. The layer of nanophotonic material 56″ is provided as a layer of polymer-based film. The layer of nanophotonic material 56′ is formed from a crystalline lattice of gallium nitride (GaN) that defines a network of nanocavities 561″. The nanocavities 561″ are spaced apart from one another in a predetermined pattern or repeating arrangement. In contrast to the embodiments of FIGS. 3 and 4, the lattice of this third embodiment is fabricated to avoid or minimize the presence of discontinuities in the predetermined pattern or arrangement of the nanocavities 561″. Nanoparticles 563″ are dispersed throughout the lattice in a predetermined pattern and spacing arrangement, and are located between adjacent ones of the nanocavities 561″. The nanoparticles 563″ are in the form of quantum dots formed from indium gallium nitride (InGaN). The nanocavities 561″ are each sized to have a diameter ranging from 100 nm to 500 nm. Nanoparticles 563'' are sized to have diameters ranging from 9 nm to 120 nm.

[0059] The behavior of nanophotonic material 56'' overlying the front surface 512 of notification window 51 for the embodiment of Figure 5 will be described in response to the window being backlit by light waves generated by light source 61. Light source 61 responds to instructions provided by control circuitry provided on printed circuit board 8. 、 Incident light wave W i For the embodiment shown and described in FIG. 5, the incident light wave W i is the "p" component wavelength λ i.1 ,λ i.2… λ i.p In an alternative embodiment, the incident light wave W i may instead consist of a single wavelength.

[0060] The light source 61 emits an incident light wave W iTo generate W, the light wave first passes through window 51 and is incident on the layer of nanophotonic material 56′. When incident on nanophotonic material 56″, the individual nanocavities 561′ and nanoparticles 563′ act like slits in a diffraction grating, and the incident light wave W i The component wavelengths of the incident light wave W are diffracted. i A specific predetermined wavelength λ present in i.x The action of the individual nanocavities 561'' and nanoparticles 563'' in diffracting the incident light wave W is described below with reference to FIG. i As the incident light wave W passes through the nanophotonic material 56'', the nanocavities 561'' and nanoparticles 563'' diffract or deflect the component wavelengths present in the incident light wave. i The different component wavelengths present in the incident light wave W are diffracted by different amounts. i A predetermined wavelength component λ present in i.x The diffracted light wave W diff(λi.x) nc and W diff(λi.x) np The diffraction of the light waves W emanating from different ones of the nanocavities 561″ is shown in FIG. diff(λi.x) nc interfere with each other, and these interference regions are shown schematically as "R1" in FIG. 5. Similarly, the diffracted light waves W emanating from different ones of the nanoparticles 563" diff(λi.x) np The diffracted wave W diff(λi.x) nc The interference in the region "R1" is at wavelength λ i.x This results in a localized increase in the amplitude and intensity of light with a color corresponding to the diffracted wave W. diff(λi.x) np The interference in the region "R2" is at wavelength λ i.x results in a localized increase in the amplitude and intensity of light with a color corresponding to the incident light wave W iThe amount of diffraction of a given wavelength component present in the nanocavity 561'' is a function of the size of the individual nanocavities 561'' and nanoparticles 563''. Furthermore, the interference between different diffracted waves for a given wavelength, and the resulting increase in amplitude and intensity, is affected by the spacing between adjacent nanocavities 561'' and nanoparticles 563''. The incident light wave W i A given wavelength λ present in i.x corresponds to or is close to (e.g., within 50 nm) any one of one or more predetermined attenuation wavelengths of the window material 51, the interference of the diffracted light waves in the regions R1 and R2 and the corresponding increase in amplitude and intensity will be i.x This may help offset any initial decrease in the amplitude of

[0061] FIG. 6 shows a schematic diagram of a fourth embodiment of a layer of nanophotonic material 56″ overlying the front surface 512 of the window 51. The layer of nanophotonic material 56″ is formed from a crystalline lattice of gallium nitride (GaN) that defines a network of nanocavities 561″. The nanocavities 561′″ are spaced apart from one another in a predetermined pattern or repeating arrangement. In contrast to the embodiment of FIG. 5, no nanoparticles are provided within the layer of nanophotonic material 56″. The nanocavities 561′″ are each sized to have a diameter in the range of 100 nm to 500 nm.

[0062] The behavior of nanophotonic material 56''' overlying the front surface 512 of notification window 51 for the embodiment of FIG. 6 will be described in response to the window being backlit by light waves generated by light source 61, which responds to instructions provided by control circuitry provided on printed circuit board 8. 、 Incident light wave W i For the embodiment shown and described in FIG. 5, the incident light wave W i is the "p" component wavelength λ i.1 ,λ i.2… λ i.p In an alternative embodiment, the incident light wave W imay instead consist of a single wavelength.

[0063] The light source 61 emits an incident light wave W i , the light wave first passes through window 51 and is incident on the layer of nanophotonic material 56'''. Similar to the embodiment of FIG. 5, the individual nanocavities 561'' act like slits in a diffraction grating when incident on nanophotonic material 56'', causing the incident light wave W i The component wavelengths of the incident light wave W are diffracted. i A specific predetermined wavelength λ present in i.x The action of an individual nanocavity 561''' in diffracting an incident light wave W is described below with reference to FIG. i passes through the nanophotonic material 56'', the nanocavity 561'' diffracts or deflects the component wavelengths present in the incident light wave. i The different component wavelengths present in the incident light wave W are diffracted by different amounts. i λ of a given wavelength component present in i.x Diffracted light wave W' by nanocavity 561''' diff(λi.x) nc Diffraction into the nanocavity 561''' is shown in FIG. diff(λi.x) nc interfere with each other, and these interference regions are shown schematically as "R3" in Figure 6. i.1 Diffracted wave W' diff(λi.1) nc The interference in the region "R3" is at wavelength λ i.x resulting in a localized increase in the amplitude and intensity of light having a color corresponding to 。 Incident light wave W i The amount of diffraction of a given wavelength component present in the nanocavities 561''' is a function of the size of the individual nanocavities 561'''. Furthermore, the interference between the different diffracted waves for a given wavelength and the resulting changes in amplitude and intensity are affected by the spacing between adjacent nanocavities 561'''. Again, the incident light wave W i A given wavelength λ present in i.xcorresponds to or is close to (e.g., within 50 nm) any one of one or more predetermined attenuation wavelengths of the window material 51, the interference of the diffracted light waves in region R3 and the corresponding increase in amplitude and intensity will be the predetermined wavelength component λ of the incident light wave Wi caused by the attenuation effect of the window material. i.x This may help offset any initial decrease in the amplitude of

[0064] For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like are to be understood in all instances as modified by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Accordingly, in this context, the number "A" is to be understood as "A" ± 10%. Within this context, the number "A" can be considered to include a numerical value that is within the general standard error for the measurement of the property that the number "A" modifies. In some instances, the number "A," as used in the appended claims, may deviate by the percentages recited above, provided that the amount by which "A" deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. An aerosol generating device, comprising: A display device; Housing and a light source enclosed within the housing; The display device is Notification window and a nanophotonic material extending over the front surface of the window; the light source is in optical communication with the window for backlighting the window with light waves incident on the nanophotonic material; The nanophotonic material is configured to backlight the window and, in response to incident light waves comprising at least one predetermined wavelength incident on the nanophotonic material, increase the amplitude of the at least one predetermined wavelength and emit light waves comprising the at least one predetermined wavelength with the increased amplitude therefrom.

2. 2. The aerosol generating device of claim 1, wherein the nanophotonic material comprises a plurality of nanostructures, the nanostructures comprising either or a combination of nanocavities and nanoparticles, and the nanostructures are arranged, sized or formed to backlight the window and, in response to incident light waves comprising the at least one predetermined wavelength being incident on the nanophotonic material, increase the amplitude of the at least one predetermined wavelength and emit light waves comprising the at least one predetermined wavelength with the increased amplitude therefrom.

3. 3. The aerosol generating device of claim 2, wherein the plurality of nanostructures are arranged and sized to diffract incident light waves in response to backlighting the window and incident light waves comprising the at least one predetermined wavelength that are incident on the nanophotonic material.

4. The aerosol generating device of claim 3, wherein the plurality of nanostructures include at least a first diffraction portion and a second diffraction portion, the first and second diffraction portions being arranged and sized to diffract the at least one predetermined wavelength of the incident light wave by a predetermined amount, such that the diffracted light of the predetermined wavelength from the first diffraction portion and the diffracted light of the predetermined wavelength from the second diffraction portion intersect and reinforce each other.

5. 5. An aerosol generating device according to claim 1, wherein the nanophotonic material comprises a crystalline lattice defining a network of nanocavities.

6. 6. The aerosol generating device of claim 5, wherein individual nanoparticles or clusters of nanoparticles are provided within the crystal lattice between the nanocavities.

7. 7. An aerosol generating device according to claim 2, wherein the nanoparticles have a diameter in the range of 9 nm to 120 nm.

8. 8. The aerosol generating device according to claim 2, wherein the nanocavities have diameters in the range of 100 nm to 500 nm.

9. The display device is a dead-front display device, wherein the window comprises a material configured to attenuate light at one or more predetermined attenuation wavelengths, and the at least one predetermined wavelength is within 50 nm of the one or more predetermined attenuation wavelengths. An aerosol generating device as described in any one of claims 1 to 8.

10. 10. An aerosol generating device according to any preceding claim, wherein the nanophotonic material is provided as a layer of nanophotonic material extending over the front surface of the window.

11. 11. The aerosol generating device according to claim 1, further comprising a heating element configured to apply heat to an aerosol-forming substrate located within the aerosol generating device.

12. An aerosol generating device as described in any one of claims 1 to 11, wherein the window is a notification window whose color notifies the status of the device in response to the light source backlighting the window with light waves.

13. An aerosol generating device as described in any one of claims 1 to 12, wherein the aerosol generating device is a smoking article for generating an aerosol for inhalation by a user, or is configured to cooperate with the smoking article to induce the smoking article to generate an aerosol for inhalation by a user.

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