Abstract
A display is provided for an aerosol-generating device, the display including: a notification window; and a nano-photonic material extending over a front surface of the notification window, the nano-photonic material being configured to, in response to a light wave comprising at least one predetermined wavelength backlighting the notification window and being incident on the nano-photonic material, increase an amplitude of the at least one predetermined wavelength and emit therefrom a light wave comprising the at least one predetermined wavelength with the increased amplitude. An aerosol-generating device including the display is also provided.
Claims
1.-15. (canceled)
16. A display for an aerosol-generating device, the display comprising: a notification window; and a nano-photonic material extending over a front surface of the notification window, the nano-photonic material being configured to, in response to a light wave comprising at least one predetermined wavelength backlighting the notification window and being incident on the nano-photonic material, increase an amplitude of the at least one predetermined wavelength and emit therefrom a light wave comprising the at least one predetermined wavelength with the increased amplitude.
17. The display according to claim 16, wherein the nano-photonic material comprises a plurality of nano-structures, the nano-structures comprising either or a combination of nano-cavities and nano-particles, the nano-structures being arranged, sized, or formed to, in response to the light wave comprising the at least one predetermined wavelength backlighting the notification window and being incident on the nano-photonic material, increase the amplitude of the at least one predetermined wavelength and emit therefrom the light wave comprising the at least one predetermined wavelength with the increased amplitude.
18. The display according to claim 17, wherein the plurality of nano-structures are arranged and sized to, in response to the light wave comprising the at least one predetermined wavelength backlighting the notification window and being incident on the nano-photonic material, diffract the incident light wave.
19. The display according to claim 18, wherein the plurality of nano-structures comprise at least a first diffraction site and a second diffraction site, the first and the second diffraction sites being arranged and sized to each diffract the at least one predetermined wavelength of the incident light wave by a predetermined amount, such that the diffracted predetermined wavelength of light from the first diffraction site and the diffracted predetermined wavelength of light from the second diffraction site intersect with and reinforce each other.
20. The display according to claim 16, wherein the nano-photonic material is comprised of a crystalline lattice defining a network of nano-cavities.
21. The display according to claim 20, wherein individual nano-particles or clusters of nano-particles are provided in the crystalline lattice between the nano-cavities.
22. The display according to claim 17, wherein the nano-particles have a diameter in a range of between 9 nm to 120 nm.
23. The display according to claim 17, wherein the nano-cavities have a diameter in a range of between 100 nm to 500 nm.
24. The display according to claim 16, further comprising a light source in optical communication with the notification window and being configured to generate a light wave to backlight the notification window, the light wave comprising the at least one predetermined wavelength.
25. The display according to claim 16, wherein the display is a dead-front display in which the notification window comprises a material configured to attenuate light at one or more predetermined attenuation wavelengths, and wherein the at least one predetermined wavelength is within 50 nm of the one or more predetermined attenuation wavelengths.
26. The display according to claim 16, wherein the nano-photonic material is provided as a layer of nano-photonic material extending over the front surface of the notification window.
27. An aerosol-generating device comprising the display according to claim 16, wherein the aerosol-generating device further comprises: a housing, wherein the display is integrated into the housing; and a light source enclosed within the housing and in optical communication with the notification window for backlighting the notification window with a light wave to fall incident on the nano-photonic material.
28. The aerosol-generating device according to claim 27, wherein the aerosol-generating device further comprises a heating element configured to apply heat to an aerosol-forming substrate located within the aerosol-generating device.
29. The aerosol-generating device according to claim 27, wherein a color of the notification window in response to the light source backlighting the notification window with a light wave provides a notification of a status of the aerosol-generating device.
30. The aerosol-generating device according to claim 27, wherein the aerosol-generating device is a smoking article configured to generate aerosol for inhalation by a user, or being configured to cooperate with a smoking article so as to induce the smoking article to generate aerosol for inhalation by a user.
Description
[0073] Examples will now be further described with reference to the figures, in which:
[0074] FIG. 1 shows a schematic view of an aerosol-generating device provided with a display.
[0075] FIG. 2 shows a cross-sectional view of the aerosol-generating device of FIG. 1 along line A-A of FIG. 1 (including a detail view of the display).
[0076] FIG. 3 shows a cross-sectional schematic view of a first embodiment of a display for use with the aerosol-generating device of FIG. 1.
[0077] FIG. 4 shows a cross-sectional view schematic of a second embodiment of a display for use with the aerosol-generating device of FIG. 1.
[0078] FIG. 5 shows a cross-sectional schematic view of a third embodiment of a display for use with the aerosol-generating device of FIG. 1.
[0079] FIG. 6 shows a cross-sectional schematic view of a fourth embodiment of a display for use with the aerosol-generating device of FIG. 1.
[0080] FIG. 1 shows an aerosol-generating device 1. The aerosol-generating device 1 is elongate and generally cylindrical in cross-section, with a housing 2 having an upper part 2a and a lower part 2b. The parts 2a, 2b of the housing mate with each other at a diagonal interface 3. A display 4 is integrated into the housing 2. The display includes four notification windows 51, 52, 53, 54. The notification windows 51, 52, 53, 54 define icons of different shapes. The aerosol-generating device 1 is sized in length and diameter so as to be suitable for being held between the thumb and fingers of a user. The aerosol-generating device 1 shown in FIG. 1 is a smoking article for generating smoke for inhalation by a user. Although not shown in the figures, a replaceable cartridge containing aerosol-forming substrate and an electrically-powered heating element are enclosed within the housing 2 of the device 1, with the heating element operable to apply heat to the aerosol-forming substrate to generate an inhalable aerosol therefrom, for inhaling from an opening in the upper part 2a of the housing 2 of the device 1. This inhalable aerosol is represented by the array of dashed lines in FIG. 1 emanating from the upper part 2a of the housing 2.
[0081] FIG. 2 shows a cross-sectional view of the aerosol-generating device 1 along line A-A of FIG. 1, corresponding to the location of the lowermost notification window 51 of the display 4. An accompanying detail view localised on the notification window 51 is also provided in FIG. 2. A light source 61 is located within a cavity 71 provided inside the housing 2. For the embodiment shown, the light source 61 is a light-emitting diode (LED). The light source 61 is mounted on a printed circuit board 8 which contains 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 provides power to the heating element (not shown) used to apply heat to the aerosol-forming substrate (also not shown). For the embodiment shown in FIG. 2, the power source 9 is a rechargeable battery. The cavity 71 is arranged such that the light source 61 is in optical communication with a back-facing surface 511 of the notification window 51. In use, the light source 61 illuminates the back-facing surface 511 of the notification window 51 with a light wave to thereby backlight the window for viewing by a user of the device 1. The cavity 71 is arranged such that a light wave from the light source 61 backlights the window 51 without illuminating any of the other three notification windows 52, 53, 54 of the display 4. The printed circuit board 8 extends for the length of the display 4. Three additional light sources (not shown) are mounted on the printed circuit board 8 and are located within respective cavities (also not shown) for backlighting each of the remaining three notification windows 52, 53, 54. The configuration of the light source 61 and the notification window 51 is indicative of the configuration of the notification windows 52, 53, 54 and their own respective light sources.
[0082] For the aerosol-generating device 1, the display 4 is a dead-front display, in which each of the windows 51, 52, 53, 54 appear tinted when viewed from outside of the device, so as to correspond in colour to the housing 2 when their respective light sources (for example, light source 61 for window 51) are inactive. The window 51 is made of a polymer configured to attenuate light at one or more predetermined attenuation wavelengths, thereby imparting a tint to the window 51. A layer of nano-photonic material 56 overlies a front-facing surface 512 of the window 51 (see FIG. 2).
[0083] FIG. 3 shows a schematic representation of a first embodiment of the layer of nano-photonic material 56 overlying the front-facing surface 512 of the window 51. The layer of nano-photonic material 56 is provided as a layer of a polymer-based film. The layer of nano-photonic material 56 is formed of a crystalline lattice of gallium nitride (GaN) defining a network of nano-cavities 561. The nano-cavities 561 are spaced apart from each other in a predetermined pattern or repeating arrangement. However, the lattice is fabricated so as to define discontinuities in the predetermined pattern or arrangement of nano-cavities 561. These discontinuities are located in regions 562a to 562f of the crystalline lattice. The discontinuities in regions 562a to 562c define a triangular pattern, as do the discontinuities in regions 562d to 562f. For the embodiment shown in FIG. 3, each discontinuity region 562a to 562f contains a group of nano-particles 563 in the form of quantum dots formed of indium gallium nitride (InGaN). As can be seen from FIG. 3, the nano-photonic material 56 has been fabricated to provide clusters 564a, 564b of the groups of nano-particles 563. For the embodiment shown in FIG. 3, each cluster 564a, 564b consists of three groups of nano-particles 563 arranged in a triangular configuration. The six groups of nano-particles 563 (three per cluster 564a, 564b) are located in the six discontinuity regions 562a to 562f of the crystalline lattice. The nano-cavities 561 are each sized to have a diameter in a range of between 100 nm to 500 nm. The nano-particles 563 are sized to have diameters in a range of between 9 nm to 120 nm.
[0084] The behaviour of the nano-photonic material 56 overlying the front-facing surface 512 of the notification window 51 for the embodiment of FIG. 3 is discussed in response to the window being backlit by a light wave generated by light source 61. The light source 61 is configured to generate first and second incident light waves W.sub.i1 and W.sub.i2 at different points in time, dependent on and according to instructions provided by the control circuitry provided on the printed circuit board 8. For the embodiment shown and described in FIG. 3, the first and second incident light waves W.sub.i1 and W.sub.i2 have distinct wavelength compositions. For the illustrated embodiment, the first incident light wave W.sub.i1 is composed of “m” constituent wavelengths to provide a wavelength composition of λ.sub.i1.1, λ.sub.i1.2 . . . λ.sub.i1.m; and the second incident light wave W.sub.i2 is composed of “n” constituent wavelengths to provide a wavelength composition of λ.sub.i2.1, λ.sub.i2.2 . . . λ.sub.i2.n. The wavelength composition of the first incident light wave W.sub.i1 is different to that the second incident light wave W.sub.i2. In an alternative embodiment, the first and second incident light waves W.sub.i1 and W.sub.i2 may each instead consist of a single wavelength, with the wavelength of the first incident light wave W.sub.i1 being different to that of the second incident light wave W.sub.i2.
[0085] When the light source generates first incident light wave W.sub.i1, the light wave W.sub.i1 first passes through the window 51 to fall incident on the layer of nano-photonic material 56. On entering the nano-photonic material 56, the light wave W.sub.i1 has the effect of driving or energising the clusters 564a, 564b of the groups of nano-particles 563 to plasmonically resonate. For the example of FIG. 3, the wavelength composition λ.sub.i1.1, λ.sub.i1.2 . . . λ.sub.i1.m of the light wave W.sub.i1 generated by light source 61 is selected to not include any of one or more predetermined attenuation wavelengths of the window material 51. This helps to ensure that the light wave W.sub.i1, when falling incident upon the layer of nano-photonic material 56, after having passed between the back-facing and front-facing surfaces 511, 512 of the window 51, retains sufficient amplitude and energy to drive each of the clusters 564a, 564a of the groups of nano-particles 563 to plasmonically resonate. For the example shown in FIG. 3, the arrangement and size of the clusters 564a, 564b and their respective nano-particles 563 is such that each cluster 564a, 564b generates and radiates an output light wave W.sub.o1′ having an output wavelength λ.sub.o1 corresponding to a desired or predetermined colour of light. Accordingly, to a person viewing the window 51 of the display 4 when backlit by the light source 61, the window appears to be illuminated with a colour corresponding to the output wavelength λ.sub.o1.
[0086] When the light source 61 is switched, by virtue of instructions provided by the control circuitry of the printed circuit board 8, to generate the second light wave W.sub.i2 having the second wavelength composition λ.sub.i2.1, λ.sub.i2.2 . . . λ.sub.i2.n, the light wave W.sub.i2 passes through the window 51 to fall incident upon the layer of nano-photonic material 56. As for light wave W.sub.i1, light wave W.sub.i2 also has the effect of driving or energising the clusters 564a, 564b of the groups of nano-particles 563 to plasmonically resonate. Again, the wavelength composition λ.sub.i2.1, λ.sub.i2.2 . . . λ.sub.i2.n of the light wave W.sub.i2 generated by the light source 61 is selected to not include any of one or more predetermined attenuation wavelengths of the window material 51, so as to ensure that the light wave W.sub.i2 retains sufficient amplitude and energy to drive the clusters 564a, 564b to plasmonically resonate. The arrangement, size and material of the clusters 564a, 564b of nano-particles 563 is such that each cluster 564a, 564b generates and radiates an output light wave W.sub.o2 having an output wavelength λ.sub.o2 corresponding to a desired or predetermined colour of light. The output wavelength λ.sub.o2 of output light wave W.sub.o2 is different to the output wavelength λ.sub.o1 of output light wave W.sub.o1. So, the light waves Wi1, W.sub.i2 with their different wavelength compositions (λ.sub.i1.1, λ.sub.i1.2 . . . λ.sub.i1.m), (λ.sub.i2.1, λ.sub.i2.2 . . . λ.sub.i2.n) drive the clusters 564a, 564a to each generate and radiate different output light waves W.sub.o1, W.sub.o2 consisting of different respective output wavelengths λ.sub.o1, λ.sub.o2. The different output wavelengths λ.sub.o1, λ.sub.o2 correspond to different colours of light. So, a person viewing the window 51 of the display 4 when backlit with light wave W.sub.i1 having wavelength composition λ.sub.i1.1, λ.sub.i1.2 . . . λ.sub.i1.m will see the window appear illuminated with a different colour compared to when the window 51 is backlit with light wave W.sub.i2 having wavelength composition λ.sub.i2.1, λ.sub.i2.2 . . . λ.sub.i2.n. The different colours can be indicative of the status of the aerosol-generating device at a given time. For example, an output wavelength λ.sub.o1 of about 470 nm (corresponding generally to a blue colour of light) may be indicative of the heating element of the aerosol-generating device 1 not yet having reached its design operating temperature, whereas an output wavelength of λ.sub.o2 of about 530 nm (corresponding generally to a green colour of light) may be indicative of the heating element having attained its design operating temperature. Of course in other embodiments, the clusters 564a, 564b of nano-particles 563 may be arranged, sized or formed of a material such that they generate and radiate light at an output wavelength corresponding to different colours.
[0087] FIG. 4 shows a schematic representation of a second embodiment of the layer of nano-photonic material 56′ overlying the front-facing surface 512 of the window 51. The layer of nano-photonic material 56′ is formed of a crystalline lattice defining a network of nano-cavities 561′. The nano-cavities 561′ are spaced apart from each other in a predetermined pattern or repeating arrangement. In common with the embodiment of FIG. 3, the lattice is fabricated so as to define discontinuities in the predetermined pattern or arrangement of nano-cavities 561′. These discontinuities are located in regions 562a′ to 562e′ of the crystalline lattice. The discontinuities in regions 562a′ to 562c′ define a triangular pattern, whereas the discontinuities in regions 562d′ to 562e′ define a linear pattern. Each discontinuity region 562a′ to 562e′ contains a group of nano-particles 563′ in the form of quantum dots. As can be seen from FIG. 4, the nano-photonic material 56′ has been fabricated to provide clusters 564a′, 564b′ of the groups of nano-particles 563′. For the embodiment of FIG. 4, cluster 564a′ consists of three groups of nano-particles 563′ in a triangular arrangement and cluster 564b′ consists of two groups of nano-particles 563′ in a linear arrangement. The five groups of nano-particles 563′ are located in the five discontinuity regions 562a′ to 562e′. As for the embodiment of FIG. 3, the nano-cavities 561′ are each sized to have a diameter in a range of between 100 nm to 500 nm, and the nano-particles 563′ sized to have diameters in a range of between 9 nm to 120 nm. However, the nano-particles in cluster 564a′ are formed of a material differing in composition from that of the nano-particles in cluster 564b′. As explained below, the use of different materials for the nano-particles 563′ of the different clusters 564a′, 564b′ results in the nano-particles 563′ of the different clusters 564a′, 564b′ responding differently to two different incident light waves, with the differing response being dependent on differences in one or more parameters between two such incident light waves.
[0088] The behaviour of the nano-photonic material 56′ overlying the front-facing surface 512 of the notification window 51 for the embodiment of FIG. 4 is discussed in response to the window being backlit by a light wave generated by light source 61. The light source 61 is configured to generate first and second light waves W.sub.i1′ and W.sub.i2′ at different points in time, dependent on and according to instructions provided by the control circuitry provided on the printed circuit board 8. For the embodiment described, the incident light waves W.sub.i1′ and W.sub.i2′ have distinct wavelength compositions. For the illustrated embodiment, the first incident light wave W.sub.i1′ is composed of “m” constituent wavelengths to provide a wavelength composition of λ.sub.i1′.1, λ.sub.i1′.2 . . . λ.sub.i1′.m; and the second incident light wave W.sub.i2′ is composed of “n” constituent wavelengths to provide a wavelength composition of λ.sub.i2′.1, λ.sub.i2′.2 . . . λ.sub.i2′.n. The wavelength composition of the first incident light wave W.sub.i1′ is different to that the second incident light wave W.sub.i2′. In an alternative embodiment, the first and second incident light waves W.sub.i1′ and W.sub.i2′ may each instead consist of a single wavelength, with the wavelength of the first incident light wave W.sub.i1′ being different to that of the second incident light wave W.sub.i2′.
[0089] When the light source generates first incident light wave W.sub.i1′, the light wave W.sub.i1′ first passes through the window 51 to fall incident on the layer of nano-photonic material 56′. On entering the nano-photonic material 56′, the light wave W.sub.i1′ drives and energises the cluster 564a′ of nano-particles 563 to plasmonically resonate. The arrangement, size and material of the cluster 564a′ and its respective nano-particles 563′ result in the cluster 564a′ generating and radiating an output light wave W.sub.o1′ having an output wavelength λ.sub.o1′ corresponding to a desired or predetermined colour of light. However, the different material used for the nano-particles 563′ of cluster 564b′ is such that the nano-particles 563′ of cluster 564b′ are unresponsive to the first incident light wave W.sub.i1′ consisting of wavelength composition λ.sub.i1′.1, λ.sub.i1′.2 . . . λ.sub.i1′.m, resulting in no or negligible plasmonic resonance of the nano-particles 563′ of cluster 564b′. So, to a person viewing the window 51 of the display 4 when the window is backlit by light wave W.sub.i1′ with wavelength composition λ.sub.i1′.1, λ.sub.i1′.2 . . . λ.sub.i1′.m, the window would appear illuminated with a colour corresponding to the output wavelength λ.sub.o1′ of the light generated and radiated by cluster 564a′ only.
[0090] When the light source 61 is switched, by virtue of instructions provided on the control circuitry of the printed circuit board 8, to generate the second incident light wave W.sub.i2′ having second wavelength composition λ.sub.i2′.1, λ.sub.i2′.2 . . . λ.sub.i2′.n, the light wave W.sub.i2′ passes through the window 51 to fall incident upon the layer of nano-photonic material 56′. On entering the nano-photonic material 56′, the light wave W.sub.i2′ drives and energises the cluster 564b′ of nano-particles 563′ to plasmonically resonate. The arrangement and size of the cluster 564b′ and its constituent nano-particles 563′ results in the cluster 564b′ generating and radiating an output light wave W.sub.o2′ having an output wavelength λ.sub.o2′ corresponding to a desired or predetermined colour of light. However, the different material used for the nano-particles 563′ of cluster 564a′ is such that the nano-particles 563′ of cluster 564a′ are unresponsive to the second incident light wave W.sub.i2′ consisting of wavelength composition λ.sub.i2′.1, λ.sub.i2′.2 . . . λ.sub.i2′.n, resulting in no or negligible plasmonic resonance of the nano-particles 563′ of cluster 564a′. So, to a person viewing the window 51 of the display 4 when the window is backlit by light wave W.sub.i2′ with wavelength composition λ.sub.i2′.1, λ.sub.i2′.2 . . . λ.sub.i2′.n, the window would appear illuminated with a colour corresponding to the output wavelength λ.sub.o2′ of the light generated and radiated by cluster 564b′ only.
[0091] The embodiment of FIG. 4 illustrates how the use of different materials for the nano-particles 563′ of the different clusters 564a′, 564b′ can result in these different clusters reacting differently to incident light waves W.sub.i1′, W.sub.i2′ differing in one or more parameters. For the embodiment of FIG. 4, the light waves W.sub.i1′, W.sub.i2′ differ in their wavelength composition. However, in alternative embodiments, the nano-particles of the different clusters 564a′, 564b′ may instead react differently according to differences in the frequency and/or amplitude of the light waves W.sub.i1′, W.sub.i2′. Further, for the embodiment shown in FIG. 4, the different arrangement of the clusters 564a′ (triangular pattern) and 564b′ (linear pattern) also results in each cluster generating and radiating light of different wavelengths.
[0092] The output wavelength λ.sub.o1′ of output light wave W.sub.o1′ from cluster 564a′ is different to the output wavelength λ.sub.o2′ of output light wave W.sub.o2′ from cluster 564b′. The different output wavelengths λ.sub.o1′, λ.sub.o2′ correspond to different colours of light.
[0093] FIG. 5 shows a schematic representation of a third embodiment of the layer of nano-photonic material 56″ overlying the front-facing surface 512 of the window 51. The layer of nano-photonic material 56″ is provided as a layer of a polymer-based film. The layer of nano-photonic material 56″ is formed of a crystalline lattice of gallium nitride (GaN) defining a network of nano-cavities 561″. The nano-cavities 561″ are spaced apart from each other in a predetermined pattern or repeating arrangement. In contrast to the embodiments of FIGS. 3 and 4, the lattice for this third embodiment is fabricated to avoid or minimise the presence of discontinuities in the predetermined pattern or arrangement of nano-cavities 561″. Nano-particles 563″ are dispersed throughout the lattice in a predetermined pattern and spacing, being located between adjacent ones of the nano-cavities 561″. The nano-particles 563″ are in the form of quantum dots formed of indium gallium nitride (InGaN). The nano-cavities 561″ are each sized to have a diameter in a range of between 100 nm to 500 nm. The nano-particles 563″ are sized to have diameters in a range of between 9 nm to 120 nm.
[0094] The behaviour of the nano-photonic material 56″ overlying the front-facing surface 512 of the notification window 51 for the embodiment of FIG. 5 is discussed in response to the window being backlit by a light wave generated by light source 61. The light source 61 is configured to generate incident light wave W.sub.i, according to instructions provided by control circuitry provided on the printed circuit board 8. For the embodiment shown and described in FIG. 5, the incident light wave W.sub.i has a wavelength composition consisting of “p” constituent wavelengths λ.sub.i.1, λ.sub.i.2 . . . λ.sub.i.p. In an alternative embodiment, the incident light wave W.sub.i may instead consist of a single wavelength.
[0095] When the light source 61 generates incident light wave W.sub.i, the light wave first passes through the window 51 to fall incident on the layer of nano-photonic material 56″. On entering the nano-photonic material 56″, the individual nano-cavities 561″ and nano-particles 563″ function like the slits of a diffraction grating, to diffract the constituent wavelengths of the incident light wave W.sub.i. The action of the individual nano-cavities 561″ and nano-particles 563″ in diffracting a specific predetermined wavelength λ.sub.i.x present in the incident light wave W.sub.i is discussed below with reference to FIG. 5. As the incident light wave W.sub.i passes through the nano-photonic material 56″, the nano-cavities 561″ and nano-particles 563″ diffract or deflect the constituent wavelengths present in the incident light wave. Different constituent wavelengths present in the incident light wave W.sub.i are diffracted by different amounts. The diffraction by nano-cavities 561″ and nano-particles 563″ of the predetermined wavelength component λ.sub.i.x present in incident light wave W.sub.i into diffracted light waves W.sub.diff(λi.x).sup.nc and W.sub.diff(λi.x).sup.np respectively is shown in FIG. 5. The diffracted light waves W.sub.diff(λi.x).sup.nc emanating from different ones of the nano-cavities 561″ interfere with each other, with these regions of interference indicated schematically as “R1” in FIG. 5. Similarly, the diffracted light waves W.sub.diff(λi.x).sup.np emanating from different ones of the nano-particles 563″ also interfere with each other, with these regions of interference indicated schematically as “R2” in FIG. 5. The interference in regions “R1” of the diffracted waves W.sub.diff(λi.x).sup.n results in localised increases in amplitude and intensity of light having a colour corresponding to wavelength λ.sub.i.x. Similarly, the interference in regions “R2” of the diffracted waves W.sub.diff(λi.x).sup.np results in localised increases in amplitude and intensity of light having a colour corresponding to wavelength λ.sub.i.x. The amount of diffraction for a given wavelength component present in the incident light wave W.sub.i is a function of the size of the individual nano-cavities 561″ and nano-particles 563″. Further, the interference between different diffracted waves for a given wavelength and the resulting increase in amplitude and intensity is influenced by the spacing between adjacent ones of the nano-cavities 561″ and the nano-particles 563″. Where the predetermined wavelength λ.sub.i.x present in the incident light wave W.sub.i corresponds to or is close to (for example, within 50 nm) any of the one or more predetermined attenuation wavelengths of the window material 51, the interference of the diffracted light waves in regions R1 and R2 and corresponding increase in amplitude and intensity can help to offset any initial reduction in amplitude of the predetermined wavelength component λ.sub.i.x of the incident light wave W.sub.i caused by the attenuating effect of the window material 51.
[0096] FIG. 6 shows a schematic representation of a fourth embodiment of the layer of nano-photonic material 56′′ overlying the front-facing surface 512 of the window 51. The layer of nano-photonic material 56′′ is formed of a crystalline lattice of gallium nitride (GaN) defining a network of nano-cavities 561″′. The nano-cavities 561″′ are spaced apart from each other in a predetermined pattern or repeating arrangement. In contrast to the embodiment of FIG. 5, no nano-particles are provided within the layer of nano-photonic material 56″′. The nano-cavities 561″′ are each sized to have a diameter in a range of between 100 nm to 500 nm.
[0097] The behaviour of the nano-photonic material 56″′ overlying the front-facing surface 512 of the notification window 51 for the embodiment of FIG. 6 is discussed in response to the window being backlit by a light wave generated by light source 61. The light source 61 is configured to generate incident light wave W.sub.i, according to instructions provided by control circuitry provided on the printed circuit board 8. As for the embodiment shown and described in FIG. 5, the incident light wave W.sub.i has a wavelength composition which consisting of “p” constituent wavelengths λ.sub.i.1, λ.sub.i.2 . . . λ.sub.i.p. In an alternative embodiment, the incident light wave W.sub.i may instead consist of a single wavelength.
[0098] When the light source 61 generates incident light wave W.sub.i, the light wave first passes through the window 51 to fall incident on the layer of nano-photonic material 56″′. In a similar manner to the embodiment of FIG. 5, on entering the nano-photonic material 56″′, the individual nano-cavities 561″′ function like the slits of a diffraction grating to diffract the constituent wavelengths of the incident light wave W.sub.i. The action of the individual nano-cavities 561″′ in diffracting a specific predetermined wavelength λ.sub.i.x present in the incident light wave W.sub.i is discussed below with reference to FIG. 6. As the incident light wave W.sub.i passes through the nano-photonic material 56″′, the nano-cavities 561″′ diffract or deflect the constituent wavelengths present in the incident light wave. Different constituent wavelengths present in the incident light wave W.sub.i are diffracted by different amounts. The diffraction by nano-cavities 561″′ of the predetermined wavelength component λ.sub.i.x present in the incident light wave W.sub.i into diffracted light waves W′.sub.diff(λi.x).sup.nc is shown in FIG. 6. The diffracted light waves W′.sub.diff(λi.x).sup.nc emanating from different ones of the nano-cavities 561″′ interfere with each other, with these regions of interference indicated schematically as “R3” in FIG. 6. The interference in regions “R3” of the diffracted waves W′.sub.diff(λi.x).sup.nc for wavelength λ.sub.i.1 results in localised increases in amplitude and intensity of light having a colour corresponding to the wavelength λ.sub.i.x. The amount of diffraction for a given wavelength component present in the incident light wave W.sub.i is a function of the size of the individual nano-cavities 561″′. Further, the interference in between different diffracted waves for a given wavelength and the resulting change in amplitude and intensity is influenced by the spacing between adjacent ones of the nano-cavities 561″′. Again, where the predetermined wavelength λ.sub.i.x present in the incident light wave W.sub.i corresponds to or is close to (for example, within 50 nm) of any of the one or more predetermined attenuation wavelengths of the window material 51, the interference of the diffracted light waves in regions R3 and corresponding increase in amplitude and intensity can help to offset any initial reduction in amplitude of the predetermined wavelength component λ.sub.i.x in the incident light wave W.sub.i caused by the attenuating effect of the window material.
[0099] For the purpose of the present description and of the appended claims, except where otherwise indicated, all numbers expressing amounts, quantities, percentages, and so forth, are to be understood as being modified in all instances by the term “about”. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein. In this context, therefore, a number “A” is understood as “A”±10% of “A”. Within this context, a number “A” may be considered to include numerical values that are within general standard error for the measurement of the property that the number “A” modifies. The number “A”, in some instances as used in the appended claims, may deviate by the percentages enumerated above provided that the amount by which “A” deviates does not materially affect the basic and novel characteristic(s) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed and include any intermediate ranges therein, which may or may not be specifically enumerated herein.
