AIRCRAFT LIGHTING SYSTEM

Abstract

An aircraft cabin lighting system comprises one or more cabin lighting units, each cabin lighting unit including an emergency exit sign arranged to be electrically illuminated; and one or more luminescent emergency exit signs 1. The luminescent emergency exit signs 1 are portable and each includes an adhesive layer 3 arranged to allow the luminescent emergency exit sign 1 to adhere to a surface. The signs 1 are arranged to adhere to a surface in proximity to the electrically illuminated emergency exit sign in use and do not require electricity to operate. Figure to be published with the abbreviation: Figure 1

Description

Description Title of the invention: LIGHTING SYSTEM FOR AIRCRAFT TECHNICAL FIELD OF THE INVENTION The present invention relates to emergency exit lighting systems in an aircraft, and in particular methods for managing the failure of one or more electrical emergency exit signs, and aircraft cabin lighting systems arranged to allow such a failure to be dealt with without immobilizing the aircraft on the ground for a prolonged period. TECHNOLOGICAL BACKGROUND OF THE INVENTION These signs can be used to help passengers escape the aircraft in an emergency, particularly by enabling the identification of exits even if problems such as smoke or an electrical fault in other cabin lighting systems impair visibility. The amount and location of smoke, among other factors, can influence where people look for the signs—high-level and low-level signs can be used, optionally in addition to floor markings. It is worth noting that many emergency exit signs in aircraft cabins are positioned relatively low, near the cabin floor, and can therefore be described as low-level lighting systems. Such signs can be part of an evacuation system designed to guide people to and identify an exit, for example, in combination with floor markings.High-level markings may also be provided, for example in the form of progression signs directing observers to the nearest exit. These high-level markings may need to be visible from a greater distance than low-level markings (for example, about 12 meters or more instead of 4 to 5 meters), for example with signs for each of two adjacent emergency exits visible from a third emergency exit located between the two. In commercial passenger aircraft in particular, there are typically specific safety regulations and requirements. It is common practice to equip emergency exit signs with electric lighting to make them more visible. In aircraft cabins, it is generally required that all passenger aircraft be equipped with illuminated emergency exit signs near all emergency exits. For example, Certification Specification 25 (CS 25) covers regulations for large aircraft, specifically sections CS 25.811 and CS 25.812. If even one emergency exit sign is defective (by For example, due to a blown bulb, a failed LED, or an electrical fault, the aircraft may be in breach of standards and may be grounded until repaired, or forced to return to a technical base empty / without passengers if the airport where the fault occurred is not a technical base, or may be required to complete the scheduled flight with fewer passengers (for example, standards regarding the maximum number of passengers per functioning emergency exit may mean that the number of passengers for an exit may not be permitted to fly if the exit indicator light is out of order). Each of these eventualities can be very costly for an airline and is therefore desirable to avoid.It will be appreciated if some signs have many individual lights, and if some of these individual bulbs or LEDs are defective without violating the Minimum Minimum Equipment List (MMEL) standards—for example, the standard may specify that at least three of the five bulbs in each sign must be functioning for the aircraft to be considered fit to fly with passengers. A sign can therefore be described as "defective" when it falls below the required minimum standard (or falls at the minimum standard, depending on the safety rules regarding redundancy), whether one or more lights in that sign are still operational or not. Summary of the invention According to one aspect, an aircraft cabin lighting system is proposed, comprising one or more cabin lighting units, each cabin lighting unit including an electrically illuminated emergency exit sign; and one or more non-electrically illuminated (luminescent) emergency exit signs. The non-electrically illuminated luminescent emergency exit signs are portable and each includes an adhesive layer designed to allow the sign to adhere to a surface. The signs are designed to adhere to a surface in close proximity to the electrically illuminated emergency exit sign in use. Multiple luminous emergency exit signs can be used simultaneously in a particular aircraft cabin during the same flight. As used here, "luminescent" is defined as being widely used in chemistry to refer to the emission of radiation (usually visible light) by chemical reactions that do not involve the significant release of heat or electric current. This definition contrasts with the light emitted by incandescent bodies, such as burning fuels, molten iron, and wires heated by an electric current. "Electroluminescence," such The luminescence seen in light-emitting diodes is the result of an electric current passing through a substance, not a chemical change, and is not included in the scope of "luminescence" as used here. The luminescent materials described here do not require electricity to produce luminescence, unlike the electrically illuminated emergency exit signs they replace. Luminescent signs can be photoluminescent. Photoluminescent signs can be charged by exposure to light and subsequently become luminous. In this case, the photoluminescent material(s) are supplied with energy (in the form of radiation) to enable them to produce luminescence. Luminescent signs can be chemiluminescent. Chemiluminescent signs can be activated by deformation of the sign and subsequently become luminous. As such, chemiluminescent signs illuminate themselves (once activated / "lit up"), and no charge is required. In some embodiments, luminescent signs may contain both one or more photoluminescent and chemiluminescent materials, and / or materials exhibiting other types of luminescence (e.g., bioluminescence). Each electrical emergency exit sign may be a low-level exit sign, and optionally may be: (1) located adjacent to a lower corner of an emergency exit; and / or (ii) located less than 122 cm, and optionally less than 50 cm, above of an aircraft cabin floor. Low-level signs can identify a specific emergency exit, in particular by indicating that the emergency exit is in the immediate vicinity of the sign. In alternative or additional embodiments, the emergency exit sign(s) may be a high-level exit sign, which is optionally located at least 122 cm above an aircraft cabin floor. High-level signs may be located adjacent to an aircraft cabin ceiling, optionally on a side wall, or on a protrusion or luminaire extending downward from the ceiling. High-level signs can point to one or more emergency exits and can be used to direct a passenger to a suitable emergency exit. Each luminescent emergency exit sign can be flexible so that it can conform to the shape of the surface to which it is applied. In some embodiments with chemiluminescent signs, pressing applying pressure to the sign to set it up may be sufficient to activate the chemically luminescent material. Each luminescent emergency exit sign can be sized and / or shaped to cover the electrical emergency exit sign when the adhesive layer is applied to it. The adhesive layer can be designed to be peelable from the surface of the electrical emergency exit sign, allowing the illuminated emergency exit sign to be temporarily installed and then removed without damaging the sign. The adhesive layer can therefore be removable, providing an easy-to-peel label. Alternatively, the adhesive layer can be designed to adhere firmly to the surface, making the sign difficult to remove and, optionally, impossible to remove without damaging it. Such embodiments can reduce the risk of damage. These signs can be reused, for example, by applying a fresh layer of adhesive after removing the first, or they can be single-use and discarded after use. Each luminescent emergency exit sign may include a luminescent layer and an exit identifier arranged to be illuminated by the luminescent layer. It will be appreciated if the luminescence generally produces a glow, and not a bright illumination, but that this glow can still illuminate an exit identifier – either by causing the exit identifier to produce a glow, or by causing a surrounding area of ​​the exit identifier to produce a glow, so that the darker identifier is visible by contrast. Various luminescence colors can be chosen. For example, a photoluminescent sign or layer can be arranged to emit blue or green light, and / or a chemiluminescent sign or layer can be arranged to emit one or more colors from among red, green, blue, white, or infrared light. The color can be chosen based on passenger expectations for emergency signage, with red (e.g., the text "EXIT") and green (e.g., the image of a person running) being common in current exit identifiers. The issue identifier can include one or more words and / or symbols. The words and / or symbols can be: (1) formed by conformation of the luminescent layer; and / or (ii) formed by masking part of the luminescent layer. It will be appreciated if multiple different identifiers can be provided on a single sign, and if different identifiers on the same sign can optionally be formed in different ways. When a photoluminescent material is used, the photoluminescent layer can be arranged so that it can be charged with ambient cabin light. The photoluminescent emergency exit sign can be arranged to be charged using light with a wavelength in the range of 350 nm to 500 nm. For photoluminescent emergency exit signs, the aircraft cabin lighting system may further include a dedicated charging light arranged to charge the photoluminescent emergency exit sign. In such embodiments, the dedicated charging light may be a spotlight—for example, a spotlight installed on a runway, an airport terminal building, or another structure—and may be a permanent fixture or a portable light, or it may be a torch. The dedicated charging light can be arranged to charge the photoluminescent emergency exit sign before it is adhered to the surface. The sign can therefore be kept near a charging light to minimize charging time. In embodiments where the luminescent emergency exit sign is a chemiluminescent emergency exit sign, the sign may be arranged to be activated by deformation of the chemiluminescent layer. For example, a user may manually "break," bend, press on, and / or massage the sign to obtain luminescence. The user may be encouraged to deform the sign until a steady, bright glow is provided. It will be appreciated if, in this context, the term "break" is to be interpreted as for a glow stick—a barrier within the sign may be broken / cracked so as to allow the chemicals to mix, causing a chemical reaction that provides chemiluminescence, but the sign itself is not broken or shattered. Activation of the sign may take less than 10 seconds, and optionally less than five seconds. According to a second aspect, a method for providing emergency exit lighting in an aircraft cabin is proposed. The method includes, in response to a failure of an electrical emergency exit sign: obtaining a luminous emergency exit sign from the storage, the luminescent emergency exit sign comprising a layer adhesive arranged to allow the exit sign to adhere luminescent relief to a surface; the charging and / or activation of the illuminated emergency exit sign; and the application of the luminescent emergency exit sign on a surface to proximity of the faulty electrical emergency exit sign so that the adhesive layer holds it in place as an exit sign replacement backup. The luminescent emergency exit sign can be as described in the first aspect. The process can be carried out using the device of the first aspect. A charging step and an activation step can both be carried out, particularly in embodiments with signs containing both chemiluminescent and photoluminescent materials. In embodiments using photoluminescent materials, exposure to radiation is necessary to charge the sign. The charging step can be carried out during storage, after obtaining the sign but before applying it to a surface, and / or during or after application. It is appreciated that a charging time of at least a few minutes is generally required, so some charging time before or after application is probably desirable. In some embodiments using chemiluminescent materials, simply applying the luminescent emergency exit sign to a surface may be sufficient to activate the material, particularly if the sign is to be adhered to a surface whose shape differs from that of the chemiluminescent sign when stored. Pushing, pressing, or bending the sign into position can provide sufficient deformation to cause the sign to glow. Therefore, the activation step can be performed before, during, and / or after application to a surface. The specific order of steps shown in the processes is therefore not intended to be limiting. The procedure may include, in response to the failure of an electrical emergency exit sign: obtaining a photoluminescent emergency exit sign from the storage, the photoluminescent emergency exit sign including a adhesive layer arranged to allow the exit sign to adhere photoluminescent relief to a surface; the charge of the photoluminescent emergency exit sign by exposing it to the light; and the application of the photoluminescent emergency exit sign on a surface near the faulty electrical emergency exit sign so that the adhesive layer holds it in place as a sign replacement emergency exit. Alternatively or in addition, the procedure may include, in response to the failure of an electrical emergency exit sign: obtaining a chemiluminescent emergency exit sign from the storage, the chemiluminescent emergency exit sign including a adhesive layer arranged to allow the exit sign to adhere chemiluminescent relief to a surface: the activation of the chemiluminescent emergency exit sign in the distorting; and the application of the chemiluminescent emergency exit sign on a surface near the faulty electrical emergency exit sign so that the adhesive layer holds it in place as a sign replacement emergency exit. The process may also include removing a cover or packaging from the chemiluminescent emergency exit sign. Some chemiluminescent materials can degrade upon exposure to ultraviolet (UV) radiation and may therefore be stored in a sealed package (e.g., aluminum foil) or other container that is at least substantially opaque before use, and / or a peel-off surface cover may be provided. A third aspect proposes a method for maintaining the airworthiness of a passenger aircraft in the event of a failure of an electrical emergency exit sign, so that the aircraft can be returned to a service point. The method comprises: obtaining a luminous emergency exit sign from the storage, the luminescent emergency exit sign comprising a layer adhesive arranged to allow the exit sign to adhere luminescent relief to a surface; the activation and / or charging of the luminescent emergency exit sign; the application of the luminescent emergency exit sign on a surface to proximity of the faulty electrical emergency exit sign so that the adhesive layer holds it in place as an exit sign replacement service; the completion of a scheduled flight of the aircraft using the exit sign of luminous emergency sign as a required exit sign; and aircraft maintenance to repair or replace the exit sign faulty electrical backup before the aircraft's next flight. The process may include: obtaining a photoluminescent emergency exit sign from the storage, the photoluminescent emergency exit sign including a adhesive layer arranged to allow the exit sign to adhere photoluminescent relief to a surface; the charge of the photoluminescent emergency exit sign by exposing it to light; the application of the photoluminescent emergency exit sign on a surface near the faulty electrical emergency exit sign so that the adhesive layer holds it in place as a sign alternative solution; the completion of the aircraft's scheduled flight using the exit sign photoluminescent emergency lighting as a required exit sign; and aircraft maintenance to repair or replace the exit sign faulty electrical backup before the aircraft's next flight. In addition, or alternatively, the process may include: obtaining a chemiluminescent emergency exit sign from the storage, the chemiluminescent emergency exit sign including a adhesive layer arranged to allow the exit sign to adhere chemiluminescent relief to a surface: the activation of the chemiluminescent emergency exit sign in the distorting; the application of the chemiluminescent emergency exit sign on a surface near the faulty electrical emergency exit sign so that the adhesive layer holds it in place as a sign replacement emergency exit; the completion of a scheduled flight of the aircraft using the exit sign of chemiluminescent emergency lighting as a required exit sign; and aircraft maintenance to repair or replace the exit sign faulty electrical backup before the aircraft's next flight. In the second or third approach, the adhesive layer of the luminescent emergency exit sign can be applied over a damaged area of ​​the electrical emergency exit sign. The luminescent emergency exit sign can be sized and positioned so that the electrical emergency exit sign is completely covered. The approach may therefore involve covering the electrical emergency exit sign. This can help avoid confusion caused by multiple signs and / or reduce visual clutter compared to a single, redundant sign. The process may also include detaching the luminous emergency exit sign from the defective electrical emergency exit sign prior to maintenance. The load on the photoluminescent emergency exit sign may include maintaining the photoluminescent emergency exit sign adjacent to a source of light before positioning it as a replacement emergency exit sign. According to a fourth aspect, a temporary luminescent exit sign is proposed for use as part of an aircraft cabin lighting system when an electrically illuminated exit sign is defective. The luminescent sign is portable and includes an adhesive layer arranged to allow the luminescent emergency exit sign to adhere to a surface. The sign is arranged to adhere to a surface near an electrically illuminated emergency exit sign in the aircraft cabin during operation. The sign includes one or more exit identifiers. At least one exit identifier may be or include a word (e.g., "EXIT") or a symbol (e.g., a running person and / or an arrow). The luminescence of the sign is arranged to make the exit identifier(s) visible in low-light or dark conditions. The issue identifier(s) can be: (1) formed by shaping the luminescent material of the sign; and / or (ii) formed by masking a portion of the luminescent material of the sign (for example, when the luminescent material is supplied in a layer (regular on the sign). The sign is not electrically powered, but relies on luminescent processes within the sign. A non-electric, luminescent glow is therefore provided. The sign can be photoluminescent and / or chemiluminescent. The sign of the fourth aspect can be used as part of the apparatus of the first aspect, and / or in the processes of the second and third aspects. The sign can be flexible so that it can conform to the surface to which it is attached, for example by bending around the corners of a device or light fixture, or by adapting to a curved wall shape. The embodiments of the invention therefore allow for a temporary exit signaling that does not need to be connected to an aircraft power supply. Current emergency exit systems often include a hybrid photoluminescent (PL) and electric system, with PL floor markings and electric exit signs at both the lower and upper levels. The floor signs face upwards, towards the car lights, and are generally uncovered except when people are passing in front of them, which facilitates the charging of the PL material by the car lights during normal operation. In contrast, the lower-level exit signs are typically located on a car wall, facing inwards and towards the interior. Low height (often below seat level). These low-level exit signs were previously considered unsuitable for replacement with PL signs, as their placement was often obscured during use. The present invention overcomes this harm in the art by presenting the concept of a portable, self-adhesive, photoluminescent emergency exit sign for temporary use. Furthermore, the use of chemiluminescence in aircraft emergency systems is currently unknown, at least in part because the maximum durations of sufficient glow are likely to be less than 8-12 hours, after which the sign would be "worn out" and would have to be discarded (or chemically treated at great expense to return to the original materials). Therefore, there is harm in the art against the use of chemiluminescent materials for aircraft exit signs. The embodiments of the invention therefore make it possible to use a temporary luminescent EXIT identifier sign at a low level, the upper edge of which can be placed less than 122 cm (48 inches) from the floor of the aircraft cabin. The embodiments of the invention also allow the use of temporary luminescent EXIT identification signs at a high level. The embodiments of the invention therefore provide a luminous "EXIT" sign (for example chemiluminescent and / or photoluminescent) which can be kept on board the aircraft (for example in a crew kit) and can be installed by a crew member without requiring expertise or technical training, in order to allow the aircraft to complete its flight. Installing the luminescent sign directly over the (defective) electrical sign, so that the defective sign is covered, can provide positioning guidance to the installer and avoid confusion due to the presence of multiple signs visible for the same exit. Those skilled in the art will understand that the features described for one aspect of the invention can be applied, mutatis mutandis, to the other aspect of the invention. BRIEF DESCRIPTION OF THE FIGURES The following, by way of example only, is a detailed description of embodiments of the present invention with reference to the accompanying drawings, in which: Figure 1 is a schematic view of a photoluminescent exit sign. at a low level in accordance with various embodiments of the invention; Figure 2 (earlier art) gives examples of three exit signs electrical systems at a low level of prior art, demonstrating their positioning general and their dimensions; Figure 3 is a schematic view of an aircraft cabin, comprising a aircraft cabin lighting system according to an embodiment; Figure 4 is a schematic view of an aircraft cabin light fixture. which has mounted a luminous sign inside an aircraft cabin; And Figure 5 is a schematic view of an aircraft in which modes of re- implementation of the invention can be put into practice; Figure 6 illustrates processes for various modes of implementation; and Figure 7 is a schematic view of a chemiluminescent exit sign. in accordance with various embodiments of the invention. DETAILED DESCRIPTION In the figures, similar reference numbers are used for similar or corresponding features. As best illustrated in [Fig. 1], a luminescent emergency exit sign 1 is proposed for use as part of an aircraft cabin lighting system. The luminescent emergency exit sign 1 shown in [Fig. 1] is a photoluminescent emergency exit sign, but it is appreciated that most of the features described with respect to this embodiment can also be applied to signs exhibiting other forms of luminescence. The photoluminescent emergency exit sign 1 of [Fig. 1] comprises a plurality of layers. The sign 1 includes a base layer 2. The base layer 2 comprises a photoluminescent material 4, and can therefore be called the photoluminescent layer 2. The photoluminescent material 4 may be present uniformly on the base layer 2, or only in selected regions in various embodiments. In the embodiment shown, the photoluminescent material 4 is present uniformly on the base layer 2. The photoluminescent material 4 is arranged to be charged by electromagnetic wavelengths in a first range and to emit electromagnetic emissions in a second range. In the embodiment shown in [Fig. 1], a marking layer 6 is provided above the photoluminescent layer 2. In the embodiment shown, this layer is located adjacent to the base photoluminescent layer 2. The marking layer 6 includes informative text or symbology 8, such as the text "EXIT" and / or the image of a person running, which can be called an exit identifier. The text or symbology of the marking layer 6 can be provided in positive or negative form, as described in more detail below. In various embodiments, the marking layer 6 is made to This creates variations in transparency on the surface of the sign 1, so that the glow of the photoluminescent material is visible in some areas but not in others. In some embodiments, the marking layer 6 may be completely opaque and may be provided in one or more discrete areas as opposed to a single continuous layer with varying transparency on the sign 1, so that the photoluminescence is visible only in those areas of the sign 1 not covered by the marking layer. The marking layer 6 may vary in color / may have a different color from the base layer 2 in embodiments where the base layer 2 is visible, so that the exit identifier is visible under normal lighting conditions without depending on the luminescence. It will be appreciated if the marking layer 6 can be shaped differently from the base layer 2 and may not extend over the entire base layer. For example, the marking layer 6 may be provided by ink printed on the base layer 2 in the form of an issue identifier, or may in fact consist of the base layer 2 itself. The ink, which may be UV-curable, is made to adhere to the base layer 2 and lies on top of it. The ink constitutes the marking layer 6 in these embodiments. The ink can be chosen to coat the base layer 2 rather than impregnate it, resulting in a separate layer covering a portion of the base layer 2 and increasing the thickness of the luminescent emergency exit sign 1. The marking layer 6 can comprise multiple discrete parts - for example, separate, non-contiguous, and conformed regions, each forming a single letter of an exit identifier. In some embodiments, a protective layer 10 is provided above the marking layer 6, on one side of the marking layer 6 away from the photoluminescent base layer 2. The protective layer 10 is at least semi-transparent at the wavelengths of the first and second ranges. The protective layer 10 can protect the marking layer and the photoluminescent material from damage and can be waterproof. The protective layer 10 can be a thin transparent film. An adhesive layer 14 can be provided for adhering the protective layer 10 to the marking layer 6. The adhesive 14 can be provided as part of the protective layer 10, the marking layer 6, or separately. In some embodiments, the adhesive 14 can be provided in one or more discrete areas rather than as a uniform layer on the sign 1, or another method of applying a protective layer can be used.In some alternative embodiments, a protective layer may not be provided. It is desirable that the protective layer 10 and the adhesive layer 14 are all Two transparent, or at least partially transparent, layers at the wavelengths of the first and second ranges. The first range allows wavelengths absorbed by the photoluminescent material to charge the photoluminescent materials. The second range allows emitted wavelengths to pass through the protective layer, enabling a passenger to see the photoluminescence. In variant embodiments, there may not be a separate marking layer 6. Instead, the layer 2 comprising the photoluminescent material 4 may itself provide one or more inscriptions (e.g., text, symbols, or images) to provide an exit identifier. The image or text may be provided by distributing the photoluminescent material 4 over the base layer 2. The base layer 2 may also be colored accordingly, optionally to allow the same inscriptions to be visible when the sign 1 is well illuminated to the point that the photoluminescence is not noticeably visible (which is common under normal lighting conditions). In such embodiments, any protective layer 10 present may be located directly above the base layer 2 (optionally with an intermediate adhesive layer 14). In embodiments where the sign is provided with a protective layer 10, it is desirable that the protective layer be arranged so as to substantially cover the entire inscription and any photoluminescent border attached to it, and to protect the sign from wear and tear. The protective layer may have a finish chosen from matte, glossy, or anti-reflective. The base layer 2 of the embodiment shown in Fig. 1 comprises a photoluminescent material 4. The photoluminescent material 4 may be provided on a substrate 12. In some embodiments, the photoluminescent material 4 may be supplied as a suspension of photoluminescent pigments in a resin. The underside of the base layer 2 may be described as forming a back face of the sign 1, with the informational text or symbology being visible from the front. An adhesive layer 3 is provided on the underside of the sign 1; the adhesive layer 3 may be, for example, an adhesive spread over the base layer 2, or a separate layer applied over it. The adhesive layer 3 may be applied over or be part of the base layer 2, or there may be one or more intermediate layers. The adhesive layer(s) 3, 14 may comprise any suitable adhesive known in the art. Different adhesives may be used for different adhesive layers 3, 14 of the same sign 1. The separation of layers 2, 3 shown in [Fig.1] and the absence of intermediate layers are shown as an example only and are not intended to be limiting. In various embodiments, the adhesive layer 3 may be or include: (i) an even layer of adhesive material spread on the underside of sign number 1; or (ii) one or more separate adhesive areas, or patches, on the underside of sign number 1. The adhesive layer 3 is therefore optionally a continuous layer extending over the entire surface of the sign 1, but it may include a plurality of discontinuous adhesive areas, or a single adhesive area smaller than the sign 1, in other embodiments. A peelable backing layer (not shown) on the underside of the sign 1 may also be provided in some embodiments to protect the adhesive layer 3 before use or to prevent the sign 1 from unintentionally sticking to something. Similarly, the peelable backing layer may be a single piece, optionally extending over the entire surface of the sign 1, or may comprise multiple sections, or be a single shaped piece covering part or all of the surface of the sign 1. The backing layer may generally be arranged to cover the entire adhesive, regardless of its arrangement, and may be made of paper (optionally coated paper). The luminescent sign 1 is designed to be glued or made to adhere to an object or surface by means of the adhesive layer 3. The luminescent sign 1 can therefore be described as a decal.In some embodiments, the adhesive layer 3 is arranged to be detachable from the surface to which it is applied, so that the luminescent emergency exit sign can be temporarily installed and then subsequently removed without damaging the sign 1 or the surface, for example, by peeling off the sign 1. The adhesive layer 3 can be arranged to peel off, and the sign 1 can be immediately reused (after being recharged, if necessary). However, in some cases, it may be desirable to avoid signs that can be peeled off in case of damage by passengers—a more permanent adhesive material can be used in such cases. A solvent can be used to remove the photoluminescent sign 1 once it is no longer needed in this case, or the sign can be peeled off or torn from a surface and a solvent can be used to remove any adhesive remaining on the surface.If the sign is not damaged, a new layer of adhesive can be applied to allow its reuse in such embodiments. Alternatively, or in addition, a luminaire 26 to which it is attached can simply be replaced in certain scenarios. The marking layer 6 of the embodiment shown in [Fig. 1] is intended adjacent to the photoluminescent base layer 2. The marking layer 6 may be a film. Alternatively, the marking layer 6 may be printed directly onto the photoluminescent layer or onto an underside of the protective layer 10. The marking layer 6 may be printed using UV-curing ink. The marking layer 6 may, for example, be formed by digital printing or solvent-based screen printing. The marking layer 6 is desirablely at least partially opaque to electromagnetic emissions in the second range (the range emitted by the luminescent material). Preferably, the marking layer should be substantially opaque to electromagnetic emissions in the second range, at least in some parts. In some embodiments, the marking layer may include a colored film, such as a black film.In some embodiments, the marking layer may include a film, transparent or colored, onto which dark or black ink has been printed. The marking layer 6 may include symbology or words in positive or negative form. In preferred embodiments, the symbol or words may be printed onto a film, or more preferably in other embodiments, printed directly onto the photoluminescent layer 2. The symbology or words may be a term such as EXIT, arrows to indicate direction, or other symbols such as the image of a person running. When the symbology or words 8 are provided in positive form in the marking layer 6 (and thus in negative form for the luminescent glow), the desired words or symbology may be printed onto the marking layer 6.The printed portion 8 of the marking layer is chosen to block the transmission of light emitted by the photoluminescent material. In the final product, the symbology or term will appear as a dark area on a bright background in the sign in a low-light scenario. In some embodiments, the marking layer may include green, black, or red printing on a film. It will be appreciated that the red, black, or green text for "EXIT" is commonly used and therefore familiar to passengers, and that green printing is common for images of people running for exits. The printing may be the term or the symbology. The printing may be a layer with the words or symbology in negative (so that the exit identifier is visible in positive form with the luminescent glow).The print color or the color of the other marking layer can therefore be chosen to provide a familiar visual sign when the photoluminescent sign 1 is well illuminated, so that its photoluminescent glow is negligible (i.e., the luminescence may not be perceptible under normal lighting conditions), and to conform the visible photoluminescent glow when the sign 1 is less well illuminated. When the symbology or words are provided in negative form in the marking layer 6, the symbology or term 8 will appear as a bright area on a dark background in the emergency sign 1 in a low-light scenario. In some embodiments, printing may be done in an opaque material on a surface of the marking layer, with the unprinted areas of the layer forming the words or symbology. In other arrangements, the words or symbology may be formed by one or more cutouts in an opaque film. The words or symbology may be provided by an opening in the film or, in another embodiment, by a portion of the layer where there is no printing on the photoluminescent material. The marking layer 6 can therefore provide information arranged to be visible in well-lit conditions - for example, standard information, printed in black and white or in color, arranged to be visible without requiring photoluminescence, simply in the cabin lighting if / when the cabin is well lit. In embodiments with a marking layer, it is desirable that the marking layer 6 be transparent or at least partially transparent to wavelengths in the first and second ranges in all regions where photoluminescence is intended to be visible. Transparency in the first range allows wavelengths absorbed by the photoluminescent materials to reach and charge them. Transparency in the second range allows emitted wavelengths to pass through the relevant portion(s) of the marking layer in order to reach an observer. The photoluminescent material 4 of the base layer 2 exhibits persistent luminescence. The photoluminescent layer 2 can be configured to emit blue or green light. Typically, the photoluminescent material comprises strontium aluminate. In a preferred embodiment, the photoluminescent material may be selected from Sr4Al4O25Eu, Dy, which emits in the blue region, and SrAl2O4Eu, Dy, which emits in the green region. The photoluminescent material is excited, or charged, by electromagnetic wavelengths in the first range. The excitation wavelengths in the first range may be from 250 nm to 470 nm. In some embodiments, the photoluminescent material emits electromagnetic wavelengths in the range of 400 to 800 nm. The second range may be from 400 nm to 600 nm or from 450 nm to 500 nm. The photoluminescent material may emit wavelengths in the second range that are blue and may be approximately 490 nm. In other embodiments, the second range may be from 450 nm to 700 nm or from 500 nm to 600 nm, or more preferably 500 nm. at 550 nm. In some embodiments, the photoluminescent material can emit wavelengths in the second range which are green and can be arranged to be around 520 nm. It is important to note that, provided the photoluminescent material is charged, in a low-light scenario, the light emitted by the photoluminescent material will pass through at least a portion of the marking and / or protective layer, and the emergency signaling or symbols will be visible to the aircraft's passengers and crew. Typically, a low-light scenario is one in which the aircraft's normal electrical lighting is faulty and the cabin is dark. It is desirable that the emitted light be within the range to which the human eye is sensitive in scotopic vision. The level or intensity of light output from the photoluminescent material may then be lower than what would be required if the output light were in a different wavelength range. In a normal lighting scenario, ambient light is reflected by the sign, which can display information similar to that shown by photoluminescence under lower lighting conditions (for example, due to printing on, or being part of, a marking layer 6, or the coloring of the base layer 2 itself). The emissions from the photoluminescent material are relatively much weaker than the reflected light and are generally not perceived by passengers or crew under normal lighting conditions. Therefore, the sign 1 can provide information (which may or may not be the same) under two different lighting conditions. It will be appreciated if, for emergency exit signs, the same information is generally arranged to be displayed in both lighting scenarios.However, in some cases, there may be differences, such as additional information visible under normal lighting. For example, information printed on the marking layer 6, visible under normal lighting conditions, may indicate that an exit 28 is an emergency exit and also provide text instructions to passengers seated in the emergency exit row (e.g., regarding bag placement). In contrast, photoluminescence can optionally be arranged to show less and / or simpler information, for example, simply indicating "EXIT," possibly accompanied by an arrow. In other examples, the information provided may be equivalent in both lighting scenarios. The photoluminescent emergency exit sign 1 of various embodiments therefore includes an exit identifier arranged to be illuminated (i.e., made visible or made more visible) in low-light conditions by a glow Photoluminescence originates from the photoluminescent layer. It should be noted that, depending on light levels and print contrast, the exit identifier may be visible in low-light conditions even without photoluminescence, but photoluminescence can improve its visibility. Therefore, photoluminescence can increase its visibility. The exit identifier can include one or more words and / or symbols that are formed by conforming the photoluminescent layer, either positively (so that the exit identifier—for example, the word "EXIT" or a person running—appears luminous) or negatively (so that the exit identifier—for example, the word "EXIT" or a person running—appears as dark letters against a luminous background). The distribution of the photoluminescent material 4 in the base layer 2 can therefore be arranged so that the inscriptions, or a mask for the inscriptions, are formed by the positioning of the photoluminescent material. Alternatively, or in addition, the exit identifier may include one or more words and / or symbols formed by masking a portion of the photoluminescent layer, for example, using a marking layer 6 as described above. The mask may form the inscriptions, so that the exit identifier—for example, the word "EXIT"—appears in dark letters against a bright background, the exit identifier being formed by a mask on the photoluminescent layer, or the mask may provide a negative of the inscriptions so that the inscriptions are luminous. In such examples, the distribution of the photoluminescent material 4 in the base layer 2 may be regular across the base layer. Dark areas can therefore be formed by masking parts of a photoluminescent layer that is optionally uniform, or by gaps in the photoluminescent material. Bright areas can therefore be formed by not covering selected regions of a photoluminescent layer that is optionally uniform, or by shaping / positioning the photoluminescent material appropriately within the base layer. The issue identifier can therefore be shown in positive or negative form, but in both cases it is shown in a photoluminescent manner. Figure 7 illustrates a luminescent sign 1 of another embodiment. The luminescent sign 1 of Figure 7 is chemiluminescent and not photoluminescent. The same reference numbers are used for the base layer 2, the marking layer 6, the adhesive layer 3, and the lettering 8, all of which perform the same functions as those described above for the photoluminescent embodiments. The photoluminescent material 4 of embodiment [Fig.1] is replaced by A chemiluminescent material 4a may be in the form of a liquid, a solution, or a suspension. The chemiluminescent material 4a may be formed from a mixture of two (or more) different substances. The mixture of these substances can initiate a chemiluminescent chemical reaction, thereby activating the chemiluminescent sign. The substances may be or include hydrogen peroxide, oxalate esters (e.g., trichlorosalicylate oxylate esters), and one or more dyes chosen to provide a desired color, or other suitable chemicals known in the art may be chosen. It will be appreciated that chemiluminescence may not begin until after activation, but that the presence of each of the unmixed components in an arrangement that allows them to mix upon activation provides a material capable of producing chemiluminescence.To facilitate description, the plurality of unmixed components is therefore also called "chemiluminous material". The chemiluminescent material 4a of embodiment [Fig. 7] is encapsulated and contained within a pouch or other container 5. The container or pouch 5 is arranged to be deformable, at least partially, to facilitate the activation of the chemiluminescent material 4a, and may be made of or include a flexible plastic material. A plurality of containers or pouches 5 may be used in some embodiments. A breakable bottle or other container (not shown) may be contained within container 5 and arranged to break when container 5 is deformed, so as to allow a component within the bottle to mix with a component outside the bottle, but still within container 5. Further deformation (e.g., by squeezing or massaging) of container 5 may help to ensure that the components are well mixed to provide a more even and / or stronger glow. The need for a container 5 for a liquid component 4a may lead to chemiluminescent signs 1 being thicker than their photoluminescent counterparts in some cases, but thicknesses of 4 mm, 3 mm, 2 mm, or 1.5 mm or less can still be achieved. The chemiluminescent sign 1 can therefore still be flexible enough to conform to the surface to which it is applied in many embodiments. A protective coating, if present, can add approximately 0.5 mm to the thickness of the sign compared to the same sign without a protective coating. A front surface of the sign 1 is likely to be the same for all types of luminescence – chosen to cover an electrical exit sign – as discussed in more detail below. In some embodiments, for example for larger chemiluminescent signs, a set of containers 5 may be supplied on a base layer 2. Separating the chemiluminescent material 4a into compartments smaller than the overall dimensions of the sign can facilitate regular mixing of the components during activation. In the embodiment shown, the base layer 2 is located behind the container 5; in other embodiments, a lower surface of the container may provide the base layer 2. The base layer 2 may be a flexible film or sheet, and may be opaque. In other embodiments, a rigid base layer 2 may be provided, for example in the form of a plate—a certain degree of deformability / flexibility of the container 5 is nevertheless generally provided to allow the activation of the material 4a it contains. In some embodiments, however, the container may be rigid and a separate moving part—for example, a screw or piston passing through a wall of the container—may be provided to allow the activation of the chemiluminescent material 4a.It will be appreciated that such a feature may entail additional costs and possibly an additional point of failure, but that it may be a viable alternative to deforming the container 5 for activation in certain embodiments – for example, impacts on the sign are expected and a ribbed protective layer 10 is provided. In some embodiments, a protective layer 10 can be applied after the activation of the sign 1, potentially allowing the material to be activated by deforming the container 5 before it is protected by a more rigid lid 10. In the embodiment shown, at least one upper surface of the container or pouch 5 is at least substantially transparent to radiation emitted by the chemiluminescent material 4a. In some embodiments, the entire container 5 may be transparent. In the embodiment shown, a marking layer 6, comprising for example letters or symbols printed on a film, is applied to the upper surface of the container 5 so as to provide an issue identifier, as for the marking layer 6 described above. For example, a film or another marking layer 6 can be laminated onto the container. In other embodiments, the issue identifier may be part of the upper layer of the container 5, a portion of the upper layer of the container 5 being at least substantially opaque to the wavelength range of chemiluminescence, and other portions being at least substantially transparent, such that bright and dark areas are formed. In other embodiments, an issue identifier may be printed on a top layer of the container 5. However, it will be appreciated that some chemiluminescent materials 4a are decomposed by UV light, and that the hard- UV curing of an ink printed on the container 5 may therefore be inappropriate. An ink not requiring UV curing may therefore be chosen in embodiments using an issue identifier printed on the container 5, or the container 5 may be printed before being filled with the chemiluminescent material 4a, or a mask may be applied around the issue identifier to allow it to cure under UV light without UV light reaching the chemiluminescent material 4a. In other embodiments, the container 5 can be shaped to form the inscriptions by controlling where the chemiluminescent material 4a is present—for example, pillars within the container can create solid regions without chemiluminescent material 4a, and / or the container 5 can take the form of a word or symbol. In these cases, the container 5 may comprise a set of individual containers—for example, one for each letter of a word or each separate part of a symbol—which may or may not be seamlessly connected. As with photoluminescent signs, a protective layer 10, optionally fixed by an adhesive layer 14, can also be used - applied directly to the container 5 or over the marking layer 6 if present. Regardless of the type of luminescent material used, it is recommended that sign 1 meet aerospace requirements. These include the DO-160 standard, which addresses environmental requirements such as the effects of temperature, altitude, humidity, impact and crush resistance, vibration, water and fluid sensitivity, flammability, etc. Signs must meet the flammability requirements of CS / FAR25.853. The sign's luminance must also meet the requirements of CS 25.812 and CS 23.2315 for large aircraft or CS 29.812 for large rotorcraft with respect to safety-critical signage, particularly when the signs are used for emergency exit signage. In small aircraft or rotorcraft, the sign may need to meet the requirements of CS 27.805 and CS 27.807. The luminescent emergency exit sign 1, in various embodiments, is flexible so that it can adapt to the shape of the surface to which it is applied. The sign 1 can therefore adhere to a curved cabin wall 24, or to a flat wall section or a light fixture 26, and can bend around the corners of the surface to which it is applied. The sign 1 can be installed manually. The luminescent emergency exit sign 1 of various embodiments is dimensioned and shaped to cover an electrical emergency exit sign 26 when the adhesive layer is applied to the electrical emergency exit sign 26. It will be appreciated that the electrical emergency exit signs 26 of different aircraft 22 may have different dimensions, and that even within the same aircraft cabin 20, signs of different dimensions may be present, for example positioned near different emergency exits 28, or in different locations 26a, 26b within the cabin. The dimensions can therefore be chosen appropriately according to the electrical emergency exit sign 26 that the luminescent sign 1 is intended to replace. The luminescent emergency exit sign | may have a surface area (in particular, of the front face of the sign on which inscriptions are visible) of between 9 cm² and 400 cm², and optionally between 25 cm² and 400 cm², and optionally between 25 cm² and 50 cm². In some embodiments, the sign 1 may have a surface area of ​​approximately 40 cm². Sign 1 can be square or rectangular in shape, for example with dimensions of 3 cm by 3 cm, or 10 cm by 4 cm. Sign 1 can be much thinner in the third dimension, so that the sign is flat, and may be no thicker than a piece of card. In some embodiments, sign 1 can have a thickness ranging from 0.5 mm to 2 mm, and optionally from 0.5 mm to 1.5 mm. The photoluminescent layer of sign 1 can have a thickness of approximately 0.7 mm in some embodiments, and may constitute most of the sign's thickness. A protective layer, if present, can add approximately 0.5 mm to the thickness of the sign compared to the same sign without a protective layer. As illustrated in [Fig. 3], the luminescent sign(s) 1 are intended for use in the cabin 20 of an aircraft 22. [Fig. 3] illustrates a low-level sign 1a and a high-level sign 1b. The sign 1 can be adapted to be attached to a wall 24 in the cabin 20 or to be attached to a light fixture in the cabin 20 of the aircraft 22, such as to adhere to an electrically operated emergency exit sign 26 as shown in [Fig. 4]. In some embodiments, the sign 1 can be adapted to be attached to an emergency exit door 28 in the cabin 20 of the aircraft 22. It will be appreciated if the luminescent sign 1 is used to indicate the location of an emergency exit 28. In general, lower-level signs can indicate the immediate presence of an emergency exit, and upper-level signs can direct an observer to one or more emergency exits (for example, by being located spaced apart from an emergency exit and providing an arrow to such an exit) and / or indicate the immediate presence of an emergency exit (for example, by being located directly above an emergency exit door). Figure 5 is a schematic representation of an aircraft according to the invention. in which the location of the emergency exits 28 is indicated by the location of signs on the walls 24 of the cabin 20. The aircraft cabin lighting system includes one or more cabin lighting devices 26, each cabin lighting device 26 comprising an emergency exit sign arranged to be electrically illuminated. These are aircraft cabin lights 26 20, which are not intended to be removed between maintenance periods. If one or more bulbs in one of these electrical emergency exit signs 26 are defective, or if any other fault causes the electrical sign 26 to be defective, the aircraft 22 may be grounded (or not permitted to fly with passengers) until the fault is repaired, due to stringent safety standards. In the aircraft cabin lighting systems of the invention described herein, one or more luminescent signs 1 as described above are provided. Desirably, they are stored in a location known to the cabin crew, but not accessible to passengers. In the event of a failure of an electrical sign 26, a luminescent sign 1 can be retrieved, activated, and / or optionally charged if necessary, and then positioned appropriately to mark the exit 28 for which the electrical sign 26 is defective. In some cases, the sign 1 may be photoluminescent and sufficiently illuminated during storage to be already adequately charged upon retrieval, so that a deliberate charging step may not be required. The luminescent sign 1 can be affixed to a cabin wall 24 adjacent to the defective electrical sign 26, or it can be affixed to the defective electrical sign 26 itself, optionally completely covering the defective luminaire 26. In some scenarios, the luminous sign 1 can be made to adhere to the exit door itself 28, although it may no longer be visible inside the cabin once the door is opened, which is not desirable. The safety requirements for passenger and crew wayfinding are therefore met by providing the luminescent sign 1 in an emergency scenario, allowing the aircraft 22 to continue its planned flight. Furthermore, the aesthetic appearance of the cabin is not compromised by the intrusion of additional emergency signage during normal operation if the luminescent sign 1 covers the defective luminaire 26, while still fulfilling the safety requirements. Fig. 2 (prior art images) shows three examples of aircraft cabin emergency exits 28 with electric exit signs 26 - in particular, these cabins 20 each have a "low level" exit sign 26a and a high level exit sign 26b for each emergency exit door 28. High-level exit signs 26b are usually located on a wall 24 of the cabin 20, often near or adjacent to an upper side of the emergency exit door 28 - for example, located in the centre above the door 28, or located adjacent to or near an upper corner of the door 28. High-level exit signs 26b may also be provided further away from the exits, directing passengers towards the exits. Low-level exit signs 26a are typically located on a cabin wall 24 20, near or adjacent to a lower corner of the emergency exit door 28. Low-level exit signs are situated within 122 cm (48 inches) above an aircraft cabin floor 20, and generally within 50 cm or 30 cm above the floor. Low-level exit signs are usually part of, or associated with, emergency route markings on the floor, so that, in the event of an emergency with poor visibility (for example, due to smoke and / or failure of the main cabin lights), a passenger following the floor markings will be guided to an emergency exit 28 marked with such a sign 26a. The exit signs on lower level 26a are located below the top of the seats intended for passengers, and often (as shown in the central and right-hand examples of [Fig.2]) at or below seat level, so that they are at the same level as the bottom of the passenger's legs when seated. Low-level exit signs 26a are generally located on, or at least substantially parallel to, a cabin wall 24, facing into the cabin 20. Depending on the cabin configuration, and whether the bulbs or other cabin lights are switched on or not functioning (which can be described as the cabin's MMEL condition), this positioning may be at least substantially perpendicular to most cabin lights, which may be ceiling-mounted and directed downwards. These low-level exit signs 26a may therefore not be adequately illuminated by the cabin lighting, as the light may be blocked by passengers, seats, seatback trays, and other objects, and furthermore, the signs may not be facing the cabin lights. The light level (Lux) may therefore be too low for the photoluminescent materials to be charged in these locations under certain scenarios, due to the cabin lighting being blocked or not switched on and / or the location being in shadow.High-level exit signs may present some of these problems, depending on cabin lighting arrangements. Electric luminaires 26a are used due to prejudice against the use of photoluminescence for emergency exit signs 28 (in contrast, floor markings along aisles may be much less likely to be continuously obstructed / obscured during a flight, and face upwards in . direction of cabin lights, and photoluminescent floor markings are known). Various 600 methods of embodiments of the invention are illustrated in [Fig.6]. A method 600 for providing emergency exit lighting in an aircraft cabin 20 includes, in response to the failure of an electrical emergency exit sign 26, obtaining 602 a luminescent emergency exit sign 1 from storage. The luminescent emergency exit sign | can be obtained from a storage location within the aircraft 22, and optionally within the aircraft cabin 20. Alternatively, the luminescent emergency exit sign 1 can be made available at an airport or other facility and retrieved as required. Preferably, an aircraft 22 can carry a plurality of luminescent emergency exit signs 1 as described herein, adapted to its electrical emergency exit signs 26 and / or other features of its aircraft cabin lighting system – for example, the signs 1 can be sized and shaped to fit well with, or be adjacent to, the electrical emergency exit signs 26, and / or to match in color with floor markings. Each luminous emergency exit sign | includes an adhesive layer 3 arranged to allow the luminous emergency exit sign 1 to adhere to a surface, such as a cabin wall 24 or an electrical emergency exit sign 26 (defective). For photoluminescent signs 1, process 600 further includes the charge 604a of the photoluminescent emergency exit sign | by exposing it to light. In some embodiments, the photoluminescent emergency exit sign 1 can be stored in a well-lit location so that charging is completed before the sign 1 is retrieved 602. In other embodiments, particularly those where the photoluminescent emergency exit signs 1 are stored within the cabin 20, the signs 1 may be in a cabinet, pouch, package or similar, and the photoluminescent material they contain may not be charged at all, let alone fully charged, when they are retrieved 602. Charging 604a can therefore be carried out before and / or after obtaining 602 the photoluminescent emergency exit sign |. Conveniently, having a photoluminescent emergency exit sign 1 that is easily portable allows the sign 1 to be charged in many ways — for example, on a sunny day, it can be positioned outside in direct sunlight to charge faster than with the cabin lighting, or if the pro- If airport or runway lights, spotlights, or other lighting are illuminated, the sign can be positioned facing such a light. Even if limited to the lights available in an aircraft cabin, the sign can be positioned directly in front of a cabin light. The weight and dimensions of the sign can be such that it can easily be held in the desired load position by hand, or with adhesive tape, adhesive putty (e.g., Blu-Tack®), or similar, or simply supported if necessary. In some embodiments, the cabin lighting may be sufficient to charge the photoluminescent sign 1. In some embodiments, the aircraft cabin lighting system may further include a dedicated charging light, arranged to be used to charge the photoluminescent emergency exit sign 1. Such a light may be stored with one or more photoluminescent emergency exit signs 1, and may be or include a torch or a lamp. Such a dedicated charging light can be arranged to provide light with wavelengths in a range chosen to be best absorbed by the photoluminescent material, in order to ensure charging efficiency. For example, the charging light can provide light with one or more wavelengths in the range of 350 nm to 500 nm, 400 to 500 nm, or 365 to 450 nm. The charging light can provide blue and / or UV light. It will be appreciated that aircraft cabin lighting may not contain much blue light (warmer colors are often preferred) and that UV light may be blocked or absorbed by cabin light covers. A dedicated charging light providing light in a targeted wavelength range can therefore provide a much more efficient charge for the photoluminescent sign 1, even at the same brightness / lux level. Similarly, moving the sign 1 outdoors to charge it in daylight can provide a broader charging spectrum, including more light of the desired wavelengths. A minimum Lux value of 500 to 1000 Lux may be desired for fast charging. In some cases, charging of sign 1 can be completed in five minutes. It should be noted that the intensity and wavelength range of available light will influence the charging time of a given photoluminescent sign 1. Different photoluminescent materials may also take longer to charge and / or charge more efficiently from different wavelength ranges. Typical charging times can range from 5 to 45 minutes. In various embodiments, the charging of sign 1 can be completed after 1 hour, 45 minutes, 30 minutes, 15 minutes, 10 minutes, 5 minutes, or 2 minutes of exposure of sign 1 to a light source. Any delay in the lifting of aircraft 22 can therefore be minimal and extremely reduced compared to the time required to bring aircraft 22 back into a maintenance bay, or to locate and call an engineer and the correct parts for the faulty electrical sign 26. In embodiments using chemiluminescent signs 1, the charging step 604a can be replaced by an activation step 604b. In the production step 602 or activation step 604b, the chemiluminescent sign 1, or the material container 5 for a chemiluminescent sign 1, may be removed from opaque packaging (e.g., a sealed foil or an opaque plastic pouch). This packaging may protect the chemiluminescent material 4a from degradation due to UV light. In some embodiments, a parts kit including a container of material 5 and a separate marking layer 6 to be applied to the container 5 may be provided. In other embodiments, the sign 1 may be supplied pre-assembled, and optionally there may be no separate marking layer, the egress lettering instead being incorporated into the container 5 using any of the techniques mentioned above. A preparation step consisting of applying a marking layer 6, and optionally also a protective layer 10, in order to assemble the sign 1 may therefore also be carried out. Activation 604b may involve deforming the sign 1, and more specifically the container 5, so as to mix two or more components within the container 5 and trigger chemiluminescence. The container 5 may be bent, pressed, twisted, massaged, and / or otherwise deformed so as to mix the components. This deformation may rupture, crush, or break a barrier or sub-container within the container 5, thereby allowing the components to mix. Alternatively or in addition, activation 604b may include the movement of a movable component of the container 5 - for example a screw, lever or plunger - so as to break, crush or otherwise shatter a barrier or sub-container within the container 5, thereby allowing the components to mix, without deforming a (possibly rigid) wall of the container 5. Activation 604b can take a few seconds, or even less than a second. In some embodiments, the forces applied to the container 5 / to the sign 1 when it is removed from the packaging and / or adhered to a surface may be sufficient to activate the material - the activation step 604b may therefore not necessarily be separated from the other steps of the process. In embodiments where both photoluminescent material 4 and chemiluminescent material 4a are present, both charging 604a and activation 604b can be performed. Preferably, the charging step 604a (generally longer) can be performed at least substantially before the activation step 604b. in some cases, in order to maximize the useful life of the chemiluminescent glow. A different charging and / or activation step 604 may be provided for different kinds of luminescence—for example, diluting a saline solution with water to reduce salinity may force bioluminescent algae to produce a glow, so adding water to a container could be used as an activation step 604b. The charging and activation steps 604 described here are therefore provided as examples only and are not intended to be limiting. The method 600 further comprises applying 606 the luminescent emergency exit sign 1 to a surface near the defective electrical emergency exit sign 26a, so that the adhesive layer 3 holds the luminescent emergency exit sign in place as a replacement emergency exit sign. The surface can be a wall of the cabin 24, or indeed a surface of the defective electrical emergency exit sign 26a. The application 606 of the luminescent emergency exit sign 1 to the surface may include peeling off or otherwise removing a protective / covering layer over the adhesive material 3 and pressing the sign 1 into position. The adhesive layer 3 of the luminescent emergency exit sign | can be applied 606 to a surface of the defective electrical emergency exit sign 26a. The electrical emergency exit sign 26a can therefore be partially or completely covered by the luminescent emergency exit sign 1. Advantageously, this can prevent any confusion between two visible exit signs (under normal lighting conditions) if the luminescent emergency exit sign 1 were placed adjacent to or near the defective electrical emergency exit sign 26. In embodiments using photoluminescence, the charge 604a of the photoluminescent emergency exit sign 1 may include holding the photoluminescent emergency exit sign 1 adjacent to a light source before positioning it 606 as a replacement emergency exit sign in some cases, but the charge 604a may be carried out after the photoluminescent emergency exit sign 1 has been applied 606 to the surface in other examples - to facilitate and accelerate the charge, a portable light source such as a torch may be used to provide more light for the charge than would otherwise be available within the cabin 20. This may be of particular importance for low-level emergency exit signs, or for high-level emergency exit signs in veiled positions. In embodiments of method 600 using a dedicated charging light, the dedicated light can be used to charge the photoluminescent emergency exit sign before it is adhered to the surface, or after it has been adhered to the surface. The dedicated charging light can be moved and positioned as needed. The 600 procedure can therefore allow an aircraft 22 to be “repaired” to meet the safety standards relating to the number of emergency signs within a relatively short period, without requiring highly skilled technical personnel, and / or without needing to return the aircraft to a service point. Aircraft 22 can therefore be authorized to complete its scheduled flight, with little or no delay to the scheduled departure time (depending on how quickly the defect is detected and the charging time of the photoluminescent sign 1). Method 600 for providing emergency exit lighting in an aircraft cabin 20 can be part of a method for maintaining the airworthiness of a passenger aircraft 22 in the event of a failure of an electrical emergency exit sign 26, so that the aircraft 22 can be returned to a service point. Method 600 can therefore include completing 608 a planned flight of the aircraft 22 using the luminescent emergency exit sign 1 as the required exit sign, instead of a defective electrical exit sign. Procedure 600 may further include servicing aircraft 22 to repair or replace the defective electrical emergency exit sign 26 prior to the aircraft's next flight. The luminescent sign 1 as described here is generally used for a single flight (or perhaps two relatively short "hops" with a minimal stopover in between). The luminescent sign 1 is chosen to have a sufficient emission time / discharge profile to maintain luminance above the minimum required by standards for the duration of the flight, but its luminance may very well fall below this minimum shortly thereafter, particularly in scenarios where a photoluminescent sign is used in a hazy location, or when a flight / use period of more than 6 to 10 hours is required for a chemiluminescent sign.Due to the low light exposure during normal operation in certain sign positions, little or no charging of the photoluminescent material of a photoluminescent sign 1 may occur during normal aircraft operation for certain exit sign positions (unlike floor markings, which are generally well illuminated by cabin lighting, and thus recharged throughout a flight under normal conditions). The illuminated emergency exit sign 1 can be detached from the faulty electrical emergency exit sign 26 before being repaired. In some cases, the The adhesive layer 3 can be chosen so that the sign 1 peels off cleanly and can be reused (in the case of photoluminescence, generally without the need to treat the photoluminescent material). In other cases, the sign 1 may be designed for single use and not intended to be reusable.

Claims

Demands

1. Aircraft cabin lighting system comprising one or more curs cabin lighting units, each cabin lighting unit including an emergency exit sign designed to be illuminated electrically; and one or more illuminated emergency exit signs necentes, the luminescent emergency exit signs being each portable, including an adhesive layer arranged to allow make the luminescent emergency exit signs adhere to a surface, and being arranged to adhere to a surface proximity of the electrical emergency exit sign in use.

2. Aircraft cabin lighting system according to claim 1, in which the or each luminous emergency exit sign is at minus one of the following: (i) photoluminescent; and (ii) chemiluminescent.

3. Aircraft cabin lighting system according to claim 1 or the claim 2, wherein the emergency exit sign(s) "Electrical" is a low-level exit sign, and is optionally: (1) located adjacent to a lower corner of an emergency exit; and / or (ii) located less than 122 cm, and optionally less than 50 cm, above an aircraft cabin floor.

4. Aircraft cabin lighting system according to any one of the re- previous demands, in which the or each sign of issue of The luminous emergency light is flexible so that it can adapt to the shape of a surface on which it is applied.

5. Aircraft cabin lighting system according to any one of the re- previous demands, in which the or each sign of issue of The luminous emergency light is sized and shaped to cover the electrical emergency exit sign when the adhesive layer is applied to it.

6. Aircraft cabin lighting system according to any one of the re- previous demands, in which the adhesive layer is arranged so that it can be detached from the surface of the emergency exit sign electric, so that the emergency exit sign is luminous can be temporarily installed, then removed.

7. Aircraft cabin lighting system according to any one of the re- previous demands, in which the emergency exit sign read- minescent includes a luminescent layer and an identifier an exit arranged to be illuminated by the luminescent layer.

8. Aircraft cabin lighting system according to any one of the re- previous demands, in which the emergency exit sign read- minescent includes an issue identifier, and in which The issue identifier includes one or more words and / or symbols who are: (1) formed by conformation of the luminescent layer; or (ii) formed by masking part of the lumin- nescente.

9. Aircraft cabin lighting system according to any one of the re- previous demands, in which the emergency exit sign read- Minescente is a photoluminescent emergency exit sign, and is arranged so that it can be charged with the cabin light ambient.

10. Aircraft cabin lighting system according to any one of the re- previous demands, in which the emergency exit sign read- minescente is a photoluminescent emergency exit sign, and the The system also includes a dedicated charging light, arranged to be used to charge the photoluminescent emergency exit sign nescente.

11. Aircraft cabin lighting system according to any one of the re- sales 1 to 8, in which the illuminated emergency exit sign- nescente is a chemiluminescent emergency exit sign, and is arranged to be activated by deformation of the chemiluminescent layer nescente.

12. Method for providing emergency exit lighting in a cabin aircraft, including, in response to a failure of a sign electrical emergency exit, obtaining a luminous emergency exit sign at from the storage area, the luminous emergency exit sign including an adhesive layer arranged to allow the activation or charging of the illuminated emergency exit sign nescente; and the application of the luminescent emergency exit sign on an area near the emergency exit sign faulty electrical wiring, so that the adhesive layer maintains in place as an emergency exit sign of replacement.

13. Method for maintaining the airworthiness of a passenger aircraft in in the event of a failure of an electrical emergency exit sign that the aircraft can be returned to a service point, the process including: obtaining a luminous emergency exit sign at from the storage area, the luminous emergency exit sign including an adhesive layer arranged to allow attach the luminescent emergency exit sign to a surface : the activation or charging of the illuminated emergency exit sign nescente; the application of the luminescent emergency exit sign on an area near the emergency exit sign faulty electrical connection so that the adhesive layer maintains cn place cn as long as emergency exit sign of replacement ; the completion of a planned flight of the aircraft using the luminous emergency exit sign as a sign required outcome; and aircraft maintenance to repair or replace the sign faulty electrical emergency exit before the next aircraft flight.

14. A method according to claim 12 or claim 13, wherein The luminescent emergency exit sign is an exit sign photoluminescent emergency light, and in which the charge of the sign photoluminescent emergency exit lighting includes the exposure of The photoluminescent emergency exit sign.

15. A method according to claim 12 or claim 13, wherein The luminescent emergency exit sign is an exit sign chemiluminescent emergency lighting, and in which the activation of the sign chemiluminescent emergency exit includes the deformation of chemiluminescent emergency exit sign.

16. A method according to claim 14, wherein the charge of the sign photoluminescent emergency exit includes the maintenance of the photoluminescent emergency exit sign adjacent to a source of light before positioning it as an exit sign replacement backup.

17. A method according to any one of claims 12 to 16, wherein the adhesive layer of the luminescent emergency exit sign is applied to a surface of the electrical emergency exit sign defective, so that the electrical emergency exit sign is completely covered.

18. 18. A method according to any one of claims 12 to 17, in which process further includes the detachment of the sign illuminated emergency exit sign faulty electrical system before maintenance.