Aircraft marking and emergency lighting systems

Abstract

The present invention relates to aircraft markings and emergency lighting systems. A method of manufacturing an aircraft photoluminescent marking is disclosed, wherein a photoluminescent marking comprising at least a substrate is provided, the method comprising: i) providing an ink or coating suitable for curing with ultraviolet (UV) radiation; ii) printing one or more markings directly onto the substrate of the photoluminescent marking with the ink or coating; iii) wherein the markings comprise patterns, text, images, blocks or logos; iv) wherein the substrate is one of a photoluminescent material and a housing; and v) curing the ink or coating with UV radiation. Also disclosed is an aircraft photoluminescent marking comprising a substrate and a layer comprising ink or coating markings printed directly onto the substrate, the ink or coating being a composition cured by UV radiation.

Description

[0001] This application is a divisional application of the Chinese patent application with application number 202010227930.6, application date March 27, 2020, and invention name “Photoluminescent Marker System”. Technical Field

[0002] The present invention relates to an improved photoluminescent marker and an improved method of making a photoluminescent marker. Background Art

[0003] In a commercial aircraft emergency, guidance may be provided identifying routes to exits and exit markers. In addition, markers may be used to identify various parts of the aircraft cabin or equipment. The route from the passenger seats to the emergency exits is typically indicated by emergency path markers disposed on the floor of the aircraft cabin. Typically, the emergency path markers are located in the aisle area of ​​the aircraft cabin. The emergency path markers may be provided in the form of strips extending along one or both sides of the aisle.

[0004] Emergency exits may be marked by exit sign markers. In order to facilitate safe evacuation of the aircraft cabin in an emergency, emergency exit markers must be visible in darkness.

[0005] In addition, in some cases, it is desirable to provide markers at other locations in the aircraft cabin. It may be desirable that these markers be visible in darkness or at low light levels.

[0006] In order for a photoluminescent marker to be used as a safety marker system, the system must meet many requirements, and when the photoluminescent material is used in an emergency evacuation guidance system, the guidance material must comply with CS / FAR 25 (certification standard for large aircraft). Typically, the system can be tested by performing a natural evacuation in a worst-case aircraft and system. Natural evacuation testing is generally accepted as confirmation of single-aisle and dual-aisle approvals. All photoluminescent material performance tests for further new approvals are then performed by comparing the performance of the material used for the natural test (naivetest). The material used for the natural test can be used as a limit sample. The limit sample can use a "worst case" arrangement of materials and markers. If other materials can show performance characteristics better than the limit sample, the other materials can be approved without retesting.

[0007] In the testing of emergency evacuation systems, two situations are considered. In the first situation, it is considered that an emergency has occurred on the runway during taxiing or takeoff. The second situation is considered to be a situation where the passengers are sleeping in the dark after a night flight. In this case, the human eye is considered to be dark-adapted. In both situations, the cabin of the aircraft can be considered to have been filled with smoke.

[0008] Typically, photoluminescent materials absorb energy from light in a specific wavelength range of the electromagnetic spectrum. The energy of the wavelength excites electrons from ions in the crystal lattice to a higher energy level. In photoluminescent materials, electrons typically may lose some energy to other ions in the crystal lattice. The electrons may then move to a metastable state, where they may remain for a period of time. Thermal energy absorbed from the crystal lattice may, after a period of time, cause the electrons to move from the metastable state to the ground state and emit light at a longer wavelength than the excitation energy.

[0009] The marker may include a covering disposed on at least the top or outer surface of the photoluminescent material. The covering may be provided to protect the photoluminescent material from wear, chemical attack, abrasion, etc.

[0010] In some cases, the photoluminescent marker may be provided in a simple form wherein the photoluminescent material is perceived in ambient lighting as having a yellow / green color and the emission color is typically green. It may be desirable to change the perceived color of the photoluminescent marker in ambient lighting. In many cases, it has been considered desirable to change the perceived color of the photoluminescent marker under ambient lighting conditions so that the photoluminescent marker blends with the color of the surface to which the marker is mounted or supported. This may be particularly desirable where the photoluminescent marker is used as an emergency path route marker in the aisles of an aircraft. It is desirable that such a crossing route marker be unnoticeable and intrusive or disruptive under normal conditions, but that the crossing route marker be conspicuous at low light levels in emergency situations where passengers must rely on the emergency path route marker for guidance.

[0011] Typically, marker systems have been provided in which a photoluminescent material is disposed on a base or support and has a protective covering. In order to change the appearance of the emergency path marker in ambient light, it is typically necessary to print a color or pattern on a film and to attach the film to the photoluminescent material or to fix the film adjacent to the photoluminescent material on a support or within a covering. The film and photoluminescent material can be inserted into a housing that can be fixed to, for example, the floor of a cabin. It should be understood that the film must be handled with care when the film and photoluminescent material are inserted into the covering, otherwise the film may wrinkle or distort. In some cases, the photoluminescent material and the film can be laminated together and fixed within a housing or to a covering. Typically, the photoluminescent material comprises a rigid or semi-rigid material. The photoluminescent material can include a semi-rigid insert.

[0012] In some embodiments, a color or pattern can be printed directly on the photoluminescent material in order to change the perceived color of the photoluminescent material under ambient lighting conditions. Printing on the photoluminescent material is performed by means of screen printing on the photoluminescent material. Screen printing limits the size of the print area. In practice, it is difficult to print an image with a print area greater than 1 m.

[0013] Typically, the photoluminescent material comprises a photoluminescent pigment dispersed in a resin. The photoluminescent pigment is typically not water stable. It has been found that the photoluminescent pigment must be dispersed in a resin in order to stabilize the pigment for use in a marker system. Printing on resin has been found to be difficult. In some cases, it has been found possible to screen print using solvents, but as noted above, this method is limited and solvent inks are not durable and are easily damaged.

[0014] Typically, the photoluminescent marker may comprise a photoluminescent material in a housing or provided with a covering. As aircraft escape guidance markers are typically located on the floor of an aircraft cabin, the markers are susceptible to damage caused by foot traffic over the markers. The covering or housing may comprise a polycarbonate covering. It has been found that the durability of the polycarbonate covering may be enhanced by the application of a protective coating. Typically, the coating may be methyl methacrylate. It has been found that printing on the coating used to enhance the durability of the covering is particularly difficult.

[0015] What is needed is an improved method for changing the perceived color of the photoluminescent material of an aircraft photoluminescent marker in ambient light. Summary of the invention

[0016] According to a first aspect of the invention, there is provided a method of manufacturing a photoluminescent marker suitable for use in an aircraft, the method comprising printing one or more markings on a photoluminescent material, the marking comprising an ink or coating suitable for curing with ultraviolet (UV) radiation, wherein the marking comprises a pattern, text, image, block or logo, and wherein the cured ink or coating is flexible and is printed directly onto the photoluminescent material comprising a flexible substrate, or wherein the ink or coating is printed directly onto a flexible housing.

[0017] According to a first aspect of the present invention, there is provided a method of manufacturing an aircraft photoluminescent marker, wherein a photoluminescent marker comprising at least a substrate is provided, the method comprising:

[0018] i) providing an ink or coating suitable for curing with ultraviolet (UV) radiation;

[0019] ii) printing one or more marks directly onto the substrate of the photoluminescent marker using ink or paint;

[0020] iii) where the mark consists of a pattern, text, image, block or logo;

[0021] iv) wherein the substrate is one of a photoluminescent material and a housing; and

[0022] v) Curing of inks or coatings with UV radiation.

[0023] In a preferred embodiment, the cured ink or coating is flexible. The degree of flexibility of the cured ink or coating is discussed further below.

[0024] In one embodiment the photoluminescent material is flexible.Flexible photoluminescent materials are described in our co-pending UK application GB1911253.1 (published as GB2577177), the contents of which are incorporated herein by reference in their entirety.

[0025] In another embodiment, the housing is flexible. In some embodiments, both the housing and the photoluminescent material are flexible. The photoluminescent material or housing can be arranged to be flexible so that it can be bent to a radius of from 0.1 m to 1.0 m. The cured ink or coating can be arranged to be flexible enough so that it can be bent and flexed in a manner that does not break or twist.

[0026] The mark includes a pattern, text, image, square or logo. The square can be a colored square.

[0027] Indicia may be applied to the photoluminescent marker in order to change the perceived appearance of the photoluminescent marker under ambient light or in an emergency situation.

[0028] Typically, prior art solutions require that indicia be printed on a film disposed in the housing. In some prior art solutions, the film is provided as a composition with a photoluminescent material, or in other prior art solutions, the film may be disposed in or on the housing or on top of the photoluminescent material.

[0029] In prior art solutions, it is not considered desirable or possible to print directly onto the photoluminescent material or housing. In particular, it has been found that it is not possible to print onto a resin in which the photoluminescent pigment is dispersed. Typically, the housing is provided with a protective coating on the outside of the housing. It has also been found that it is not possible to print onto the protective coating. In prior art markers, it is necessary to print onto a film and place the printed film onto the photoluminescent material or into or onto the housing.

[0030] According to some embodiments of the present invention, the coating or ink is printed directly onto the photoluminescent material. A particular advantage is that a pattern or logo or other marking can be printed directly onto the photoluminescent material and no additional components such as films are required. It should be appreciated that removing components from the assembly of the final marker reduces the cost and complexity of the manufacturing process. It should also be appreciated that removing components from the assembly of the final marker is particularly important in the manufacture of aircraft markers because aircraft components are particularly sensitive to weight. For example, removing components from an escape marking system can reduce the overall weight of the aircraft system.

[0031] It is particularly desirable to be able to print a pattern directly onto the photoluminescent material so that the ambient light appearance of the photoluminescent marker matches the appearance of the surrounding area on which the photoluminescent marker is mounted. It may be desirable to change the perceived appearance of the photoluminescent material in ambient light so as to make the security feature of the photoluminescent material less intrusive or disruptive. An advantage of the manufacturing method is that the photoluminescent material can be inserted into the housing. The photoluminescent material can be provided as an insert comprising a base and the photoluminescent material. The insert can be arranged to comprise a single piece insert, rather than comprising a base and the photoluminescent material and a film. It will be appreciated that a single piece insert provides for easier manufacture and easier installation into an aircraft.

[0032] Printing directly onto the surface of a photoluminescent material has provided unexpected advantages in achieving a much wider range of daylight color choices and patterns than prior art solutions. Typically, the photoluminescent material comprises a photoluminescent pigment in a resin or polyurethane. It has been unexpectedly discovered that inks and coatings that can be cured with UV light can be printed directly onto the resin of the photoluminescent material. Once cured by UV light, the ink or coating is durable and flexible. The skilled person will appreciate that in some embodiments, the surface of the photoluminescent material may be hard and rough due to the particles of the photoluminescent pigment. It will also be understood that it is considered difficult to apply inks and pigments directly to the photoluminescent material, particularly if the particle size in the photoluminescent pigment is relatively large. If the pigment particle size is large, the photoluminescent pigment may have a brighter output, and the photoluminescent pigment may have a longer duration. However, it has been found that this increases the difficulty of screen printing on the photoluminescent material using prior art solutions. Unexpectedly, it has been found that inks or coatings can be printed directly onto the photoluminescent pigment, thereby providing a durable coating even on large particle sizes in the photoluminescent material.

[0033] Unexpectedly, it has been found that inks and coatings that can be cured with UV light can be printed directly onto a protective coating applied to the outside of the housing over the photoluminescent material. The ink or coating can apply a color or textured pattern to the outer surface of the housing.

[0034] Unexpectedly, it has been found that inks and coatings can be applied to photoluminescent materials and housings. The use of UV curable inks and coatings has enabled the development of new combinations and products.

[0035] For example, according to the present invention, a printed layer may be provided that extends from a first side edge to a second side edge of the marker.

[0036] In prior art solutions, the printed film is typically applied as a film on or over the photoluminescent material.Therefore, once the photoluminescent material is inserted into the housing, there are portions of the marker that do not have a pattern along either side of the marker.

[0037] An unexpected advantage of the present invention is that UV printing can be applied to both the photoluminescent material and the material of the housing. Thus, a pattern or color can be applied that extends from a first edge of the marker to a second edge of the marker.

[0038] Another unexpected advantage is that the surface does not need to be flat. It has been found that it is possible to print onto a curved surface. The marker may be considered to have a width X, a length Y, and a height Z. The surface may be bent in a transverse direction relative to the length of the marker (in the XZ plane). The surface may be bent or curled in a longitudinal direction relative to the length of the marker so that the bend may be considered to be in the YZ plane. In some embodiments, the surface may be arranged to bend in the XY plane so that the upper surface of the marker is arranged to be flat in height but curved from side to side.

[0039] In some embodiments, the pattern can be arranged to match the ambient light appearance of the photoluminescent marker with the appearance of the carpet on which the photoluminescent marker is mounted. In other embodiments, the photoluminescent marker can be arranged to match the ambient light appearance of a surrounding surface, such as a cabin wall surface or a portion of a chair or storage compartment. It will be appreciated that edge-to-edge printing of a pattern or color is desirable in terms of matching or contrasting with the appearance of the carpet or other surrounding surface, and providing an aesthetically pleasing appearance.

[0040] Printing may be performed by means of a printer suitable for printing markings with ink or coatings which are suitable for curing with UV radiation. The printer may be suitable for printing the ink or coating using inkjet technology. The printer may be arranged to cure the coating or ink in situ after printing or applying the photoluminescent material.

[0041] It has been found that the use of inks or coatings adapted to be cured by UV radiation is particularly advantageous and enables the printing of colours or patterns directly onto the photoluminescent material. Furthermore, it has been found that the inks or coatings are more durable. It has been found that the durability of UV-cured inks or coatings is significantly greater than that of solvent-cured inks.

[0042] Previously it has been considered necessary to use solvent inks to print on photoluminescent materials or on films used with photoluminescent materials. Such solvent inks are considered to have low durability and to be rather fragile. It has long been known that solvent inks can be damaged, removed or smudged, for example by simple contact with a finger. Therefore, prior art markers including photoluminescent materials or films printed with solvent inks must provide a housing or protective coating over the printed layer.

[0043] In contrast, UV cured inks and coatings have been found to be very durable and have increased wear resistance. The increased durability and wear resistance enables the design of products that do not require protective layers, thereby reducing the number of parts and reducing the weight and complexity of the product. Those skilled in the art will appreciate that weight reduction is very important in aircraft markings in aircraft. The markers may be used for aircraft sign markings or aircraft escape route markings.

[0044] It has also been found that a protective layer can be printed onto the marker, rather than having to provide an additional protective component. In some embodiments, the protective layer can be colored. In some embodiments, the protective layer can be textured. In some embodiments, the protective layer can be colored and textured.

[0045] In other embodiments, ink or paint is applied to the housing. It has been found that the pattern can be printed on the base of the housing or other parts of the marker. It has also been found that information such as part numbers and batch numbers can be printed on the base of the photoluminescent marker.

[0046] This information is important to the crash investigation team in an accident as being able to identify the part and batch number is critical. The ink or paint is extremely difficult to remove from the housing so the information is provided securely and permanently as part of the marking.

[0047] In a preferred embodiment, the printer may include a light emitting diode (LED) radiation source. The printer may include an LED arranged to emit radiation in the UV region of electromagnetic radiation. UV curing is a photochemical process in which UV light cures or dries ink or coating. The UV radiation may be a high intensity emission from an LED.

[0048] It has been found that UV curing allows for improved productivity and quality as well as performance. UV curing utilizes a photochemical reaction. Liquid monomers and oligomers are mixed with a photoinitiator and then exposed to UV radiation. The marking may be arranged to harden when exposed to UV radiation.

[0049] In some embodiments, the photoluminescent material comprises a flexible substrate. In some embodiments, the substrate may be supplied to the printer in a roll. It is desirable that the color or pattern may be applied to the photoluminescent material in long sections so that there are no interruptions or so that the interruptions in the pattern are greatly reduced. It has been found that the production speed of the finished product is greatly improved. In some embodiments, the photoluminescent substrate may be supplied to the printer in a roll. In some embodiments, the printed and cured photoluminescent marker may be rolled up when the photoluminescent marker leaves the printer. It may be desirable to store the photoluminescent marker in a rolled up state before installation in an aircraft. The roll of the photoluminescent marker may be arranged to have a radius from 0.1 m to 1.0 m. Preferably, the coating flexes with the photoluminescent marker and does not crack or split.

[0050] The method for making a photoluminescent marker according to the first aspect of the invention has the particular advantage that the method is suitable for printing directly onto a photoluminescent material on a flexible substrate (e.g. a substrate suitable for rolling up for storage). Conventionally, it has only been possible to apply the marking to the photoluminescent material by means of screen printing or by means of solvent-based digital printing. As discussed, screen printing limits the size of the printing area. In addition, it has been found that screen printing is not efficient for custom designs and is very time-consuming to set up and perform. It has been found that there are disadvantages to using solvent-based digital printing. The printed area requires a period of time to dry, during which leaching into the photoluminescent material may occur. In addition, it has been found that the ink used in solvent ink printing is not durable and is easily wiped off the photoluminescent material during use. It has been found that solvent-based pigments are prone to cracking if exposed to any flexing or expansion or contraction under pressure or temperature changes. Screen printing is very time-consuming to set up the process. Screen printing requires careful and time-consuming drying of the printed marking. Screen printed markings are also prone to fading during use.

[0051] In some embodiments, the substrate may include a vinyl substrate. The vinyl substrate may be flexible or may be at least partially rigid. In some embodiments, the vinyl substrate may be laminated to increase rigidity.

[0052] In other embodiments, the substrate may include a rigid substrate. In some embodiments, the substrate of photoluminescent material may include a curved surface or curved edges. The curvature may be in any of the planes described above.

[0053] According to a second aspect of the present invention, there is provided a photoluminescent marker manufactured according to the first aspect of the present invention.

[0054] According to another aspect of the present invention, there is provided an aircraft photoluminescent marker comprising a substrate and a layer comprising an ink or coating printed directly onto the substrate, wherein the substrate is one of a photoluminescent material and a housing, and wherein the ink or coating is a composition cured by UV radiation.

[0055] In some embodiments, the photoluminescent marker is printed with an ink or coating, wherein the ink or coating comprises an acrylic resin. Preferably, the coating or ink is suitable for curing with UV radiation and cures or dries very quickly. Curing can be within a few seconds. It should be understood that this is much faster than alternative methods in which the coating or ink is dried with heat or in air for several hours. Desirably, the ink or coating is arranged to cure within a few minutes. Typically, curing can be from less than 1 second to 1 minute, or more preferably from 0.1 second to 1 minute or from 0.5 second to 1 minute.

[0056] A particular advantage of curing a coating or ink with UV radiation is that the coating or ink cures quickly. This is advantageous in terms of managing workflow. Another advantage is that drying occurs before any leaching of the ink onto the photoluminescent material. Thus, the color or pattern can be more closely controlled. It has been found that an advantage of the rapid curing of the coating is that the ink does not leach into the photoluminescent material. It has been found that high resolution images can be formed in the coating.

[0057] It has also been found that the range of available colors is greatly increased. Using inkjet printing technology provides a range of colors and shades because inkjet technology provides a wide range of colors produced by mixing multiple base ink colors. In contrast, in the prior art, the ink is applied to the film as a solvent and the range of available colors is limited due to the use of the film.

[0058] In some embodiments, the coating or ink may include an optically clear acrylic resin. Preferably, the resin is optically transparent in the range of from 250nm to 1000nm or more preferably from 300nm to 600nm or from 400nm to 600nm. It is desirable that the resin is transparent or substantially transparent to electromagnetic radiation in this wavelength range so as to allow charging of the photoluminescent material and transmission of light emitted from the photoluminescent material. The photoluminescent material may be charged by electromagnetic radiation in the range of from 300nm to 550nm or from 300nm to 500nm. The light emitted from the photoluminescent material may be from 400nm to 600nm or more preferably from 450nm to 550nm.

[0059] Desirably, the coating or ink is flexible. In a preferred embodiment, the coating or ink is stretchable and can be arranged to flex, stretch or curl without breaking. An advantage of using coatings and inks that are suitable for stretching is that the coating or ink can be used on a substrate that is rolled up during storage or before application to an aircraft surface, or can be used on a substrate that is used in situations where the surface on which the marker is mounted during use is not flat. Photoluminescent markers are advantageously suitable for use on curved surfaces. The markers can be used on convex curved surfaces or concave curved surfaces or a combination of both.

[0060] In a particularly preferred embodiment, the coating or ink may be applied to the photoluminescent material on the flexible substrate. In a particularly desirable embodiment, the coating or ink may be applied to the photoluminescent material on the flexible substrate, and the photoluminescent marker may be arranged to be rolled up prior to installation. It will be appreciated that a coating or ink that does not crack is particularly advantageous.

[0061] Desirably, the photoluminescent material is arranged to be flexible.

[0062] In one embodiment, the coating or ink is applied directly to the surface of the photoluminescent material. The photoluminescent material may include photoluminescent particles dispersed in a resin. The resin may be an epoxy resin. Preferably, the epoxy resin is flexible. The resin may be coated onto a flame retardant substrate.

[0063] Other resins may be used, such as thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and the like.

[0064] In some embodiments, ink or paint can be applied to a flexible photoluminescent material supported on a flexible substrate. The photoluminescent marker can include a substrate and a photoluminescent material on the substrate and a paint or ink on the photoluminescent material. In some embodiments, the photoluminescent marker can be stored in a roll before installation. In other embodiments, the photoluminescent marker can be applied to a curved surface during use. It should be understood that the rolled-up photoluminescent marker can be easily installed in the aisle of an aircraft by unrolling the photoluminescent marker and cutting the marker into a certain length. In some embodiments, the photoluminescent marker can be set in a housing, and the housing can be flexible. In other embodiments, the photoluminescent marker is flexible and the housing is semi-rigid or rigid. It has been found that the use of a single-piece insert for the photoluminescent marker significantly reduces the installation time, especially the preparation time before installation. In some cases, it has been found that the reduction in preparation time can be as much as 80% of the allocated time for preparing to install the photoluminescent marker system. In this way, the installation time in the aircraft may be only 20% of the previously allocated time.

[0065] It will be appreciated that in some applications, markers may be applied to curved surfaces in an aircraft, particularly for photoluminescent markers used to identify exit doors or other components of an aircraft.

[0066] Applying the photoluminescent marker to a curved surface, particularly to a convex curved surface, will impose a degree of stretch on the substrate and the coating or ink. Preferably, the coating or ink is sufficiently stretchable so that the coating does not break during use. In a preferred embodiment, the coating or ink is stretchable so that the photoluminescent material on the substrate can be rolled up before installation without breaking the coating or ink. It will also be appreciated that a degree of stretching is advantageous because the coating or ink may be used on a photoluminescent marker that may be stretched or compressed under pressure or temperature changes when used in an aircraft. This may be particularly pronounced in the case of a long length of photoluminescent marker used to mark an emergency path along an aisle.

[0067] An advantage of the present invention is that the coating or ink can be more durable than traditional coatings.

[0068] Surprisingly, the light transmissive properties of UV curable inks and coatings have been found to be particularly suitable for use in conjunction with photoluminescent materials, allowing the photoluminescent emission to be transmitted and allowing electromagnetic radiation to pass through to effectively charge the photoluminescent pigment.

[0069] Another problem encountered with solvent-based digital printing of indicia is that the indicia are not durable. It has been found that on certain substrates, indicia applied with solvent-based pigments lack durability and, during normal use, may be erased or removed or damaged due to abrasive forces if in direct contact with the solvent-based digitally printed indicia. Therefore, it is undesirable to use photoluminescent indicia in situations where passengers or crew may come into contact with the photoluminescent indicia during normal use of the photoluminescent indicia in an aircraft.

[0070] Advantageously, the coating or ink used according to the first aspect of the invention is resistant to abrasion. It is desirable that the coating or ink is suitable for use in an environment where the marking object may be handled or touched during normal use.

[0071] The coating or ink may have a glossy finish or a matte finish. In some embodiments, the coating or ink may have an anti-glare finish. In some embodiments, the coating or ink may have a patterned finish.

[0072] According to a third aspect of the present invention, there is provided an emergency lighting system comprising one or more photoluminescent markers according to the second aspect of the present invention.

[0073] In a preferred embodiment, the photoluminescent marker further comprises a housing. Preferably, the photoluminescent material is disposed on a substrate. The photoluminescent material and the substrate may form an insert adapted to be inserted into the housing.

[0074] According to a fourth aspect of the present invention, there is provided an aircraft comprising an emergency lighting system according to the third aspect of the present invention.

[0075] According to a fifth aspect of the present invention, there is provided a method of installing an emergency lighting system according to the third aspect of the present invention, the method comprising installing at least one photoluminescent marker according to the second aspect of the present invention in an aircraft.

[0076] According to a sixth aspect of the present invention, there is provided an emergency lighting system suitable for being installed in an aircraft during use, the emergency lighting system comprising at least one photoluminescent marker, each photoluminescent marker comprising a shell and an insert, the shell being suitable for covering the insert, the insert comprising a photoluminescent material, the photoluminescent material being arranged to be charged through a portion of the shell covering the insert, the shell also comprising a coating, wherein the coating comprises a UV-curable coating.

[0077] The housing may comprise polycarbonate or thermoplastic polyurethane (TPU), acrylic or glass or other suitable material.

[0078] In some embodiments, the coating includes a protective finish. In some embodiments, the coating may include a patterned finish. The coating may have a glossy finish or may have a matte or semi-matte finish. In other embodiments, the coating may include an anti-glare finish. In some embodiments, the coating may be colored or at least partially colored.

[0079] The protective finish may be arranged to provide chemical resistance or abrasion resistance. Abrasion resistance may provide additional protection when used as a floor marker where the marker is exposed to foot traffic and the passage of food and beverage trolleys.

[0080] It has been found that the use of a UV curable coating allows a different finish to be provided compared to the prior art method where any protective coating must be sprayed onto the housing. The UV coating may include a pattern or logo.

[0081] Further aspects of the invention are set out in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] The present invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:

[0083] Figure 1 is a schematic diagram of an aircraft including a photoluminescent marker system according to an aspect of the present invention;

[0084] Figure 2 is a perspective view of a photoluminescent marker according to one aspect of the present invention;

[0085] Figure 3 is a perspective view of a housing with a coating according to another aspect of the present invention. DETAILED DESCRIPTION

[0086] Figure 1 is a schematic diagram of an aircraft including an emergency evacuation lighting system. A typical arrangement of the interior of a cabin 1 of a passenger aircraft is shown. The seats 2 are arranged in rows 3 on opposite sides of a central aisle 4. In this embodiment, five seats are shown in each row 3, the five seats being arranged in groups of two on one side of the central aisle 4 and in groups of three on opposite sides of the central aisle 4. However, this is not required and it will be appreciated that the number and arrangement of the seats 2 in each row 3 may be varied while providing a central aisle 4 which separates the groups of seats 2 in each row 3 for access in the direction of the length of the cabin 1. It will also be appreciated that a single central aisle may be provided or that dual aisles may be provided.

[0087] Exits 5 are provided at the front and rear of the cabin 1 to allow passengers to get on and off the aircraft in normal use and in emergency situations. Additional exits 5 are provided along the middle of the central aisle 4, usually opening above the wing (not shown) for use in emergency situations.

[0088] In an emergency, such as after a crash landing or aborted takeoff, the ceiling lighting system may be inoperable due to impact damage to the structure of the aircraft. In order to assist in the evacuation of the aircraft in the event that the normal overhead electrical lighting system fails or is blocked by smoke, a floor mounted emergency lighting system 6 is provided. The emergency lighting system 6 emits photoluminescent visible light to identify an escape route extending at floor level along the central aisle 4 between the seats 2 to the exit 5. The emergency lighting system typically includes two similar tracks 7, 8, which are arranged on opposite sides of the central aisle 4 and adjacent to the rows of seats.

[0089] Emergency roadway markers are provided on both sides of the aisle. Additional photoluminescent markers are provided to identify exits. In addition, photoluminescent markers may be provided to identify seat numbers or the location of power outlets or other components of aircraft equipment.

[0090] The photoluminescent marker according to the present invention is Figure 2 , the photoluminescent marker 10 includes a photoluminescent material 12 disposed on a substrate 14 and further includes one or more indicia 16 on the photoluminescent material, the indicia comprising an ink or coating adapted to be cured with ultraviolet (UV) radiation.

[0091] In this embodiment, the substrate comprises a flexible substrate. It should be understood that the substrate may be a rigid substrate. The flexible substrate is described in more detail in our co-pending application GB2577177, the entire contents of which are incorporated herein by reference. The photoluminescent material is applied to the flexible substrate. In some embodiments, the substrate may comprise a vinyl-based material substrate. In one embodiment, the photoluminescent marker is arranged to be rolled up before being installed in the aircraft cabin. The substrate having the photoluminescent material thereon is arranged to be supplied to the printer in a roll. The printer is arranged to print a coating or ink or a combination of coating and ink onto the photoluminescent material disposed on the flexible substrate. The flexible substrate is a flame retardant substrate. The substrate may be vinyl or thermoplastic polybutylene, PET TPU, PEGT, polycarbonate. The substrate may have a protective coating applied to the outer surface. In some embodiments, the printed and cured photoluminescent marker is rolled up when the photoluminescent marker leaves the printer. It may be desirable to store the photoluminescent marker in a rolled-up state before installation.

[0092] The photoluminescent material includes photoluminescent particles dispersed in a resin. In a preferred embodiment, the resin is an epoxy resin. The epoxy resin is flexible. It should be understood that other resins may be used, such as thermoplastic polyurethane (TPU), thermoplastic elastomer (TPE), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), etc.

[0093] The printer is arranged to apply a coating or ink to the photoluminescent material. The photoluminescent material may be introduced into the printer already on a substrate. The printer comprises a UV printer arranged to apply the coating or ink to the photoluminescent material. The printer may be a conventional printer suitable for printing with an ink or coating suitable for curing by UV radiation. Therefore, the printer will not be described in more detail here. In a preferred embodiment, the printer is suitable for printing the ink or coating using inkjet technology. The UV radiation is emitted by a light emitting diode (LED).

[0094] The coating or ink is arranged to be applied directly to the surface of the photoluminescent material. In other embodiments, the coating or ink is applied to the outer surface of the housing. Typically, the outer surface of the housing may have a protective coating.

[0095] The indicia may comprise patterns, text, images, block colours or logos and these are arranged to be printed directly onto the photoluminescent material.The photoluminescent material takes the form of photoluminescent pigments / particles dispersed in an epoxy resin.

[0096] A particular advantage is that a pattern or logo or other marking can be printed directly onto the photoluminescent material and no additional parts (such as a film or other element comprising the pattern) need to be provided and fixed in position relative to the photoluminescent material and the protective housing.

[0097] It will be appreciated that printing a pattern directly onto the photoluminescent material fed into the printer in roll form allows for printing with greater speed and efficiency. As a result, it has been found that manufacturing and assembly times have been significantly reduced. The printer may be arranged to produce a length of printed photoluminescent material. In this way, a photoluminescent marker is obtained on which the pattern extends over a greater length than was previously possible.

[0098] The pattern may be arranged to be printed directly on the photoluminescent material so as to match the ambient light appearance of the photoluminescent marker with the ambient light appearance of the carpet on or near which the photoluminescent marker is mounted when in use in an aircraft cabin. It will be appreciated that it may be desirable to provide the photoluminescent material with other appearances in ambient light so as to make the security features of the photoluminescent material less intrusive or disruptive in other locations, and that the photoluminescent material may be printed with a paint or ink arranged to blend in or complement other environments in an aircraft cabin.

[0099] In some applications of photoluminescent markers, the photoluminescent material is disposed on a support and formed as an insert 18. In this embodiment, the support comprises a base. The insert 18 is arranged to be inserted into a housing 20. The pattern is printed directly onto the photoluminescent material disposed on the base. The insert 18 is arranged to comprise a single piece insert, rather than a base and photoluminescent material and a film. It will be appreciated that a single piece insert 18 is easier to manufacture and install in an aircraft.

[0100] It has been found that the use of inks or coatings suitable for curing by UV radiation is particularly advantageous and enables the color or pattern to be printed directly onto the photoluminescent material. In addition, it has been found that the inks or coatings are more durable.

[0101] A particular advantage of this manufacturing method is that the ink or coating is printed onto the photoluminescent material, and the photoluminescent material can be disposed on a flexible substrate. The photoluminescent material disposed on the flexible substrate and adapted to be rolled up has specific characteristics in the form of a specific photoluminescent particle size distribution. Typically, the photoluminescent particles are dispersed in a flexible resin. D50 is the mass median diameter or (MMD). The D values ​​(D10, D50 and D90) are the intercepts of 10%, 50% and 90% of the cumulative mass. The size of D50 ranges from 10 μm-100 μm. In one embodiment, the D90 value can be as high as 200 μm. Methods for measuring D50 and D90 are conventional and include laser diffraction or electron microscopy.

[0102] Another advantage of the manufacturing method is that the ink or coating is not a solvent based ink or coating, so the solvent used in the process is significantly reduced, which also reduces the environmental impact of the manufacturing method of the photoluminescent marker.

[0103] In other embodiments, the substrate may comprise a rigid substrate. It has also been found that the substrate may comprise a curved surface. Depending on the application, the surface may be curved in the XY, XZ or YZ plane. The surface may be convex or may be concave. The marker may be curved in a horizontal plane.

[0104] In some embodiments, the ink or coating comprises an acrylic resin. Typically, the ink or coating is arranged to cure within a few minutes. Typically, the curing of the ink or coating is completed in less than one minute, and in one embodiment is completed in one second or less. The curing time of printing colors and patterns onto photoluminescent materials is greatly reduced, thereby increasing productivity and enabling customized printed patterns and products to be provided. It should be understood that this is much faster than alternative methods in which the coating or ink is dried with heat or dried in air for several hours. The rapid curing of the ink or coating is advantageous in terms of managing workflow. Another advantage is that curing occurs before the ink can leach from the coating or ink into the photoluminescent material. The ink used in printing and curing with UV has a greatly increased color range, and the use of inkjet printing technology provides a larger range of colors and tones than screen printing can provide.

[0105] In some embodiments, the coating or ink may include an optically clear acrylic resin. The resin is arranged to be optically transparent in the range from 400nm to 600nm. It is desirable that the resin is transparent or substantially transparent to electromagnetic radiation within these wavelengths so as to allow charging of the photoluminescent material and transmission of light emitted from the photoluminescent material. The photoluminescent material may be charged by electromagnetic radiation in the range from 300nm to 550nm or from 300nm to 500nm. The light emitted from the photoluminescent material may be from 400nm to 600nm or more preferably from 450nm to 550nm.

[0106] The coating or ink is flexible. In a preferred embodiment, the coating or ink is stretchable and can be arranged to flex, stretch or roll up without breaking. The use of coatings and inks suitable for stretching allows the coating or ink to be used on substrates (the substrate is arranged to be rolled up when stored or before installation), or can be used in situations where the surface on which the marker is mounted is uneven during use. It has been found that the marker can be used on curved surfaces. It has been found that the marker can be used on convex curved surfaces or concave curved surfaces.

[0107] Applying the marker to a curved surface, particularly a convex curved surface, will impose a certain degree of stretch on the substrate and the coating or ink. In one embodiment, the coating or ink is able to stretch sufficiently so that the coating does not break when in use. In a preferred embodiment, the coating or ink is able to stretch so that the photoluminescent material on the substrate can be rolled up before installation without the coating or ink breaking. It will also be appreciated that a certain degree of stretching is advantageous because the coating or ink can be used on the photoluminescent marker, which can be stretched or compressed when used in an aircraft as the aircraft expands and contracts in length (depending on the pressurization of the cabin). Therefore, it is necessary to allow the floor area of ​​the aircraft to expand and contract during use, and to allow for changes during flight. A particular advantage of the emergency lighting system manufactured according to the claimed invention is that the resulting marker system can expand and contract without breaking or damaging the coating. Therefore, a longer length of marker can be used compared to the 2m length of marker previously used. It will be appreciated that if the marker used has a longer length or is continuous or semi-continuous, fewer joints will be formed in the guide path.

[0108] In some embodiments, ink or coating is applied to a flexible substrate. The photoluminescent marker can be stored in the form of a roll before installation. The photoluminescent marker system can be arranged to include at least one photoluminescent marker according to the present invention. The photoluminescent marker can include a flexible photoluminescent marker, which can be applied to a curved surface and installed on the curved surface in use. In another embodiment, the photoluminescent marker according to the present invention can include a rolled-up photoluminescent marker, which is easily installed in an aircraft by unfolding the photoluminescent marker and cutting it into a certain length. In some embodiments, the photoluminescent marker is arranged in a shell. In a preferred embodiment, the shell 20 is also flexible. In other embodiments, the shell 20 is rigid or semi-rigid. It should be understood that in other embodiments, the photoluminescent marker is flexible and the shell 20 is relatively more rigid. In some embodiments, the shell 20 can be semi-rigid or rigid. It has been found that the use of a single-piece insert of a photoluminescent marker for an emergency lighting system in the aisle of an aircraft cabin significantly reduces the installation time. The preparation time can be reduced by 80% of the time required to prepare for the installation of the photoluminescent marker system.

[0109] Photoluminescent markers may be applied to curved surfaces in an aircraft, particularly for markers used to identify exit doors or other components of the aircraft.

[0110] The coating or ink has been found to be more durable than conventional coatings or inks used in screen printing applications and solvent-based digital printing. It is noted that screen printing setup is very time consuming and requires careful drying of the printed mark. It should also be noted that screen printed marks are susceptible to cracking and fading with use. Additionally, digitally printed solvent marks are not durable on certain substrates and may be erased or removed or damaged during normal use.

[0111] Advantageously, the coating or ink used in the method of the present invention is resistant to abrasion. The coating or ink is suitable for use in an environment where the marking object may be handled or touched during normal use. The coating or ink may have a glossy finish or a matte finish. In some embodiments, the coating or ink may have an anti-glare finish.

[0112] The invention also includes a method of installing at least one photoluminescent marker in an aircraft to provide an emergency lighting system, the method comprising providing a photoluminescent marker according to the invention and installing at least one emergency path route marker along both sides of an aisle of the aircraft. It is particularly advantageous to use a roll of flexible photoluminescent marker which can be easily unrolled, cut to length and installed in place along the aisle. Preferably it has a flexible housing.

[0113] An emergency lighting system is also provided, which includes at least one photoluminescent marker, each photoluminescent marker includes a shell 20 and an insert 18, the shell 20 is suitable for covering the insert 18, the insert 18 includes a photoluminescent material, the photoluminescent material is arranged to be charged through an upper portion 22 of the shell 20 covering the insert, and the shell also includes an external coating, wherein the coating includes a UV-curable coating printed on the shell.

[0114] The housing 20 may include polycarbonate. In other embodiments, the housing may be formed of thermoplastic polyurethane (TPU), acrylic or glass or other suitable materials. The housing may have a protective coating that is difficult to print on.

[0115] A UV curable coating 24 is provided on the outer surface of the housing. In this embodiment, the coating is patterned. The coating may be selected to have a glossy finish or may have a matte or semi-matte finish. The coating may also be provided with an anti-glare finish. The coating may also be colored or at least partially colored. The exterior coating may be a flat coating or a patterned coating. The exterior coating may be provided with a logo or a repeating pattern or a trademark on the outer surface of the housing.

[0116] In some embodiments, a pattern may be applied to the base of the shell to aid cutting of the shell when installed in an aircraft. In addition, a part number and a batch number may be applied to the base of the shell.

[0117] In some embodiments, a coating of UV curable ink or paint may be applied to provide a protective finish on the housing and photoluminescent material. The paint may be colored. The use of a colored protective coating allows the color to be applied from one longitudinally extending edge of the marker to the opposite longitudinally extending edge. A uniform color may be obtained across the marker. This contrasts with the appearance of prior art products in which the housing is typically not colored so there is a colored appearance of photoluminescent strips defined by sharp edges. Providing edge-to-edge color enhances the appearance of the marker and can help camouflage the marker until it is needed in an emergency.

[0118] The protective finish may be arranged to provide chemical resistance or abrasion resistance. Abrasion resistance may provide additional protection when used as a floor marker where the marker is exposed to foot traffic and the passage of food and beverage trolleys.

[0119] It has been found that the use of a UV curable coating allows a different finish to be provided compared to the prior art method where any protective coating must be sprayed onto the housing.

[0120] The skilled person will understand that the photoluminescent marker must meet the requirements of DO-160 for environmental requirements, CS25.812 for photoluminescent signs, and AC25.812 for photoluminescent floor path markings. For recycling and waste requirements such as ISO14001 related to environmental management, appropriate standards should also be met.

Claims

1. A method of manufacturing an aircraft photoluminescent emergency path marker for use in an aircraft cabin, the aircraft photoluminescent emergency path marker comprising a photoluminescent material and a housing arranged to protect the photoluminescent material, the method comprising: Providing inks or coatings that are suitable for curing with ultraviolet radiation, i.e., UV radiation, and that are flexible and stretchable once cured; printing one or more indicia directly onto the photoluminescent material of the photoluminescent emergency path marker using the ink or paint; as well as curing the marking made from the ink or coating using UV radiation; The marking comprises at least one of a pattern, text, an image or a logo, and the photoluminescent material comprises photoluminescent particles having a size distribution of D50 in the range of 10 μm-100 μm, the photoluminescent particles are dispersed in a flexible resin, and the photoluminescent material is applied to a flexible substrate so that the printed photoluminescent material-substrate combination is suitable for rolling up.

2. The method according to claim 1, wherein: The UV radiation is emitted by LEDs, or light emitting diodes.

3. The method according to claim 1, wherein: The housing is also flexible.

4. The method according to claim 1, wherein: At least one of the photoluminescent material and the housing is arranged to be flexible such that the at least one can be bent to a radius of from 0.1 m to 1.0 m.

5. The method according to claim 1, wherein: The substrate is supplied to the printer in a roll form.

6. The method according to claim 1, wherein: The substrate includes a curved surface.

7. The method according to claim 1, wherein: The coating or ink includes an optically clear acrylic resin.

8. An aircraft photoluminescent emergency path marker manufactured by the method according to claim 1.

9. An aircraft emergency lighting system comprising an emergency exit path, the emergency exit path comprising one or more photoluminescent emergency path markers manufactured by the method of claim 1.

10. An aircraft photoluminescent emergency path marker for use in an aircraft cabin, the aircraft photoluminescent emergency path marker comprising a photoluminescent material, a housing arranged to protect the photoluminescent material and a layer containing an ink or paint marking printed directly onto the photoluminescent material, the photoluminescent material comprising photoluminescent particles having a size distribution of D50 in the range from 10 μm to 100 μm, the photoluminescent particles being dispersed in a flexible resin, the ink or paint forming the marking being a composition that is cured by UV radiation and is flexible and stretchable once cured, and the photoluminescent material being applied to a flexible substrate so that the printed photoluminescent material-substrate combination is suitable for rolling up, and the marking comprising at least one of a pattern, text, an image or a logo.

11. The aircraft photoluminescent emergency path marker according to claim 10, wherein: The substrate is curved.

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