AU2013224702B2

AU2013224702B2 - Light

Info

Publication number: AU2013224702B2
Application number: AU2013224702A
Authority: AU
Inventors: Gerhard Rotgeri; Kai Hendrik Sabla; Stefan Volpert
Original assignee: CEAG Notlichtsysteme GmbH
Current assignee: CEAG Notlichtsysteme GmbH
Priority date: 2012-09-13
Filing date: 2013-09-05
Publication date: 2015-07-09
Anticipated expiration: 2033-09-05
Also published as: EP2709088A2; EP2709088B1; AU2013224702A1; DE202012008800U1; EP2709088A3

Abstract

Abstract A light (1), in particular a safety light or emergency sign light, comprises a transparent light-guiding and distributing plate (2), a number of LEDs (4) assigned to at least one light entry edge (3) of the light-guiding and distributing plate (2), and at least one pictogram (6) assigned to a lateral light-emitting surface (5) of the light-guiding and distributing plate (2). In order to realize a light of a flat design and with a uniform illumination in particular of the pictogram along with a simple construction and in a cost-efficient manner an adhesive layer (7) structured for light distribution is arranged between the pictogram (6) and the light-emitting surface (5). Figure 1 6,112 8 /9,13 7,10 6,11

Description

1 Light Technical Field Especially in the field of emergency and safety lighting a number of lights are known which are arranged to mark an escape route or the like in a building. Such lights are in particular safety or emergency sign lights. Background In one type of such a light same comprises at least one transparent light-guiding and distributing plate as well as a number of LEDs (light-emitting diodes) assigned to at least one light entry edge of the plate. In addition, a pictogram is assigned to at least one lateral light-emitting surface of the light-guiding and distributing plate. The pictogram may be directly printed to the light-emitting surface or connected to same by a translucent and self-adhesive film. Such a light is of a flat design and can be mounted in different ways. It may be a disadvantage of such a light that the light distribution is unbalanced. As a rule, the illumination of the pictogram is better in a region closer to the LEDs. In a further development of such a light a reflection device may be assigned to the light guiding and distributing plate opposite to the light entry edge. Moreover, small structures or printed structures may be assigned to the light-emitting surface(s) of the respective plate, which achieve an enhanced and uniform illumination of the entire light-emitting surface and, thus, of the respective pictogram. A disadvantage of such a light may be the additional arrangement of such plates provided with structures, or the application of the respective structures, to obtain a light-emitting surface which is illuminated in a uniform manner. Also, such lights usually require a light frame retaining the various components in a correct orientation relative to each other. Thus, a need exists to improve a light of the above-described type such that a light of a flat design and with a uniform illumination in particular of the pictogram can be realized along with a simple construction and in a cost-efficient manner. Summary An aspect of the present disclosure provides an arrangement of an adhesive layer structured for light distribution between the pictogram and the light-emitting surface. This means that a corresponding structure is directly provided by the adhesive, respectively adhesive layer, which allows a uniform and good illumination of the pictogram, wherein the 2 light distribution in respect of the pictogram is controlled by the adhesive layer to be very uniform and bright. An aspect of the present disclosure provides a light, in particular a safety light or emergency sign light, comprising a transparent light-guiding and distributing plate, a number of LEDs assigned to at least one light entry edge of the light-guiding and distributing plate, and at least one pictogram assigned to a lateral light-emitting surface of the light-guiding and distributing plate, wherein an adhesive layer structured for light distribution is arranged between the pictogram and the light-emitting surface. The adhesive layer may be applied to the light-emitting surface and/or to the pictogram backside of the pictogram pointing to the light-emitting surface. It is also possible to apply the adhesive layer including structures only in places so as to ensure a sufficient and bright illumination in the area of important portions of the pictogram, while in other areas light is reflected back into the light-guiding and distributing plate, for example, by a total reflection at the respective boundary surfaces. In this manner the light distribution is controlled by the application of the structured adhesive layer. It is also possible that the application of the adhesive layer is realized both on the backside of the pictogram and the light-emitting surface such that adhesive layers applied to different surfaces do not overlap or are applied complementary relative to each other. The corresponding structuring of the adhesive layer can in particular be realized such that the adhesive layer including a predetermined light-distributing pattern is applied at least in parts and/or is formed with this light-distributing pattern. This means that it is likewise possible that an adhesive layer is applied to the entire surface of the light-emitting surface or the pictogram backside, with the light-distributing pattern being provided only at predetermined and selected places, however. It is possible to apply the adhesive layer directly to the corresponding surface or, if applicable, also use a structured adhesive film. The latter is stuck onto the respective surface correspondingly, whereby it is also possible that such a sticking on is carried out only in certain areas to obtain the desired illumination of the pictogram. In this connection it is also possible to apply a respective adhesive film to both the light-emitting surface and the backside of the pictogram, again, in a corresponding complementary manner or non overlapping.

3 Different methods may be used to directly apply a corresponding adhesive layer, wherein preferably an application is realized using stencil printing, screen printing, ink-jet printing, dispensers or punched patterns. To allow a simple mounting of the pictogram same may be formed as a translucent film with a corresponding safety sign or emergency sign. It is also conceivable to use a pictogram plate or other pictograms having a greater thickness. The above aspects apply analogously to an arrangement of a pictogram on both sides of the light-guiding and distributing plate. It is furthermore possible that the adhesive layer and/or the pictogram in the form of a film plate or the like contains, for example, a corresponding light-scattering pigment for the scattering of light. This ensures that the corresponding structures of the adhesive layer do not result in corresponding structures in the light distribution in the pictogram. Instead, corresponding structures are not resolved. Depending on the size and design of the corresponding structures different, or different amounts of a corresponding light-scattering pigment may be contained in the adhesive layer and/or pictogram film, respectively plate. In order to facilitate the construction of the light further, with only a few additional devices for mounting or building up the light, the LEDs may be arranged in the form of an in particular self-adhesive LED-illuminated strip or band along a corresponding light entry edge. This means that an LED-illuminated strip or band of a corresponding length is arranged directly along the light entry edge and fixed there. This fixing may also be realized directly by means of the strip or band if same have self-adhesive properties. In addition to a self-adhesive arrangement of a corresponding LED-illuminated strip same may also be fixed by other fixing measures, such as locking, screwing, riveting, welding, inserting into holders or similar measures. Also, it is conceivable that, for example, such LEDs are arranged on two opposite light entry edges, or also along all edges of the respective light, respectively light-guiding and distributing plate. As the light can be constructed from components that are directly connected to each other it is a particular advantage if the light is constructed without a frame. Thus, no additional devices are necessary for fixing the individual components of the light to each other. The 4 light has a very compact structure and can be mounted, for example, on a corresponding ceiling, wall or pendulum suspension, directly by insertion, or in another way. Of course, it is possible that the light according to the invention is additionally provided with a frame, for example, for decorative reasons. The construction of the light may further be facilitated if, in the appropriate case, the adhesive layer can be applied fully automatically. This means that, depending on the pictogram used, the adhesive, respectively adhesive layer is applied by a machine. If the adhesive layer is applied using screen printing different screens can be employed for the structuring. These are basically amplitude-modulated and frequency-modulated screens. In the amplitude-modulated screen the corresponding screen dots have a strict geometrical arrangement with respect to each other. This means that they have in particular always the same distances between them. As may be necessary the screen dots may have different sizes, however, with smaller screen dots for areas to be illuminated to a greater extent and with correspondingly larger screen dots for pictogram areas to be illuminated to a smaller extent. In a frequency-modulated screen respective screen dots are arranged relative to each other randomly, but always have the same size. This means that more screen dots are provided for brighter areas and correspondingly fewer screens dots for darker areas for coupling out light from the light-guiding and distributing plate. Of course, other variations of the structures of the adhesive layer are also feasible, such as structuring only in certain areas, structuring by different structure elements, if necessary, also of different sizes and the like. Brief Description of the Drawings An advantageous embodiment of the invention will be explained in more detail below by means of the figure depicted in the attached drawing. In the drawing: Fig. 1 shows an exploded, perspective view of an embodiment of a light according to the invention, and 5 Fig. 2 shows a schematic diagram of the functional principle. Detailed Description A corresponding light 1 according to the invention as shown in Fig. 1 comprises different parts that are assembled to form a light of a flat design and with a compact structure. In particular, the light 1 according to Fig.1 may be frameless. Corresponding devices for holding, respectively mounting the light are not illustrated. However, such a light can be used for ceiling, wall or pendulum mounting, and pictograms may be arranged on both sides of the respective light. The electrical supply and contacting possibilities for the light according to Fig. 1 may be arranged in the corresponding mounting devices. As a rule, only an electrical connection to the illuminants is necessary. The light 1 shown in Fig. 1 comprises a central light-guiding and distributing plate 2. This plate is made of a transparent or at least translucent material. One example for such a material is polycarbonate, polymethyl methacrylate (PMMA) or also another corresponding material. In the embodiment shown the light-guiding and distributing plate 2 has a rectangular cross-section with a uniform thickness. One edge of the plate, see the light entry edge 3 at the upper end in Fig. 1, is assigned an LED strip 12 having a number of LEDs 4 (light-emitting diodes). The assignment of the corresponding strip, or band, may also be realized along another edge or several edges. Preferably, a strip-shaped reflector 14 is arranged opposite the corresponding light entry edge 3. The light-guiding and distributing plate 2 includes two lateral light-emitting surfaces 5. In the embodiment shown each of these lateral light-emitting surfaces 5 is assigned a pictogram 6 in the form of a pictogram film 11. The corresponding pictogram 6 is applied to the entire surface of the light-emitting surface. It is also possible, however, that the pictogram 6 is surrounded by a pictogram-free marginal area on the corresponding light emitting surface. The pictogram 6 of Fig. 1 serves to mark an escape route and, as a rule, comprises two colors, e.g. white and green. Of course, more colors or other colors are usable.

6 An adhesive layer 7 is applied between the pictogram 6 and the light-emitting surface 5. The adhesive layer 7 may be applied to the light-emitting surface or to a pictogram backside 8 of the pictogram 6 pointing to the light-emitting surface. Also, it is possible that the corresponding adhesive layer is applied to both surfaces, without or only with a small overlap, and in particular complementarily. The adhesive layer has a structuring which, in Fig 1, is substantially formed by a plurality of adhesive dots arranged in a screen-like manner. The adhesive dots may be of uniform sizes and have a uniform distribution so that adhesive dots of the same size are arranged at same intervals. Also possible are differently sized adhesive dots and/or different arrangement structures, where applicable also with areas without adhesive dots. The density or geometrical shape of the corresponding adhesive dots may vary as well. Preferably, the adhesive is directly applied to one of the surfaces, e.g. by screen printing. It is also possible to use an adhesive film having a corresponding screen which is formed of adhesive dots or the like. The corresponding screen generates a light distribution pattern 9 through the adhesive, which pattern supports a light emission towards the pictogram at least in certain areas of the light-guiding and distributing plate to achieve a uniform and bright illumination in particular of these areas of the pictogram. Of course, the light distribution pattern may also be formed across the entire light-emitting surface 5 so as to allow, as a whole, a uniform and bright illumination of the pictogram 6. The corresponding light distribution pattern is determined to match with the pictogram, and then applied in a respectively predetermined manner to the light-emitting surface 5 of the light-guiding and distributing plate or the pictogram backside 8. Of course, the light distribution pattern may be formed on different light-emitting surfaces 5 of a light-guiding and distributing plate in various ways, for example, if different pictograms are arranged on the two light-emitting surfaces. Fig. 2 shows a section through the light according to the invention to schematically depict the light emission. Light from the respective illuminant, see Fig. 1, is incident on the lateral light-emitting surfaces 5, see the exemplarily shown light beam 16. In areas of the light-emitting surface 5 where no adhesive is provided a corresponding light is totally reflected, viz. is reflected 7 back into the light-guiding and distributing plate 2. In areas of the light-emitting surface 5 provided with an adhesive a corresponding total reflection angle is so small or even negative due to the quite similar or even higher optical density with respect to the light guiding and distributing plate that a corresponding light beam 16 is not reflected, but coupled into the adhesive layer and transmitted to the pictogram film or pictogram plate. The pictogram film or plate, again, has a very similar or higher optical density as compared to the adhesive, so that the light beam is correspondingly coupled into the film or the plate with the pictogram. In a possible system, for example, the light-guiding and distributing plate 2 made of polymethyl methacrylate has a refractive index of 1.49, the adhesive 7 has a refractive index of 1.48, and the pictogram film (polyvinyl chloride) has a refractive index of 1.54. This means that the difference of the refractive indexes between the adhesive and the plate is very small and prevents light beams having an angle of incidence of < 6.70 relative to the respective inner surface of the plate from being coupled into the adhesive. However, any light beams having greater angles of incidence will be coupled into the adhesive and ultimately transmitted to the pigment film or plate. In order to prevent that corresponding structures of the adhesive layer result in light distribution structures and, at the same time, ensure that the pictogram is sufficiently visible also from a greater viewing angle, the light in the adhesive layer or pictogram film or plate is scattered. Such a scattering can be achieved, for example, by a corresponding light-scattering pigment being contained in the adhesive and/or in the pictogram film or plate. Such a pigment is designated with reference number 15 in Fig. 2.

Claims

1. A light comprising: a transparent light-guiding and distributing plate, a number of LEDs assigned to at least one light entry edge of the light-guiding and distributing plate, at least one pictogram assigned to a lateral light-emitting surface of the light-guiding and distributing plate, and an adhesive layer structured for light distribution arranged between the pictogram and the light-emitting surface, wherein the adhesive layer includes a predetermined light distribution pattern.

2. The light according to claim 1, wherein the adhesive layer is applied to the light emitting surface and/or to the pictogram backside of the pictogram pointing to the light-emitting surface.

3. The light according to claim 1 or 2, wherein the adhesive layer includes the predetermined light distribution pattern in predetermined places and/or the adhesive layer is formed with the predetermined light distribution pattern.

4. The light according to any one of the preceding claims, wherein the adhesive layer is a structured adhesive film.

5. The light according to any one of the preceding claims, wherein the adhesive layer is applied using stencil printing, screen printing, ink-jet printing, dispensers or punched patterns.

6. The light according to any one of the preceding claims, wherein the pictogram is formed as a translucent film or plate with safety signs or emergency signs.

7. The light according to any one of the preceding claims, wherein the LEDs are arranged in the form of an in particular self-adhesive LED-illuminated strip or band along the light entry edge.

8. The light according to any one of the preceding claims, wherein the light is constructed without a frame. 10152269 9

9. The light according to any one of the preceding claims, wherein the adhesive layer can be applied fully automatically.

10. The light according to any one of the preceding claims, wherein the adhesive layer comprises at least in part amplitude-modulated and/or frequency-modulated screens.

11. The light according to any one of the preceding claims, wherein the adhesive layer and/or pictogram film/plate contain a light-scattering pigment.

12. The light according to any one of the preceding claims, wherein the light is a safety light or an emergency sign light. CEAG Notlichtsysteme GmbH Patent Attorneys for the Applicant SPRUSON & FERGUSON 10152269