FR2992049A1 - Luminaire for safety pictogram representing graphic symbol e.g. arrow, for indication of safety information in corridor, has light source generating incident excitation radiation towards pictogram formed by phosphor material layer - Google Patents

Abstract

The luminaire has a housing mounted with a light source (20), and a pictogram (10) arranged opposite the light source, where the pictogram is arranged on a side of a light exit face of the light source. The light source includes organic LEDs that generate an incident excitation radiation directed towards the pictogram. The pictogram is formed by a phosphor material layer (13) deposited in the form of graphic symbols (11, 12), where the phosphor material layer is capable of re-emitting radiation in the visible range when it is subject to the incident excitation radiation.

Description

The invention relates generally to safety lighting and relates more particularly to a pictogram safety luminaire representing at least one graphic symbol intended for the signaling of safety information in a place. receiving the public, of the type comprising a housing in which is mounted at least one light source and at least one pictogram arranged opposite said light source on the side of a light outlet face of said luminaire.

Such a luminaire is well known to those skilled in the art, in particular by the example shown in FIG. 1 of the patent document EP 1 569 191. It aims to display a luminous signage in the form of safety pictograms and to provide automatically a supplementary light source for emergency lighting or marking for the evacuation of persons, in case of failure of the normal lighting system and in case of fire in public buildings (ERP). The construction of such luminaires must meet the requirements of the French standard NF EN 60598-2-22 currently in force. They are very widely installed, for example above emergency exits, in stairwells, along corridors, etc.

These luminaires may have a translucent cover for the support of the pictogram. The pictogram represents one or more graphic security symbols (character running, arrow, etc.) in predetermined security colors, typically green and white, and is for example printed on a semi-rigid film maintained in position behind lid. The pictogram may also be in the form of a sticker for coating the front wall of the lid. Backlighting or illumination by the edge of the pictogram with one or more light-emitting diodes is commonly employed. With such an arrangement, however, it is difficult to obtain a perfectly homogeneous distribution of the luminous flux over the entire pictogram and to ensure compliance with the regulatory luminance values in the various security colors of the pictogram according to the standards. However, inconsistencies in luminance are likely to affect the contrast between the various security colors of the pictogram and therefore, its visibility. Also, it is essential that backlit light or backlit light-emitting diodes be used in combination with additional complex optical devices, such as diffusion lenses, to overcome at least some of these disadvantages.

There is therefore a need for an improved pictogram safety luminaire with improved visibility, which is simple to implement while ensuring a perfect uniformity of the required luminance in each safety color of the pictogram. To this end, the security luminaire of the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that said light source is a source generating an incident radiation of excitation directed towards said pictogram, said pictogram consisting of at least one layer, deposited in the form of said pictogram, of at least one phosphor material able to re-emit radiation in the visible range when it is subjected to said incident radiation; 'excitation. Thanks to this arrangement, the light source is not used as a source of illumination of the pictogram, in accordance with the luminaires of the prior art, but as a source of excitation of a layer of phosphor materials whose retransmission of the excitation incident radiation in the visible range makes it possible to display the pictogram. Selective deposition in the form of a layer of suitable phosphor materials advantageously enables the luminance intensity required in each safety color of the pictogram to be controlled with great precision so that it is observable with sufficient contrast. According to other advantageous characteristics of the safety luminaire according to the invention, taken alone or in combination: said excitation radiation-generating light source is able to emit incident excitation radiation in the ultraviolet or blue; said excitation ray-generating light source comprises a plurality of light-emitting diodes arranged in a matrix on a support plate arranged behind and substantially at a distance from said layer, so as to excite said layer in a uniform manner; said excitation radiation generating light source comprises a plurality of surface light sources based on organic light-emitting diodes deposited on a substrate, so as to form a flat luminous surface adapted to excite said layer in a uniform manner; said layer is deposited directly at an upper face of said substrate, so as to be superimposed on said planar luminous excitation surface; it comprises a transparent or translucent plate, at least one surface of which is carrying said layer, said light source generating excitation radiation being positioned in at least one slice of said transparent or translucent plate, so as to ensure excitation of said layer; said layer is deposited on a sheet having a predetermined appearance in the absence of incident excitation radiation, chosen from among the following aspects: translucent, transparent, reflective, opaque; said layer comprises different phosphor materials distributed within said layer and separated in different regions of said layer so as to form said at least one graphic symbol; said layer comprises at least a first green emitting phosphor material and a second emitting phosphor material in response to said incident excitation radiation. Other characteristics and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the accompanying drawings, in which: - Figure 1 schematically illustrates an exploded view of a safety luminaire according to the invention. FIG. 1 schematizes a pictogram 10 and a light source 20, which cooperate in a security luminaire according to the invention: It is possible to list several possible graphic security symbols for the representations of the pictograms displayed by the security luminaries, especially for emergency evacuation signaling functions. According to the example of FIG. 1, the pictogram 10 comprises a first security graphic symbol 11 associated with a second security graphic symbol 12, whose shapes and chromatic coordinates of their respective security colors are specified by the ISO 3864 standard. 1. The first symbol 11 typically represents a green character crossing a white door on a green background and the second symbol 12 represents a directional arrow in white on a green background. According to the invention, the pictogram 10 may be composed from a layer 13 based on phosphor materials adapted to respond to an excitation light source 20, intended to generate towards the pictogram 10, an incident radiation of excitation of appropriate wavelength, preferably but not exclusively in the field of ultraviolet (UV). In general, any known source of UV excitation can be used according to the invention. However, preference will be given to the use of light-emitting diodes (LEDs), particularly because of their low cost and their ease of installation and use. Thus, in a first embodiment, the excitation light source 20 comprises a plurality of UV LEDs arranged in a matrix on a support plate 21, made for example in the form of an electronic card, preferably arranged behind and substantially away from the layer 13 based on phosphor materials representing the pictogram 10, in order to excite the layer 13 of phosphor materials in a uniform manner and in particular avoiding the effect of "hot spots" inherent in the use of the LEDs ( point sources). Alternatively, LEDs capable of emitting incident excitation radiation in the blue domain can also be used to excite the layer 13 of phosphor materials, because of their lower cost compared to UV LEDs, although such excitation involves a relatively less efficient conversion from the phosphor materials. In another embodiment, the excitation light source may comprise a plurality of organic light emitting diode (OLED) surface light sources deposited adjacent to each other. on a substrate 22, preferably arranged behind and substantially at a distance from the layer 13 of phosphor materials, so as to form a flat luminous surface to excite the layer 13 in a uniform manner.

More precisely, the layer 13 consists of several phosphor materials chosen to have a high absorption coefficient of the incident excitation radiation. They are also chosen to re-emit, under excitation, radiation in the visible range, preferably with high efficiency, according to the respective chromatic coordinates required by the security colors specified by the standard. In this case, the layer 13 comprises a first green emitting phosphor material and a second white emitting phosphor material, each of these materials preferably having the same absorption wavelength so as to be simultaneously excited by the same incident radiation of excitation. In addition, the layer 13 of phosphor materials is deposited in such a way that it draws the form specified by the standard of the respective security symbols 11 and 12 of the pictogram 10. Thus, the first and second phosphor materials are distributed within the layer 13 and separated in different regions of the layer 13 so as to form the graphic symbols 11 and 12. The deposition of the layer 13 of phosphor materials for the representation of the pictogram 10 can be performed on a semi-rigid sheet, material thermoplastic for example, according to any known deposition technique, for example but not limited by screen printing techniques or by techniques of the inkjet or offset type. For example, the deposition by one of these techniques can be carried out by dissolving or dispersing the phosphor materials in at least one solvent, for example of the aqueous or organic type, depending on the chemical nature of the phosphor materials and the technique employed. Alternatively, a layer of phosphor materials for the representation of the first graphical symbol 11 of the pictogram 10 may be deposited according to the preceding techniques on a first semi-rigid sheet forming a first security signaling label 131 of the luminaire and a layer of phosphor materials for the representation of the second graphic symbol 12 of the pictogram 10 may be deposited on a second semi-rigid sheet forming a second security signaling tag 132 of the luminaire, intended to be positioned in the luminaire adjacent to the first label.

Preferably, the layer 13 of phosphor materials is deposited on at least one sheet, which has a predetermined appearance in the absence of incident excitation radiation, which is selected from the following aspects: translucent, transparent, reflective, opaque. Thus, out of excitation, the layer 13 of phosphor materials arranged in the luminaire according to the invention may have different visual aspects, which advantageously make it possible to propose different aesthetic embodiments (transparent effect, mirror effect, etc.). In addition, the layer 13 of phosphor materials can be adapted so that in the absence of the phenomenon of luminescence, ie out of excitation, the pictogram is nevertheless visible under natural light, by playing on the shades of the phosphor materials used in the layer 13. The phosphor materials used for producing the layer 13 representing the pictogram 10 are phosphor materials conventionally used in luminescence applications and will of course be chosen as a function of the excitation light source used. Preferably, the phosphor materials that can be used are adapted to emit visible radiation in response to excitation in the ultraviolet range or alternatively to excitation in the blue region. Such materials may for example be chosen in the field of organic or inorganic phosphors. The persistence times are short (a few tens of ms at most). The phosphor charge of different chemical compositions is adjusted so that the pictogram, under a sufficiently uniform UV or blue excitation radiation, offers a contrast C (defined as the ratio of the luminances Lmax / Lmin within the same color or Lblanc / Lvert between the two colors) in accordance with the requirements of NF EN 60598-2-22. According to one embodiment, the excitation light source 20 for the pictogram 10, is arranged in a reflector box, not shown. This housing may comprise reflective edges protruding at the periphery of the support plate 21, respectively from the substrate 22, for effectively directing the excitation radiation towards the pictogram 10 positioned opposite the support plate 21, respectively of the In addition, the layer 13 of phosphor materials deposited on at least one safety signaling label can be positioned opposite the excitation light source 20, by resting on the top of the protruding reflecting edges, so as to be disposed substantially at a distance from the excitation light source 20. A translucent lid, not shown, can be provided to cover the whole, advantageously maintaining the label or labels in position against the top of the projecting reflective edges. Alternatively, the layer 13 of phosphor materials may be deposited directly on one face of the front wall of the cover designed to face the plate 21.

In the case where the excitation light source 20 is in the form of an OLED device, the effect of "hot spots" is non-existent. Also, in this case, the layer 13 of phosphor materials may advantageously be deposited in a thin layer directly at an upper face of the substrate 22 on which the OLED device is formed, thus being superimposed on the plane luminous surface of 'excitation. According to an alternative embodiment not shown, the security luminaire may comprise a transparent or translucent plate, at least one surface of which bears the phosphor material layer representing the pictogram, and the excitation light source is positioned according to at least one slice of the plate, so as to ensure excitation of the layer of phosphor materials including diffusion through the thickness of the plate. The excitation light source is for example in the form of one or more LEDs connected to a printed circuit. The combination according to the principles described above of the excitation light source 20 and the layer 13 of phosphor materials representing the pictogram 10, has the advantage of substantially improving the luminance homogeneity within a color and the contrast between two colors of the pictogram displayed by the luminaire.

Claims (9)

REVENDICATIONS1. Safety pictogram luminaire representing at least one graphic symbol for signaling security information in a public place, of the type comprising a housing in which is mounted at least one light source (20) and at least one pictogram (10) arranged opposite said light source (20) on the side of a light exit face of said luminaire, characterized in that said light source (20) is a source generating an incident excitation radiation directed towards said pictogram (10), said pictogram consisting of at least one layer (13), deposited in the form of said pictogram, of at least one phosphor material able to re-emit radiation in the visible range when it is submitted to said incident radiation of excitation. 2. Luminaire according to claim 1, characterized in that said light source (20) generating excitation radiation is capable of emitting incident radiation excitation in the field of ultraviolet or blue. 3. Luminaire according to any one of claims 1 or 2, characterized in that said light source (20) generating excitation radiation comprises a plurality of light-emitting diodes arranged in a matrix on a support plate (21) disposed rearwardly. and substantially remote from said layer (13) so as to excite said layer (13) uniformly. 4. Luminaire according to any one of claims 1 or 2, characterized in that said light source (20) generating excitation radiation comprises a plurality of surface sources of light based on organic light-emitting diodes, deposited on a substrate ( 22), so as to form a flat luminous surface adapted to excite said layer (13) uniformly. 5. Luminaire according to claim 4, characterized in that said layer (13) is deposited directly at an upper face of said substrate (22), so as to be superimposed on said planar luminous surface of excitation. 6. Luminaire according to any one of claims 1 or 2, characterized in that it comprises a transparent or translucent plate, at least one surface is carrying said layer (13), said light source (20) generating radiation excitation device being positioned along at least one slice of said transparent or translucent plate, so as to ensure an excitation of said layer (13). 7. Luminaire according to any one of the preceding claims, characterized in that said layer (13) is deposited on a sheet having a predetermined appearance in the absence of incident excitation radiation, selected from the following aspects: translucent, transparent , reflective, opaque. 8. Luminaire according to any one of the preceding claims, characterized in that said layer (13) comprises different phosphor materials distributed within said layer (13) and separated in different regions of said layer (13) so as to form said at least one graphic symbol. 9. Luminaire according to any one of the preceding claims, characterized in that said layer (13) comprises at least a first phosphor material emitting in the green and a second phosphor material emitting in the white, in response to said excitation incident radiation. .