FR2786573A1 - Indicator light using light emitting diode includes coupling with plane input surface on optical fibre bundle used to convey light to remote location - Google Patents

Abstract

the diode and optical fibre bundle use plane surfaces for efficient transfer of light energy. The signaling system uses a light emitting diode which has its output surface made practically plane. This is intended to match the input surface (30) of the light guide (14) which is also machined to provide a plane surface. A ferrule is provided to keep the diode and light guide in alignment, and these components are supported in a stirrup with a guide slot (41-48). The stirrup may be articulated on a support block (42). The light guide is able to carry the light from the light emitting diode to a remote position away from the light source.

Description

SIGNALING SYSTEM FOR OBSCURE PREMISES USING
LIGHT CONDUCTORS AND COUPLING METHOD
OF A LIGHT-CONDUCTING DIODE AND CONDUCTOR
The present invention relates to a signaling system for premises with very low illumination using a light conductor and a light-emitting diode and to a method of coupling a light conductor with a light-emitting diode.

 Current techniques for marking up materials used in very low illuminance, allowing only a practically scotopic or low mesopic vision, consist essentially of electroluminescent panels supplied by an electrical conductor. Such devices cannot be easily used in rooms with very low lighting because the electrical wire for supplying the electroluminescent panels must be connected to an electrical outlet and it is inconvenient to leave it lying on the ground.

 French Patent 2,706,018 describes the use of a light conductor with lateral light loss to produce beaconing on the ground of very dimly lit premises. The conductor is embedded in the ground and cannot be moved to be installed on movable objects to be marked.

 There is therefore a need for an economic and autonomous beaconing system which can be installed easily while avoiding the problems mentioned above.

 The present invention provides a method of coupling a light conductor with a light emitting diode in which the output face of the light emitting diode is flattened and the input face of the light conductor is machined so that the latter is practically planar and the exit face of the diode is located in register with the entry face of the light conductor, the two faces being practically parallel to one another.

 The present invention also provides a signaling system by light conductor comprising a light-emitting diode whose output face is practically planar and a light conductor whose input face is machined so as to be practically planar and is arranged opposite the flat face of the light-emitting diode.

 In an advantageous embodiment of the invention, the planar faces of the light-emitting diode and of the light conductor are kept in contact.

 Advantageously, the light conductor is a lateral light loss conductor which can have several fibers so as to provide a beacon device for dark rooms.

 In another embodiment, the means for securing the diode to the light conductor only comprises a relatively rigid element, the internal diameter of which at each end is arranged to tightly tighten respectively the practically cylindrical body of the diode and the light conductor .

 In another embodiment, the means for securing the diode to the light conductor does not include any optics and includes a light conductor holding element articulated on a diode holding element so as to be able to bring the face into contact input of the light conductor and the practically flat emitting surface of the diode.

 Other characteristics and advantages of the invention will appear on reading the following description made with reference to the accompanying drawing.

 FIG. 1 is a perspective view of equipment provided with a signaling system incorporating the invention.

 Figure 2 shows in perspective a signaling system according to the invention.

 FIG. 3 represents an enlarged and partial section of the device according to the invention making it possible to better understand the device for coupling a diode with a light conductor.

 Figure 4 shows in perspective and not assembled, another embodiment of the coupling device useful in the invention.

 FIG. 3 shows a detail of the signaling system according to the invention showing the coupling of a diode to a light conductor.

 As can be seen in FIG. 1, a material 2, such as for example raw materials placed on a pallet 3, can be temporarily stored in the vicinity of a machine located in a room in dimmed light. This occurs frequently in the premises for the production of photographic products for which the presence of a determined quantity of photons permanently modifies the product.

 In the present application, by room in dimmed light will be understood the rooms in which the illumination allows only a practically scotopic or low mesopic vision.

 To avoid accidents due to the possible presence of such equipment, it is advantageous to provide this equipment with a signaling system 10 which materializes the volume occupied by the equipment. Advantageously, this materialization will take the form of a weak light source delimiting the volume of the material. According to the invention the signaling system 10 comprises a housing 12 (fig 2) and at least one light pipe 14 with lateral energy loss. Advantageously, the light conductor 14 is formed by several fibers or fiber bundles which are arranged so as to delimit the space occupied by the material. As seen in Figure 1 the fibers 14 were arranged according to the stops of the occupied volume.

The fibers 14 can be held in place by any suitable device, for example adhesive tape.

 FIG. 2 shows in perspective a part of the signaling system according to the invention in which certain parts have been omitted or torn off for a better understanding of the invention. The system comprises a housing 12, provided with a base 16 and a cover, not shown. The base and its cover once assembled form the housing 12 which is light-tight. Advantageously, the base is divided into two compartments 18, 20 by a wall 22. One 18 of the compartments receives the energy source, such as for example a conventional battery 24 providing a determined potential, for example 3,6,9,12 or 24 Volts, and the power supply circuit of a light source 26 (fig 3) such as for example a light emitting diode. The other compartment 20 is adapted to receive a coupling device 28 (see FIGS. 3 and 4) making it possible to connect the diode 26 and the light pipe 14. Advantageously, the wall 22 serves to hold the diode 26.

Optionally, the wall 22 can be provided with an annular projection 34 surrounding the diode 26 and the utility of which will be understood below.

 FIG. 3 represents a first embodiment of a device 32 for coupling a diode 26 and a light pipe 14. According to the invention, the diode has a planar emission face 28. The light pipe 14 is machined so as to have a planar inlet face 30 which is practically parallel to the emission face of the diode 26. The coupling device 32, in this particularly advantageous and inexpensive embodiment, is obtained by means of a sleeve, one end of which 33 is adapted to fit onto the light pipe 14 and the other end of which is adapted to fit on either the support of the diode 26 or on the one protuberance 34. The coupling device 32 is made of a material having a low elasticity so as to keep the planar faces 28, 30 of the diode and of the light pipe parallel to one another and in the vicinity of one another. In a particularly advantageous embodiment, the planar face 28 of the diode is practically perpendicular to the axis of the diode and to the axis of the light beam emitted by this diode and the entry face 30 of the light pipe is practically perpendicular to the axis of the conduit.

 The optical fibers can be provided at their ends with ferrules 40 or generally metallic end cap enclosing the fiber. FIG. 4 shows another embodiment of a coupling device 32 between a diode 26 and a light pipe 14 provided, at one end, with a ferrule 40. The coupling device 32 has a stirrup 41 in the shape of a "U" coming to be fixed on a support 42. The support 42 comprises a collar 44 whose internal diameter is adapted to fit either on the support of the diode 26 or on the projection 34. After fitting, a screw, not shown, allows the support 42 to be immobilized relative to the diode 26. The stirrup 41 has on each of the branches of the "U" an oblong opening 46 making it possible to immobilize, by means of screws not shown, the stirrup 41 relative to the support 42 after adjusting the position of this stirrup. The stirrup is provided with a slot 48 adapted to receive the ferrule 40 surrounding the light conductor 14. This device 32 makes it possible to have more precisely the emission face 28 of the diode 26 relative to the face of input 30 of the light guide 14.

The electrical supply circuit of the diode 26 may include a switch making it possible to interrupt the operation of the signaling device and an adjustable potentiometer making it possible to modify the light flux emitted by the diode 26. Advantageously, access to the potentiometer is obtained by a small opening 50, which limits the possibility of modifications to the potentiometer setting by unauthorized persons. The hole can also be closed off with a rubber plug or the like in order to perfect the sealing of the housing 12. In particularly advantageous embodiments, the light-emitting diodes are diodes with caps, in this way it is easy to replace the diode and to adapt the color of its broadcast to the necessary conditions. The types of diodes which have been used are diodes manufactured by the company MARL (Great Britain). The following diodes were used: 505nm blue-green MARL LED, 20mA "flat top" type, BaS9s base, ref 215-943; Green MARL LED 525nm, 20mA "flat top" type, BaS9s base, ref 215-532 and Led
MARL yellow-orange 590nm, 20mA "flat top" type, BaS9s base, ref 215-521.

As light conductor, the following optical fibers were used: -FORETREC O F1OTR, bundle of 400 glass optical fibers, useful diameter 1 mm, sheath diameter 2.2 mm; -FIBER STARS O SS15, bundle of 14 plastic optical fibers (PMMA) with an external diameter of 7 mm, with coating delimiting luminous diamonds; -3M (e) LF90, single-strand plastic optical fiber (PMMA) with an external diameter of 11 mm. However, it is obvious that other fibers well known to those skilled in the art can be used.

 We have described the invention in connection with a particular use, it is obvious that one can use the signaling system according to the invention to mark the walls of the corridors or the openings in the partitions.

Claims (7)

 1 Method for coupling a light conductor with a diode  electroluminescent in which the output face of the diode is formed  electroluminescent so as to obtain a practically flat face, we machine  the input side of the light conductor so that it is  practically flat and we have the output face of the diode in registration with the  input side of the light conductor, the two sides being practically  parallel to each other.  2 Method according to claim 1 wherein the entry face of the  light conductor lit by the light-emitting diode in contact with the  emission face of the light-emitting diode.  3 Signaling system (10) by light conductor for rooms with lighting  scotopic or weak mesopic, using the coupling method according to one  claims 1 or 2, comprising:  a light-leaking light conductor (14) provided  a substantially planar entry face (30);  a light emitting diode (26) having an emission face (28)  practically flat;  an autonomous energy source (24) enabling the diode to be excited  electroluminescent (26); and  means (32) for keeping the inlet face opposite each other  of the light conductor and the emitting face of the light emitting diode. 4 System according to claim 3 wherein the light conductor is  surrounded by a ferrule and in which the entry face (30) of the  light conductor lit by the light-emitting diode in contact with the  emission face (28) of the light-emitting diode. 5 System according to any one of claims 3 or 4, wherein the  light conductor is a bundle of fibers with lateral light loss. 6 System according to any one of claims 3 to 5, wherein the means  to secure the light conductor to the diode has only one element  relatively rigid with an inside diameter at each end  arranged to tightly enclose a member, respectively, of a member  cylindrical (34) integral with the diode and the light conductor. 7 System according to any one of claims 3 to 5, wherein the end  of the light conductor is provided with a ferrule (40) and the means for  securing the light conductor to the diode comprises a bracket (41) for holding the light conductor, articulated on a holding element (42) fixed relative to the diode so as to be able to face the input face (30 ) practically planar of the light conductor and the practically planar emitting surface (28) of the diode.