Illumination – Light source and modifier – With sealing means or artificial atmosphere
Reexamination Certificate
2001-06-08
2003-04-08
O'Shea, Sandra (Department: 2875)
Illumination
Light source and modifier
With sealing means or artificial atmosphere
C362S580000
Reexamination Certificate
active
06543908
ABSTRACT:
TECHNICAL FIELD
The invention concerns a submersible light generator with an impermeability protection index (IP) of 68 for glass or plastic optic fibers.
BACKGROUND ART
Impermeability with a protection index of 68 is defined in norm EN 60 598 1. In brief, the term submersible light generator with an impermeability protection index of 68 refers to the fact that the light generator can be submerged and function properly at a water depth of 20 meters, possibly at even deeper depths in some cases. An impermeability protection index (IP) of 68 means that it is impossible for dust and fluid to penetrate the apparatus or parts of the apparatus having such an impermeability performance.
Lighting by means of glass or plastic optic fibers, usually using plastic optic fibers, such as methyl polymethacrylate, is becoming more and more common.
In the most important applications, such as in the fields of signaling, beaconing of ways, rails and car parks, industrial and road lighting, security and building lights, researches are currently made to improve light generators for optic fibers with the aim of achieving the following results:
the possibility of placing light generators in areas susceptible to flooding or under water;
the use of light generators with high internal thermal dissipation allowing the temperature to be reduced at the inlet of optic fiber cables or beams. Indeed, plastic optic fibers, generally made of methyl polymethacrylate, cannot withstand sustained high temperatures in excess of 80° C.;
development of light generators whose noise level, mainly because of the ventilation systems, is reduced to the maximum.
Light generators for use in optic fiber lighting systems are now commercially available but none of them has, in the present state of the art, all the properties listed above, especially impermeability defined by a protection index of 68 under a water depth of 20 meters.
Currently available generators generally consist of a metallic iodide or xenon halogen lamp, combined with a reflector which reflects light after it has passed through an appropriate focusing optic system in the direction of the beam or cable of optic fibers in charge of transmitting light in one or several points to the desired location. One of the major disadvantages of these generators is that it is difficult to obtain the best compromise between the intensity of light transmitted by the cable and the increase in temperature at the cable inlet. This can lead to the deterioration of plastic optic fibers due to temperatures they could be exposed to, which can exceed 80° C. This is why these generators have to be fitted with heat filters which, in addition to infrared radiation, absorb a significant part of visible light.
To avoid the risk of aging of plastic fibers, a W (ultraviolet) filter is sometimes necessary.
One or more ventilators are also needed to evacuate heat generated inside such generators. These ventilators give rise to a number of problems. Firstly, they are a source of unwanted noise, particularly inconvenient in some applications, because of the openings and air vents provided on some sides of said generators. Secondly, these generators cannot be used in very humid environments where there is waterstreaming or flooding. Furthermore, these openings and vents often allow some of the light fog emitted by the lamp to pass through, thus creating an undesirable light fog.
DISCLOSURE OF THE INVENTION
The present invention concerns a light generator for plastic or glass optic fibers which can function equally well in air and underwater, and which can be submerged to a depth of 20 meters, possibly more in some cases.
This invention also covers a light generator for plastic or glass optic fibers which makes it possible to have a temperature at the inlet of optic fiber cables or beams which is low enough to prevent degradation by fusion of the optic fibers, especially when these are made of plastic.
The invention also concerns a submersible light generator with an impermeability protection index of 68, for glass or plastic optic fibers, wherein:
a) the generator comprises several impervious modules, these modules being thermally separated and insulated from each other, but connected to each other in an impervious manner,
b) the basic modules of a light generator are:
at least one impervious module, the lamp, comprising at least one lamp sending at least one light beam over at least one focusing optic system, the lamp module being connected in an impervious manner to an electric energy source,
at least one impervious module, the transfer module, which receives the light beam leaving the lamp module, where one of the lateral sides of the transfer module is close to one of the lateral sides of the lamp module, the passage of the light beam taking place across two sealed windows made of an optically transparent material, positioned opposite each other respectively in said lateral sides of the lamp and transfer modules, the transfer module having on another side thereof a connector for a set of optic fibers conducting light generated by the generator, in the form of a beam of optic fibers or an optic cable;
c) between the lateral sides of the lamp and transfer modules facing each other, outside the zone provided for the passage of the light beam which is delimited by the two sealed windows, means are provided to ensure the impermeability IP 68 of the lamp and transfer modules with the external environment, which take into account the thermal expansion and the thermal shrinkage of materials, and means to thermally insulate these modules from each other.
To this end, a first seal, a thermal insulator and a second seal, which fulfil the above-described functions, are included, preferably successively;
d) the other sides of the lamp and transfer modules are made of a good heat conductor material and, when these sides constitute part of the external sheath of the light generator, these sides are configured to have the largest thermal exchange external surface in contact with the external environment and an internal surface in contact with the internal atmosphere of the modules allowing optimum heat transfer towards the outer surface.
Within the scope of this invention, the term “impervious” will be used to define elements having an impermeability protection index IP of 68.
Preferably, the impervious and thermally insulating separation provided between the lamp and transfer modules, which comprises an impervious and optically transparent passage of the light beam, is comprised of:
a plate made of a porous, mineral or organic material whose porosity has been blocked by soaking in a glue under vacuum, for example epoxy resin-based glues such as those sold under the brand name Araldite.
The thickness of the plate varies and depends on the thermal conductivity coefficient of the porous material. Plate thickness is advantageously equal to at least 5 mm and varies preferably between 5 mm and 20 mm.
Good results have been obtained with a plate made of a composite material sold under the brand name PAMITHERM:
which consists of sheets of mica with a high granulometry, soaked in a silicone resin with high thermal properties: thermal conductivity according to norm DIN 52612 equal to 2.10
−3
Watt/cm.° K., average coefficient of lineic thermal expansion according to norm USM 77110 equal to 9.10
−6
° K.
−1
, good fire resistance, MOFO classification according to norm NF 16.101,
which porosity has been blocked with the aid of an epoxy resin having a thermal stability greater than 200° C. in accordance with norm ISO 75.
and two seals provided on either side of the plate and which are compressed against the plate in the course of assembly and mechanical clamping of the lamp and transfer modules to each other.
Each seal can be either flat or ring shaped. Advantageously, each seal is silicon-based because of silicon's good resistance to humidity, to high temperatures and to chemical agents, and because of its elasticity and antirot nature.
To allow the passage of the light beam, as well as the pa
Chenet Pierre
Gerbeaux Jean-Michel
O'Shea Sandra
Optectron Industries
Sawhney Hargobind S.
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