Illumination – Light fiber – rod – or pipe
Reexamination Certificate
1999-08-06
2003-07-15
O'Shea, Sandra (Department: 2875)
Illumination
Light fiber, rod, or pipe
C362S552000, C362S583000, C362S559000, C362S259000, C385S093000, C385S901000
Reexamination Certificate
active
06592245
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to a method for optically marking an elongated indication path, especially useful for Intelligent Transport Safety (e.g. known in short as ITS) signs, signals or trance uniform illumination wherein light is delivered or distributed in a trance uniform flux density). More specifically the present invention relates to supporting a light guide (e.g. light conduit, liquid light guide, photon guide/s, fiber or fiber bundle/s) along an indication path, and aligning an end of the light guide with (a light source or a plurality of light source's output/s) an optical light socket wherein the light guide is characterized by having at least one side emitting optic fiber within a flexible (holographically grooved grated tube) semi-opaque sleeve. The present invention also relates to devices using the method for optically marking an elongated indication path of the present invention.
BACKGROUND OF THE INVENTION
Outdoor signs and signals (as used in transportation and advertising) are often integrated with an illumination mechanism. The illumination mechanism allows the signs and signals greater visibility, especially at night (or during reduced visibility due to whether conditions such as fog, storms, rain, winds, dust, smoke). The illumination mechanism is often by external lighting sources from the front, or from the rear through semi opaque sections. Another well known illumination mechanism is by incorporating light sources into the surface of the sign (or signal). Regardless of the location of the light sources, each such source requires individual electric circuitry (and individual optical alignment or housing as well as subsequently individual maintenance).
According to any of these well known methods of illumination, the optical marking of an elongated indication path is prohibitively expensive and cumbersome because a large number of light sources are required, these well known methods include serial connection of a plurality of light sources (e.g. each light source is aligned to single light guide, fiber, or light conduits or lens or signs and signals) without the ability to efficiently combine their collective outputs for long distance high intensity optical marking or illumination, Thus use of elongated illumination paths have found only limited uses in critical applications (such as highlighting air transport runways, oceanographic optical marking or illumination systems or ITS type systems (e.g. Intelligent Transport Systems—optical traffic warning signals) lighting systems and/or efficient light distribution fiber networks for optical marking or illumination).
As a practical alternative retro-reflective materials (such as paints and corner cubes) have found wide application. The specific limitation imposed by using retro-reflective materials (in place of elongated illumination paths) is that only the specific illuminated area of the retro-reflective material is highlighted for the observer's attention. The observer fails to become aware of the extent of the elongated marking by reason of his use of a limited source of illumination, or by his lack if having any illumination source. For example, the placement of retro-reflective paint on the road side only provides a night driver with indications of the road path (curvature) within the distance of his head lights' illumination. Obviously retro-reflective materials can not be used as ground markers for distant observers who may be in the air or at sea, because such observers can not practically provide a powerful source of wide angle illumination. Retro reflective materials also are subject to environmental deterioration, and also often accumulate obscuring layers of grime and mud.
Various methods and devices for Illuminating elongated paths by various methods of optic fibers arrangements are known. For example, such arrangements are disclosed in U.S. Pat. No. 5,333,228, FR 2711249, U.S. Pat. No. 4,422,719, U.S. Pat. No. 4,740,870 and WO 92/09909. All these devices, however are limited to a short distance illumination and to a single light source.
In contrast to the prior art, the method (and devices) of the present invention provides for the cost efficient optical marking or illumination of elongated indication paths. The cost efficiency associated with the present invention is derived from the lower costs of installation, operation, and maintenance of a central light distribution points which harnesses the collective optical outputs of a plurality of light sources providing for (adequate resolved or pre-mixed or post mixed light distribution) the flux density of the delivered light to be equalized and simultaneously broadly distributed spatially in a trance uniform manner (e.g. uniformly) using interconnected sections of optical fibers (or fiber bundles). To further appreciate the un-obviousness of the present invention, a brief introduction to technological aspects of certain critical components is hereinafter appended:
Optic fibers are commonly made of glass and glass-like materials. There are two well known types of optic fibers; end emitting and side emitting. End emitting optic fibers have found wide application as an efficient (low loss) long distance transmission medium—primarily for optical data related signals. Side emitting optic fibers have only found limited use as a short distance transmission medium, by reason of their low efficiency (high loss). Further more, Plastic Optical Fibers (e.g. known in short as POFs) have found limited uses in optical marking & illumination as a result of their low resistance to temperature changes (e.g. they melt or deteriorate in performance as a result of the high temperatures generated by the use of high intensity light source/s), Plastic Optical Fibers also demonstrate a much lower environmental durability (e.g. POFs can not withstand high photo-degradation levels associated with prolong exposure to sun-light) this limits the optical intensity that can be introduced to illuminate such (thermoplastics) POFs fibers as it require the introduction of expensive collimating lenses which further decrease the efficiency (flux density) of light they generate.
The present invention discloses a novel application methodology wherein side emitting fibers are used (single fiber or multi tail fiber bundles). By aligning the end of a side emitting optic fiber with a light source (or a plurality of light sources collectively harnessed to a light socket output alignment shunt/s), the transverse distribution of light along the length of the fiber provides a beneficial (e.g. uniformly or often homogeneous) illumination mechanism when the flux density of the delivered light is equalized and simultaneously broadly distributed spatially.
Optic fibers are commonly bundled into a light guide by placing a plurality of such fibers within a flexible sleeve or tube. The sleeve serves as a holding mechanism for the bundle (allowing convenient installation), and simultaneously protects the fibers from environmental damage (such as from moisture or sun light). When used as a transmission medium, the sleeve is holographically grooved to allow adequate spectral distribution for the purpose of optically marking (or high-lighting) an elongated indication path.
It must be recognized that many types of side emitting optical fibers have been suggested for the optical marking of elongated indication paths (even for transportation signs and signals). While these fibers operate well in the laboratory and in exhibitions, these fibers fail to provide the desired illumination when installed in the field. This is because the field is a harsh environment (for exposed optical fibers), having temperature extremes, and having long term exposure to mud, sun, grime, smog, depositions, molds, bacteria, wind born abrasive particles, etc. It must also be recognized that conventional sleeving (or cladding or sheathing) of optical fibers is a known art generally used to protect end emitting communication related optical fibers such as optical data transfer
Ende Michael
Tribelsky Zamir
DelGizzi Ronald E.
O'Shea Sandra
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