Illumination system which reduces loss of visibility caused by lamp failure

DETAILED DESCRIPTION It is therefore an object of this invention to provide an improved means of minimizing the loss of visibility resulting from the failure of one or more light sources in a lighting system.
These and other objects of the invention are achieved in a system which includes a plurality of light guide sections and illuminating couplers, in which the illuminating couplers provide light which is distributed by the light guides, and the illuminating couplers also transfer light between the light guide sections they couple.
It is therefore a property of the invention that some of the light from any given illuminating coupler will travel throughout all of the sections of light guide so that visibility loss due to lamp failure is substantially reduced.
In general, such a system may include three or more light guide sections, and two or more illuminating couplers, in which at least one end of each light guide section is connected to the end of at least one other light guide section by at least one illuminating coupler and each illuminating coupler connects the ends of at least two light guide sections.
Each illuminating coupler incorporates a first means for directing light emitted therefrom into the end of at least one of the light guide sections connected by the coupler.
Light which is directed into a given light guide section is conducted along that section and partially transmitted to the coupled end of each such section.
The illuminating couplers have the property that such light emanating from the end of one or more of the light guide sections connected by such couplers will be directed into the end of at least the one light guide section connected by the same coupler into which the first means directs light.
The illuminating couplers may contain electric lamps and reflectors for directing light into light guide sections, or may contain a means for redirecting light from an external source into light guide sections.
The means for transferring light from the end of one light guide section to the end of another light guide section may be a light guide within the illuminating coupler or may result from the geometrical configuration of the reflectors which direct light into the light guides