Lighting Device for Fiber-Optic Systems

The lighting device can be better understood by examining the FIGS. 1 to 4 and their description as follows:

FIG. 1 is a schematic plan view partially in cross-section of a lighting device according to the invention.

FIG. 2 is a schematic plan view partially in cross-section of a lighting device according to the invention for lighting one light entrance end of a many-veined light guide which guide has been bifurcated into two strands to receive light from a divided beam.

FIG. 3 is a schematic plan view partially in cross-section of a lighting device according to the invention for lighting two light guides with equal intensity.

FIG. 4 is a perspective schematic view of a lighting device according to the invention for lighting of a fiber-optic digital-signal indicator by means of a many-veined light-guide.

The schematic construction in FIG. 1 shows an upper light source 8 consisting of a lamp 1 and a focus means 2 consisting of a concave mirror 15 and condenser lens 16. Correspondingly there is a lower light source 8' with lamp 1' and focus means 2'. The optical axes 17 and 17' of both light sources make a 90.degree. angle with each other. At 45.degree. to the optical axes 17, 17' of the light sources 8, 8' is a beam-splitting mirror 3 which is so arranged that the crossing point 18 of the optical axes lies in the plane of the beam-splitter 3. Along the length of the optical axes 17, 17' of the light sources 8, 8' beyond the beam splitter 3 is found the entrance ends 4 and 4' of one or two multi-veined light guides 19 and 19' respectively. These entrance ends 4, 4' can be connected for selective application to color filters 7 and 7'. The constructions designated 5 and 6 show automatic controls for lamps 1 and 1' which can be, for example, a brightness regulator or switching control as previously discussed. The hatching marks for the light beam as shown for lamp 1 indicates that this lamp is in operation while the dotted line around the beam means that lamp 1' is not in operation.

From the focus means 2 the beam from lamp 1 goes through the beam splitter 3 where it is divided into two segments, one which passes through the beam splitter 3 and continues in generally the same direction and enters into the light guide 4 and the other beam segment is reflected and enters into light guide 4'. In using lamp 1' the beam is similarly divided into two corresponding beam segments. It is not possible to know from observing the beam segments from which lamp the light is coming. By using both lamps together the beam segments can be made to overlap so that each of the light-guide entrances 4 and 4' receives practically the same amount of light as with using one lamp with the beam splitter 3 removed. The only decrease is caused by the absorption loss occurring at the beam-splitter 3.

In the arrangement according to FIG. 2, two light sources 8 and 8' are shown, which are drawn to indicate that an elliposidal mirror 20, 20' serves for focusing the light. The beam segments generated through the beam splitter 3 enter into the entrance ends 9' and 9" which in turn are divisions from a multi-veined bifurcated light guide 9.

Each single fiber according to the arrangement of the invention transports the same amount of light, independent of whether the fiber empties into entrance ends 9' or 9" and independent of whether the light source 8 or 8' is in operation. Thereby the joined light guide 9 carries the full illumination of whatever lamp is switched on to wherever it is desired.

FIG. 3 shows an arrangement, which differs from FIG. 2 only in that the lighting device according to the invention consists of the light sources 8 and 8' arranged so that beam segments from the beam splitter 3 light two separated light guides 10 and 11 and these light guides are not led or joined together. The ends of these separate light guides are intended for illumination at two different places. Such devices find application, for example, in medical use.

In FIG. 4 is shown the application of the device according to the invention in the area of indicators. A multi-armed light guide 22 is at its end divided into a large number of individual strands 14, and each strand leads to a grating hole 21 of a signal board 13. The entrance end of the light guide 22 is joined together to two strands 12 and 12' which are lighted according to the invention. In this example it is especially clearly affirmed that in spite of the divided entrance, all fibers 14 transport the same amount of light, for the individual grating holes 21 of the lighted numbers show the same brightness. While the graphic drawing shows the individual arms 12 and 12' of the light guide 22 somewhat spread apart, it basically applies to any multi-armed light-guide, the light from which might be extinguished at times by a light source failure. A lighting device according to the present invention as illustrated in FIG. 4 would avoid the reproduction of maimed or curtailed figures or numbers due to the failure of a single light source.

Connecting color filters into the system makes the reproduction of multi-colored designs possible.

Further possible applications suggest themselves for the areas of light-bodies for punch cards and light barriers in which the light-transmitter utilizes fiber-optic elements. Here, as in all cases in which light is transmitted through fiber optic systems, a very high degree of reliability is necessary.

Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described above and as defined in the appended claims.