RAILROAD SIGNAL HAVING LIGHT PIPING FROM SOURCE MOUNTED AN EXTERIOR OF REFLECTOR CONE

• US 3,576,563 A
• Filed: 05/20/1968
• Issued: 04/27/1971
• Est. Priority Date: 05/20/1968
• Status: Expired due to Term

• Current Assignee: Harrison A. Scott, James E. Moe
• Original Assignee: Harrison A. Scott, James E. Moe
• Inventors: Scott, Harrison A., Moe, James E.
• Application Number:
  US04/730,482
• Time in Patent Office: 1,072 Days
• US Class Current: 385/115
• CPC Class Codes: B61L 5/1827 using light sources of different colours and a common optical system

Abstract

A railroad signal has separate light sources for each of the separate colors employed, such as red, yellow, and green or other standard colors. The light sources are located away from the external lens of the signal unit, and are housed deep within the metal casing in order to protect them from vandalism. Yet no mechanical motion at the light source is required to switch the signal from one color to another; instead the switching is done electrically by means of relays in the conventional control circuitry which select one of the alternative light sources for energization. The light from all three lamps, red, yellow and green, is brought together by fiber optic bundles so that it emerges through a single external lens in an unusually bright, concentrated beam which is aimed down the right of way. A sighting tube is provided, as is test apparatus for adjusting the sighting tube to achieve precise alignment of the signal relative to the direction of the railroad track.

Claims

1. A high-efficiency railroad signal comprising a plurality of sources of light beams of different colors, means providing a common axis egress from said railroad signal for said differentcolored beams, and a light pipe including branches having entrance ends positioned for capturing respective differentcolored light beams and combining into a common trunk having an exit end positioned to direct all of said different-colored light beams to said common egress, said light pipe being a fiber optic bundle comprising a plurality of discrete light-conducting fibers of a first material individually coated with a second material of a differing refractive index to produce total internal refraction at the interface between the materials, a different group of fibers originating from said common trunk and diverging therefrom to form each of said branches.

2. A high-efficiency railroad signal as in claim 1, wherein the fibers in each branch are continuous and uninterrupted by reflective end faces over their entire length from the entrance end of each branch to the exit end of said common trunk whereby to achieve maximum light transmissivity.

3. A high-efficiency railroad signal as in claim 2, wherein the fibers from each of said branches are distributed over said exit end of said common trunk whereby to achieve substantial homogeneity of the signal beam regardless of color.

4. A railroad signal comprising a housing formed with an opening to allow a light beam to exit therefrom, a supporting cone having an opening at its apex and an opening at its base, said cone being mounted with said base in surrounding relationship to the opening in said housing, a lens mounted over said opening and cooperating with said cone substantially to enclose the interior thereof, at least one light source supported on the exterior of said supporting cone, and a light pipe arranged to convey light from said source to said apex opening.

5. A railroad signal as in claim 4, including means for focusing the light from said source upon the adjacent light pipe end.

6. The railroad 5, defined in claim 5 wherein said light-focusing means include an ellipsoidally shaped reflector and a light source positioned substantially at a first focus of the ellipsoidal reflector, with the input end of said light pipe being positioned at a second focus of the ellipsoidal reflector.

7. The railroad signal defined in claim 6, wherein the light pipe is formed with a plurality of tributary input branches converging to form a common output end, and with a corresponding plurality of different-colored light sources and associated focusing means each optically aligned with the input end of one of said tributary input branches.

8. A railroad signal comprising:

A. a plurality of light sources;

B. means for focusing the light from said sources so as to provide a minimum size image of each light source;

C. respective different color filter means interposed between each source and its image;

D. corresponding plurality of branch fiber optic bundles each having an input end cylindrically encased in a relatively rigid material positioned so said image falls upon said cylindrical input end;

E. means engaging said rigid material to secure said branch bundles in place in relation to said images;

F. said branch bundles being continuous and converging into a common trunk bundle;

G. said trunk bundle terminating in an output end for delivering light from each of said sources;

H. means for collimating the light delivered by said trunk bundle end;

I. said trunk bundle end being cylindrically encased in a relatively rigid material;

J. means engaging said rigid casing to secure said trunk bundle end in position relative to said collimating means.

9. A railroad signal as in claim 8, wherein:

A. said branch bundles curve from said light sources to the place where they combine into said trunk bundle; and

B. a flexible protective coating covers said fiber optics between said rigid casings to permit flexing of said branch bundles for ease of installation in said railroad signal.