US2190526A - Light signal - Google Patents

Description

W. B. WELLS Feb. `1.3, 1940.

LIGHT SIGNAL Filed Aug. 6, 1938 Sandblafed PdlhfedPea.

INVENTOR LI/@JZey wem/n BY- 44; H15

ATTORN EY Patented Feb. 13, 1940 LIGHT SIGNAL Wesley B. Wells', Wilkinsburg, Pa., assignor `to The Union Switch & Signal Company, ,Swissvale, Pa., av corporation of Pennsylvania Application August 6,1938, serial No. 223,467 i 1 claim. (o1. 4ta- 133) `My invention relates to light signals. One object of my invention is to provide a light signal having a legend or the like which is visible vwhen and only when the'signal is illumi-y hated. 4

Anotherobject of my invention is to provide a light signal the energy requirements of which are a minimum, and which when illuminated is capable of displaying an indication which is clearly `visible by daylight under 'the most unfavorable conditions oflight and background.

Other objects and characteristic features of my invention will appearas the description proceeds.

I shall .describe one form of light signal embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanyingdrawmg, Fig. 1 is averti cal longitudinal sectional View showing one form of light signal embodying my invention. Fig. 2

is a front View of the signal vshown in Fig. 1.`

Fig. 3 is a front View of a stencil forming part of the signal shown in Figs. 1 and 2,. Fig. 4 is a iront view of a modied form of stencil which may be used in the signal shown in Figs. 1 and 2.

Fig. 5 is a front view of a screen structure forming part of the signal shown in Figs. 1 and 2.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Figs. land 2, thesignal comprises a housing I provided with a hinged iront door 2 having an aperture 3. Located in the housing 'I are light projecting means comprising a parabolic reector 4 and an electric lamp 5l having its lament located at the focal point of the reliector 4.' The lamp 5 is supported by a suitable bracket I5 secured to the housing I, and the lamp reflector is so arranged that when the lamp is illuminated, a beam of substantially par. allel rays will be projected toward the aperture 3. Operating current for the lamp 5 is supplied by through a suitable aperture 8 formed in the top wall of the housing.

The door 2 is formed with a tubular portion III provided at its outer end with an inwardly ex tending annular flange II which defines the aperture 3, and mounted within this tubular portion between the flange. I I and suitable clips I2 which are secured.` to the door by means `of screws I3 a pair ofwires 'I which extend into the housing I l are ay convex cover glass I4 and a convex stencil I5 separated by a screen structure I6.

The stencil I5 may be formed in a variety of ways to provide the desired signal indicia which, in the particular signal illustrated, constitutes letters grouped into words to form the legend No left turn. For example, the stencil may be` made of sheet metalwth theletters cut out as shown ,in Fig. 4, or it may comprise a piece o1 glass painted or otherwise coated to form con- T trasting light and dark areas as shown` in Fig. 3. In this latter case, the stencil will preferably bev made from clear glass and the area around the letters will preferably be painted white due to the ability of white paint to reilect light back-{1,}` l0` towards 'the reflector, where it will again be reected forwardly by the reflector so that a portion of this twice reflected light will find its way through the clear letters of the stencil and thus strengthen the indication. `It should be pointed out, however, that colors other than white may be used to` provide the contrasting light anddark areas, and that a satisfactory indication can `be obtained by painting the letters on either the inner or outer face or both of a clear glass stencil. In cases where the maximum signal`ey i ciency is desired with a minimum expenditure of energy, the stencil may have that portion of its inner surfacewhich surrounds the areas which 't form the signal indicia coated with a light re? ecting medium suchv as silver, and the stencil may further have the same shape as the reector and may be positioned in front of the lamp filament the same distance as the reflector, whereby the stencil itself will act as `a reector the `focal point of which is disposed at the light lament. With this last mentioned construction which is the construction shown in Fig. 1, the body ofthe stencil may comprise clear glass or it may consist of metal with areas cut out to form the desired signal indicia. It willbe noted `that when` the stencil is constructed to act as a reilector, a portion of the light from the lamp will'pass directly through the letters,` and 'another portion will be reected by the back reflector in parallel rays 'someof which will pass through the letters, while still other portions will strike the stencil and will be reflected back through the focal I pointto the rear reector whereA it will again be reflected forwardly in parallel rays to cause a portion of this light to pass through the letters and strengthen the indication. This latter procedure would be repeated zuntil all light had passed through the stencil or had been absorbed by the two reflecting surfaces.

The cover glass I4 serves to close the aperture 3, and has its inner surface sandblasted toprovide some spread to the signal indication, and

also to assist in obscuring the legend when the signal is not illuminated.

The screen structure I5 may be similar to that described in Letters Patent of the United States No. 1,806,051, granted to Arthur W. Fisher and myself on May 19, 1931, for Light signals, and comprises briefly a corrugated strip of opaque material spirally wound Within a strip of opaque ilat material to form a plurality of cells having their axes parallel to the rays of the beam projected by the reflector 4. It follows that the rays of light projected through the -stencil will pass through the screen structure l Without interference, but that rays of light from lan exterior source falling upon the screen structure Will be absorbed and Will be prevented from giving a phantom indication. Without this screen structure,A the signal legend is Visible when the lamp is not illuminated, even though the rear surface of the front cover glass is sandblasted.

A hood i8 of the usual construction is secured to the door 2 above the cover glass M to protect this cover glass from the direct rays of the sun.

It should be particularly pointed out that While in describing myl invention I havev shown the stencil l-provided with the legend No left turn, this rstei'icil may beprovided with any other desired 4signal indicia such as the legend"No right turn, Tvvo trains, Stop, Walkf, etc.

AlthoughI have herein shown and described only oneform of light signals embodying my invention, itis understood that various changes and modifications'may be made thereinv Within the scope of the appended claim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

A light signal comprising a casing provided with a front door having an aperture, a source of light in said casing, a parabolic reflector in said casing for projecting a beam of substantially parallel rays toward said aperture, a cover glass mounted in said door and closing said aperture, a stencil mounted in said door between said cover glass and said source and having light transmitting and non-light transmitting portions arranged to form signal indicia, said stencil having the non-light transmitting portions of its surface on the side adjacent to said source provided with light reilecting means'and being shaped similar to said reflector and being so positioned that its focal point Will be disposed at said source,vvhereby said'stencil acts partly as a reector to improve the elciency of the signal, and a screen structure disposed between said stencil and said cover glass and arranged to permit light rays from said beam to emerge from the signal but to prevent light rays entering the signal through said cover glass from rendering said signal indicia Visible, the inner surface of said cover glass being roughened to add some spread to the signal indication and to assist iny rendering the signal indicia invisible due to extraneous light.

f WESLEY B. WELLS.

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