US2109990A - Luminaire - Google Patents

Description

March 1, 1938. H. J. FLAHERTY LUMINAIRE Filed June 26, 1936 sumac/0A1. V

PARA 90.410041.

Irwverwtorr Harold J. Flaheftg. by fi w/j w 7 Hi Attorrweg.

Patented Mar. 1, 19 38 LUMINAIBE Harold J. Flaherty, Scum, Mara, gnor to General Electric Company, a corporation of New York Application June 26, 1936, Serial No. 87,470 4 Claims. (01. 240.-2 5) My invention relates to luminaires, and more particularly to street-lighting luminaires.

One object of my invention is to provide an improved reflector whereby a substantially uni- 5 form distribution of light may be obtained over a predetermined area.

For a better understanding of my invention, together with other and further objects thereof, reference is had to the following description.

it) taken in connection with the accompanying drawing, andits scope will be pointed out in the appended claims.

In the accompanying drawing, Fig. 1 is a vertical cross-section view of a luminaire equipped ill with my improved reflector, and Fig. 2 is a -par--. tial view of a modified luminaire also equipped with my improved reflector.

In the luminaire of Fig. 1, a light source I, such as an incandescent filament lamp, for ex- 20 ample, is the light source'and is supported in a socket 2, which in turn is mounted in a porcelain cap 3: A conductor 4 conducts current tothe terminals of the socket 2 through a receptacle 5.

The light source is enclosed by a housing com- 25 prising a sheet metal reflector I and a glass globe 8. The reflector is provided at its lower end with a flange 9 which is preferably spun over the edge of the globe 8 for the purpose ofproviding a dust-proof joint between the reflector and globe.

30 The housing is attached to the cap. by means of latches comprising rings l engaging lugs II on a metal collar l2 surrounding the cap 3 near its lower edge. This collar I2 is provided with a' cap 03 by means of whichit may be attached to any 35 convenient pipe and thereby support the entire unit. 7

In luminaires of the type disclosed, the reflector is designed to collect substantially all light projected by the source above the horizontal and to 40 reflect it towards the surface over which it isv suspended. The difllculty has been to distribute the reflected light in such manner that when the.

reflected light is combined with the direct light from the source, a uniform intensity is obtained 45 over the entire area. In view ofth high intensity of the direct light, directly below the luminair, it becomes necessary to project practically all the reflected light to the edge of the illuminated area. This has been impossible with 50 the conventional continuous surfaced reflectors having the conventional curvatures and dimen-,

sions. The main reason for this limitation is that only a comparatively narrow section of the reflector surface could be used to reflect light at 55' the-angles nearest to horizontal. The light reflected from the sections of the reflector nearer to the zenith are reflected at such low angles that the light strikes the surface near the luminaire where it raises the light intensity above the desired value, or it strikes the opposite edge of the reflectorthereby being confined within the reflector. In accordance with my invention the surface of thefreflector is given a curvature such as to project the maximum of light to the edge of the beam and a supplementary surface con- 10 focal with the continuous surface is provided to project additional light towards the edge of the beam. Y

The reflector in. the illustrated luminaire is a surface'of revolutioncomprlsing a paraboloidal surface having its axis tilted to the horizontal by abont 1 5. The axisof this section of the reflector is indicated by a line H. The section ex- -tends between flange 9 and a line indicated by point ii. in the drawing. This reflector section projects a parallel beam bounded by the lines l6 and ll. Line It represents the upper edge of this beam and indicates that it passes under the opposite edge of. the .reflector. The resulting beam from thissection of the reflector surface is a conoid .with its apex at the center It of the light source I. 7

"It isevident that if the paraboloidal surface were continued above the indicated line l5, the light a'boire that line would be cut of! by the opposite edge of the-reflector. A greater proportion of the upwardly'projected light, therefore, cannot be projected by a paraboloidal section without changing the angle of the axis l4 or increasing the diameter of the reflector. A partial solu-' tion of this problem is obtained by continuing the surface of the reflector as an ellipsoid having its conjugate feel at the center I! of the light source and at a point l9 which is below the edge of flange 9; and outside of the-glass globe 8. This surface 40 extends from the. edge l5 of the paraboloidal section' up to a line 20. This surface is extended as far as possible upwardly toward the zenith without projecting light against the flange 9. The

light from this reflector section is concentrated at the locus of foci l9 and is then added to the light projected by the paraboloidal section. The surfaces so far described still leave a large portion of the upwardly projected light unreflected. A continuation of the ellipsoidal surface would partially take care of this problem, but that would result in an increase of the length of the luminaire. or would necessitate an increase in diameter. This is undesirable.

In accordance with my invention, I terminate ellipsoidal reflector 2|, confocal with the upper section of the main reflector, but having shorter flector 2| is illustrated as being concentric with the main-reflector I and having an average diameter which passes its reflecting surface from the main reflector surface toward thecommon axis. The main reflector is provided with a reducing flange 12, towhich the rings III are fastened, and

also a collar 28. The collar 28 is concentric with the main reflector and projects above the flange 22 into the lower end of cap 8. The second reflector 2i is provided with a collar 24 which projecting above the reflector, fits inside of the collar 23 and thereby supports this flector.

The reflector 2|, as stated above, is ellipsoidal and is confocal with the main reflector surfaces. It extends into the main reflector between the surface of this reflector and the axis thereof so as to intercept a substantial portion of the light from the source projected between the upper edge 20 of the main reflector and the edge of socket 2. With this complementary reflector, I am, therefore, able to intercept, nearer to the source, and reflect into the beam reflected by the main reflector a substantial portion of the upwardly projected light at the greater angles, that is, light projected nearer to the vertical axis and I am able to do this without an increase in thesize of the reflector. 4

In Fig. 2 I have illustrated a modiflcationof the porcelain cap 3. In this modification the porcelain cap 25 is made larger so as to accommodate a supporting collar 26 above a rain shield 21. A beading 28 prevents the cap from slipping out of the collar. A metal adapter 20 is held into the. lower end of the cap by screws 30 and the reflector I is attached to the adapter by ring latches iii, the same as in Fig. 1.

The glass globe 8 may be made of any suitable glass and shape. In Fig. 1 I have indicated diffusing prisms ll on the outer surface of the globe. Any suitable prism may be used for diifusing and refracting light on either the inner surface or the outer surface thereof.

What I claim as new and'desire to secure by Letters Patent of the United States is: I

complementary rethe ellipsoidal surface, thereby creating in effect, a complex frustro-conoid and provide a second I 1. In a street-lighting luminaire, the combination of a main reflector, a light source, and .an auxiliary reflector, arranged within said main reflector to intercept light outside of the collecting angle of said main reflector and toreflect said light into the beam projected from said first reflector, said first reflector having a focal point at the center of the light source and a second focal point outside of said reflector, said auxiliary reflector having foci coinciding with said foci of said first reflector but having. at least one of its corresponding focal lengths shorter than that of the first reflector.

2. In a luminaire, the combination of a frustroconoidal reflector comprising a surface of revolution including a paraboloidal and ellipsoidal surface joined end to end, and a complementary reflector comprising an ellipsoidal section mounted within and concentric with said main reflector outside of the collecting angle of said first reflector and provided with a surface confocal with said first ellipsoidal section but having at least one shorterv focal length than the corresponding focal length of said ellipsoidal section.

3. In a luminaire, the combination of a lamp, a socket therefor and a frustro-conoidal reflector comprising a surface containing an ellipsoidal and a paraboloidal section arranged to form a continuous surface, and a second reflector comprising an ellipsoidal flange concentric withsaid reflector, said flange being confocal with the said ellipsoidal section of said continuous surface and arranged to intercept an arc of the projected light extending from the upper edge of the main reflector and toward the axis of said main reflector and projected into the main beam below the edge of the lamp socket.

4. In a luminaire, the combination of a light source, a reflector comprising a surface of revolution having an axis projecting through saidlight source and including an elliptical section, the axis of said ellipse being at an angle to the axis of the surface of revolution and the'conjugate foci ,of said section being respectively at the center of said light source and outside of said reflector, and an auxiliary reflector confocal with said section having at least one shorter focal length arranged to intercept light between the edge of said elliptical section and the axis of said surface of revolution.

HAROLD J. FLAHERTY.

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