Luminaire

Feb. 24, 1948,

A. DE BISHOP, JR LUMINAIRE

Filed Feb. 24, 1944

2,436,635

Sheets-Sheet 1

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INVENTOR

Arthur DeBishop Jr.

'BY

4ρ· tLiVii/ attorney

Feb. 24, 1948. a. _DE bishop, jr 2,436,635

LUMINAIRE

Filed Feb. 24, 1944 2 Sheets^Sheet 2

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Patented Feb. 24» 1948

2,436,635

UNITED STATES PATENT OFFICE

2,436,635 LUMINAIRE Arthur De Bishop, Jr., Southington, Conn,, mrignor to The Doane Products Corporation, Meriden, Conn., a corporation of Connecticut

Application February 24,1944, Serial No. 523,621

The present invention relates to luminaires and Is more particularly directed toward direct lighting luminaires employing superposed fluorescent lamps received between downwardly acting reflectors, and these luminaires preferably have luminous side walls.

The present invention contemplates fluorescent lighting luminaires wherein the lamps are in pairs and one above the other and received in open mouthed reflectors such that except for reflection losses all of the light emitted by the lower lamp and the half of the upper lamp below the center of that lamp escapes out of the mouth of the reflector as direct or reflected light, while the light originating in the upper part of the upper lamp is largely utilized for either lighting translucent side walls of the luminaire or for indirect lighting.

The present Invention relates to improvements over the luminaires of Doane Patent 2,240,179.

Where the invention is embodied in two-lamp luminaires it is contemplated that the luminaires will be symmetrical with respect to a median longitudinal plane through the centers of the lamps and the reflectors terminate at or close to the plane through the center of the upper lamp. Such a construction uses less material than that of the former patent in luminaires of a comparable lamps size and has a well controlled dominant output for direct lighting and either an in- ⁸⁰direct component or luminous side walls which improve its appearance and light up adjacent ceiling areas.

Where the invention is embodied in four-lamp luminaires, it is contemplated that the luminaire 36 will be symmetrical with respect to a central medial plane and have two pairs of lamps on either side of the central plane and each pair of lamps is associated with downwardly acting reflectors one of which terminates at or close to 4® the plane Of the center of the upper lamp, while the other reflector extends higher but does not cross the vertical plane through the lamp centers and the bottoms of the latter reflectors meet at the center of the fixture. Such a construction ⁴⁸is similarly economical of material, has well controlled dominant output for direct lighting and the upwardly escaping light may be allowed to go upwardly for indirect lighting or directed toward translucent side panels. so

Other and further objects will hereinafter appear as the description proceeds.

The accompanying drawings show, for purposes of illustrating the present invention, several embodiments la which the invention may take fa™, 6® (CL 240—51.11) it being understood that the drawings are illustrative of the invention rather than limiting the same.

In these drawings:

Figures 1 and 2 are transverse sectional views through two-lamp luminaires, Figure 1 showing an exposed luminaires mounted at or below the ceiling level, and Figure 2 showing a luminaire partly recessed;

Figures 3 and 4 are transverse sectional views through four-lamp luminaires having luminous side walls;

Figure 4α is a perspective view of the luminaire of Figure 4;

lg Figure S is a fragmentary sectional view of a pendent four-lamp luminaire arranged for direct and indirect lighting;

Figure 5α is a perspective view of the luminaire of Figure 5; and

2® Figure 6 is a sectional view of a pendent twolamp luminaire arranged for direct and indirect lighting.

For clarity and simplicity of the drawings lamp and starter sockets, wiring, supports and the like 2® have been omitted, as’ well as many structural details which a complete luminaire would employ.

Figure 1 illustrates a luminaire adapted to be mounted in an exposed position either pendent or close to the ceiling. The top wall of the luminaire is illustrated at 10. This will generally be a metal wall painted white inside so as to provide a diffuse reflecting surface. The side walls of the luminaire are indicated at 11,11, and these are typically louvered or diffusing plastic sheet material or glass. The bottom wall 12 of the enclosure is preferably a louvered plastic sheet which permits direct transmission of light downwardly but limits the longitudinal spread. The framework of the enclosure includes S-shaped metal channels 10' at the top and channels at right angles to one another at the bottom corners as indicated at Π', (j'.

Two fluorescent lamps are indicated at Sa’and 16. They are mounted one directly above the other and almost in contact. The reflectors 8S IS, as shown in Figure 1, are alike and have their upper edges 16, t@ close to the upper lamp and at substantially the level of the center 13' of that lamp. The lower edges 17, i 7 of the reflectors are substantially one-half the lamp diameter below the lower lamp to provide a cut off angle which may vary, but is here indicated as being about 75° above the nadir, and hence the reflectors intercept light emitted laterally from the upper lamp below the plane through its center and from the lower lamp and allow a certain portion of

2,436,635 the light from each lamp to escape as direct light.

The upper portion 15α of the reflector 15 is designed to act on light from the lower lamp and reflect it downwardly at or near the vertical as indicated by the· ray 18—18’; the intermediate portion 15b to downwardly reflect light from the closely adjacent surfaces of the lamps (which are brightest due to reflection of light on each lamp) at steep angles as indicated by the ray 19—19'; and the lower portion 15c to act on light from the lower lamp and reflect it back across the medial plane A—A so as to spread the rays widely, as shown by the rays 20—20', 21—21'. The rays 22 from the upper lamp are reflected downwardly as indicated at 22' in more vertical angles than the widely spread rays 20', 2Γ. Thus the employment of two lamps one above the other with two reflectors indicated makes it possible to obtain a light distribution which incorporates the high angle light typical of extensive distribution and the vertical light typical of concentrating distributions. The portions 15α, 15b and 15c are typically a succession of parabolic arcs with focal points at and above the center 14' of the lower lamp with the axes tilting more and more from the vertical as will be obvious from the slope of the reflected rays. Typical axes are indicated by dot-and-dash lines i 8α, 19α and 2 0α. The curving contour could also be composed of a succession of circular or elliptical arcs.

The light which is emitted upwardly and to the left of the median plane A—A of the luminaire of Figure 1 escapes and is in part reflected downwardly by the diffuse cover 10 of the luminaire, as indicated at 23, where it strikes the outer surface of the reflector 15 for reflection towards the translucent wall II, as indicated at 24, or it may be reflected towards this translucent wall as indicated at 25. Also some of the rays escape from the lamp 13 directly to the translucent side wall, as indicated at 26.

In the luminaire in Figure 2 the direct light is controlled in the same manner as in Figure 1, but owing to the depth of the cover 10α of the luminaire and the shallowness of the side walls I la the only light which reaches these side walls is that reflected by the outside of the reflectors 15, as indicated by the rays 27.

The fixture shown in Figure 3 is symmetrical about a central median plane 30, 30. The luminaire has a top wall 31, translucent side walls 32, 32 and a translucent bottom wall 33. It carries two pairs of fluorescent lamps 34, 35 arranged one above the other in vertical planes 36—36. The portions of the luminaire beyond the planes 36—36 are optically the same as onehalf of the luminaire shown in Figure 1 and the same light control takes place, as indicated by similarly disposed light rays. Between the pairs of lamps the luminaire is provided with reflectors 37, 37 which extend from the central plane 30, 30, near the bottom closure, upwardly so as to come close to the outer surfaces of the upper lamps 34 at considerable distances above the plane through the centers 34' of these lamps. The reflectors extend up to and are secured to the cover or top 31, as indicated at 38, 38. The stepped contour Indicated is merely for convenience in manufacture.

The reflectors 37, 37 are composed of parabolic arcs similar to those employed in the smaller reflectors previously described. By selecting larger arcs it is possible to have the upper parabolic arc extend above the lamp center 34' rather than terminate at it, and hence more of the light from the upper lamp is intercepted and reflected down through the bottom of the enclosure. The paths of light rays are indicated by tne lines 39, 39', 40, 40', 41,41', 42, 42' and 43, 43'. So lar as tne control of the light emitted by the lamps below the plane through the center of the upper lamp is concerned, the two reflectors act suostantially alike. For the down lighting from eacn pair of lamps the optics are symmetrical even thougn the structure is asymmetrical. The luminaire is much narrower than it would be if all four of the reflectors were the size of the central reflectors.

If desired, the top of the luminaire of Figure 3 may be provided with openings such as illustrated at 44 at the right, these openings having light transmitting covers 45 or not as desired so that a smali indirect component may be obtained. The space between the reflectors 37, 37 may be employed to receive the ballast Indicated at 46.

The luminaire 47 shown in Figures 4 and 4α employs the same arrangement of lamps and reflectors as indicated in Figure 3, and the same reference characters are employed. Instead of having the lower outside corners of the luminaire made up by channels 11'—11' arranged at right angles to one another as shown in Figures 1 and 3, the bottom wall 48 is bent upwardly and is received in an S-shaped channel 49 which also supports the side panel II. Its side walls 11 will be brighter due to light reflected as indicated at 50.

The luminaire of Figure 5 employs the same pairs of lamps 34, 35 and reflectors 15' and 37 as in Figure 3. Instead, however, of having the top of the luminaire closed as in Figure 3, it is here left open so that light rays such as 51 from the upper lamp may escape upwardly without interference. Instead of having light transmitting side walls the luminaire is provided with reflecting side walls 52 which may be opaque or translucent and are adapted to deflect light rays such as 53 upwardly as indicated at 53'. The bottom 54 is arranged to receive some light rays such as 55 and reflect them upwardly on to the outer surface of the side walls 52 as indicated at 56, so that these walls appear luminous.

Figure 6 shows a luminaire 60 embodying the same arrangement of lamps 13 and 14 and reflectors 15, 15 as illustrated in Figures 1 and 2. It employs two reflectors 62, 62 similar to the reflectors 52 of Figure 5, and the bottom 63 of the luminaire 60 is similar to the outer portion of the bottom 54 of the luminaire of Figure 5 so that in the luminaire in Figure 6 part of the light escapes upwardly for indirect lighting and part of it is diverted so as to illuminate the outer surfaces of the deflectors 62.

The arrangements shown herein provide a well controlled dominant output of light for direct lighting by reason of the use of the reflectors which avoid trapping or blocking off light from the top of the upper lamp, and make it possible to use the light from this part of the upper lamp either for illuminating translucent side walls of the luminaire or for indirect lighting. It is possible to provide a four-lamp luminaire with reflectors for controlling the light output in an effective manner with desirable cut off angles and yet not have the luminaire excessively wide. For example, a luminaire such as illustrated in Figure 3 arranged for four 40 watt lamps may be about 13 wide.

Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the claims', I wish it to be under10

SO

8,430,083 s stood that the particular forms shown are but a few of these forms, and various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.