US2864939A - Shallow luminous fluorescent lighting fixture - Google Patents

Description

Dec. 16, 1958 M. BODIAN ET AL 2,864,939

SHALL IOW LUMINOUS FLUORESCENT LIGHTING FIXTURE Filed April 22, 1957 2 Sheets-Sheet 1 WKW Dec. 16, 1958 M. BODIAN ET AL SHALL-OW LUMINOUS FLUORESCENT LIGHTING FIXTURE 2 Sheets-Sheet 2 Filed April 22, 1957 mm Gn om mm ATTORNEY SHALLOW LUMINOUS FLUQRESCENI-LIGHTING.

Marcus Bodian, Los Angeles, and William B. Rosenfield,

Pacoima, Calif, assignoi-s to Sunbeam Lighting Company, Los Angeles, Calif.

ApplicationApril 22, 1957, Serial No, 654,3 67 Claims. (Cl. 240-5111) This invention relates to a luminous fluorescent lighting fixture.

One object of the invention is to provide a self-luminous enclosed ceiling type light fixture of whichfs'ubstan tially the only portion visible from the floor is an evenly" lighted translucent cover. Another object is to provide a four lamp ceiling type fluorescent light fixture with a translucent cover which is shallow and lies close to the reference being made to the accompanying drawings in which:

Fig. l is a perspective view of a fluorescent light fixture as mounted on a ceilingQfollowing'our invention;

Fig. 2 is a bottom plan view, with parts broken away to show portions of the interior structure; Fig. 3 is a fragmentary vertical cross-sectional view taken on the line 33 of Fig. 2;

Fig. 4 is a vertical cross-sectional view taken on the line 44 of Fig. 2, the essential elements intliis'drawing being proportionally scaled; i Fig. 5 is a fragmentary vertical cross-sectional view taken on the line 5-5 of Fig. 3;

Fig. 6 is a fragmentary plan view taken on the line I 6-6 of Fig. 5;

Fig. 7 is a perspective view of the intermediate V- shaped reflectors which are ata ched to the base plate of the fixture; and i Fig. 8 is a perspective view separately showing the ballast housing including its V-shaped bottom reflecting surfaces. l

Referring to the drawings which show a preferred form of our invention, the fixture consists of a top plate 11 which is generally flat and adapted to be mounted parallel to and adjacent the ceiling, being spaced from the ceiling by the ballast housing cover 12 which is attached to up-turned margins 13 defining a longitudinal opening 14 in the center of said top plate 11, this opening being.

adapted to receive the sides 15 of the ballast housing 16 (shown particularly in Fig. 8). Pushed-out tabs 17 are provided on the inner surface of the up-tur'ned margins 13 of the opening 14 in the cover, these tabs being spaced and arranged to engage the tab openings 18 on the sides 15 of the ballast housing 16 as shown. This arrangement permits the removal of the ballast housing 16 when it is desired to get access to the ballast elements 19.

The ballast housing 16 consists of the said side walls 15, which are connected by a pair of v-b'ottom 'plates 22 which are longitudinally joined at an external angle of about 226, the outer surfaces serving as reflecting surfaces for the light from the two inner fluorescent .larnps.

Air space for cooling of the ballast units 19 is provided on both sides, and underneath the units, in the space between the sloping reflector plates.

The top plate 11 which is generally made of sheet metal and is longer than it is wide is provided along the side margins with rectangular grooves 20, each of these grooves 20 having an up-turned edge 21 which, in the preferred form shown, is level with the upper plane of the top plate 11. Attached to the under side of the top plate 11 and depending therefrom adjacent the ends of said plate are socket end members 23 which are of sheet metal formed as structural beams to give strength and rigidity to the structure, these end members 23 being provided in their upright portions with holes 24 in which are mounted electrical connecting sockets 25 for the fluorescent lamps 26 which are used in this fixture, these lamps extending from one socket end plate to the other.

A difluser frame 30 extending around the margins of the top plate 11 is removably and hingedly mounted on said top plate 11, the diffuser frame holding a deeply dished translucent diffuser 31 which substantially completely encloses-the fixture except the top plate, and which in closed position is substantially the only portion of the fixturewhichis visible from the floor beneath. The diffuser frame 30 consists of structural end members 32 which are shaped to cover the socket end members 23, and which have inwardly directed flanges 33 on their lower margins. The frame 30 also comprises structural side members 34 extending between the ends of said end members 32, being removably held together by screw bolts 35. The side members 34 which are sheet metal strips are edge-bent at the upper edge to a downwardly directed hinging edge 36 which'rests inside the grooves 24) in the top plate 11. The side members 34 also have I inturned flanges 37 along their lower edge portions.

The diffuser 31 consists of a molded or otherwise formed light transmitting sheet material dished to cover and enclose the fluorescent tubes, reflectors, etc. mounted on the top plate 11, the diffuser having sloping walls 38 and outwardly turned edge flanges 39 extending from the upper edges of said walls, which flanges rest on the inturned flanges 37 of the side members 34 and also on the inwardly directed flanges 33 on the lower edges of the end members 32 of the diffuser frame 31 The dished diffuser 31 is thus framed and supported by the diffuser frame 30 so that when assembled, it serves as a unitary cover for the lighting fixture. When mounted in place, the hinging edges 36 of the diffuser frame rest in the grooves 20 on both sides of the top plate 11, the parts of the structure being proportioned so that the distance between the up-turned edges 21 of the top plate is slightly greater than the distance between the downwardly directed hinging edges 36 of the diffuser frame 30. When it is desired to gain access to the interior of the fixture, one hinging edge 36 of the frame 30 on one side only of the fixture is raised up and moved laterally until it clears the up-turned edge 21 of the groove 20, thus removing all support from one side of the diffuser frame 30 with the diffuser plate securely mounted therein. The upturned edge 21 on the opposite side then cooperates with the hinging edge 36, also on the opposite side of the fixture, so that the frame 30 and the mounted diffuser 31 are hingedly supported in a hanging downward position shown in broken lines in Fig. 4, giving full access to the interior of the fixture. The diffuser frame 30 and the diffuser 31 are again restored .to the closed position by raisingthe free hinging edge 36 over the corresponding up-turned edge 21 of the groove-20 and allowing the hinging edge tothen restinside the groove. The displacement of the top plate 11 from the ceiling by the protrudingballast housing 16 permits full opening of the diffuser frame 30 The difiuser 31 is generally flat on its under surface portion 40 between the sloping walls 38 which have been described, except that preferably an inverted V-shaped boss or groove 41 is provided in the longitudinal direction Patented Dec. 16, 19 58 in the center of the flat portion 40, this V-shaped groove on its inside surfaces being disposed to receive incident light from the adjacent fluorescent lamps 26, as well as some reflected light from the Vreflector bottom of the ballast housing as will be described. The central inverted V-shaped groove 41 in the ditfuser 31 also serves to strengthen the diffuser 31, the diffuser 31 being preferably made from a molded plastic material, a polyacrylic resin such as Plexiglas. The diffuser 31 is made translucent either by the incorporation of opaqueing powders in the plastic composition or preferably by minute etching of one or both surfaces of the Plexiglas, or by other suitable means. The depth of the dished diifuser is preferably no greater than twice the diameter of the tubular fluorescent lamp 26.

Attached to the under side of the top plate 11 and disposed intermediate the pairs of fluorescent lamps 26 on either side of the ballast housing are V-shaped reflectors which are arranged at angles tangential to the surfaces of the lamps in order to reflect the light from the upper portions of the fluorescent lamps evenly over the inner face of the diffuser. The V-shaped reflectors 43 are preferably sheet metal, coated or surfaced with a reflecting material such as Alzac, and are attached to the top plate 11 by tabs 44.

he drawing, Fig. 4, shows, to proportional scale, the principal dimensions which are necessary to attain the shallow, fully enclosed fixture for four lamps, whose translucent cover or diffuser attains a substantially uniform brightness over its entire area. The actual dimensions in cross-section are related to and based upon the diameter of the fluorescent lamps. One much used standard lamp has an outside diameter of 1 /2 inches. Using a as a selected unit of length (for example A; inch), a lamp diameter A is 12a; the distances between lamps centers, B and B, are 42 to 4811, and these centers are aligned parallel to the top plate 11; the minimum distance C of the diffuser 31 from the lamp surfaces is 8a; the total visible width of the diffuser is 93a; the V-shaped reflectors 43 have two reflecting faces 45, 45 which are 16a in width, and these faces are disposed at an external angle E of about 226 to each other, intermediate the outer pairs of lamps; this angle making the reflecting surfaces parallel to the tangent to lamp surfaces; the bottom of the ballast housing has two reflecting surfaces 22, 22, which are 18a in width, disposed in edge contact longitudinally at an exterior (to the housing) angle of about 226 to each other. The distance D from the base plate 11 to the flat portion of the diifuser is 29a. The length of the fixture is determined by the length of the available lamps; one standard length being 48 inches.

When constructed in the essential proportions given above, using 40Tl2/RS2500 Lu./4.l c./in. lamps (4), the diffuser, at the indicated angles, had brightness values as follows:

The available light was directed 96 percent downwardly, and the over-all efficiency was 66 percent.

The advantages of our invention will be apparent from the above description. By using reflectors to direct the light from the four lamps on to the diffuser (which is also the enclosing cover for the fixture), a uniformly lighted luminaire is provided which is less in thickness than twice the diameter of the tubular lamps. The light is diffused to uniform brightness which does not irritate the eyes. The fixture, even though spaced a little distance from the ceiling, to provide cooling air, still presents the shallow appearance simulating a recessed ceiling fixture. The unit fixtures as above described may be placed in multiples, preferably in end-to-end relation, to give uniform room lighting.

We claim:

1. A ceiling fluorescent light fixture comprising an elongated rectangular ballast housing having a depending V-shaped bottom member with outer reflecting surfaces, the top of said housing being adapted for mounting against the ceiling; an elongated plane top plate for said fixture, said top plate having a central elongated opening through which said ballast housing extends and to which said top plate is attached for holding said top plate parallel to but spaced from the ceiling; a dished translucent diffuser having a substantially plane face forming an enclosing housing for tubular fluorescent lamps, the end and side margins of said diffuser tapering upwardly toward the margins of said top plate; means at the side margins of said diffuser for removably attaching said diffuser to the margins of said top plate; means for oper- 'atively mounting pairs of elongated fluorescent lamps in spaced-apart relation with the upper surfaces of said tubes closely adjacent the under surface of said top plate, said pairs being disposed on both sides parallel to the reflecting surfaces of said ballast housing bottom; and elongated V-shaped reflector attached to the underside of said top plate and disposed intermediate the two lamps of each pair.

2. The ceiling fluorescent light fixture defined in claim 1, in which the means for mounting the diffuser to the margins of said top plate consists of a turned-in-and-down strip on the side margins of said dilfuser engaging a marginal trough on the side edges of said top plate.

3. The ceiling fluorescent light fixture defined in claim 1, in which the diffuser is provided with a centrally disposed longitudinally inverted V-shaped rib whose apex is adjacent the apex of said V-shaped bottom member of said ballast housing, whereby the sides of said diffuserrib receive direct light from said fluorescent lamps whereby to make said rib shadow free and of substantially equal brightness to the plane surface of said diffuser.

4. The structure defined in claim 1 in which the plain area of the diffuser is separated from the top plate by a distance not greater than twice the diameter of the tubular fluorescent lamps.

5. In a fluorescent light fixture having a plane base plate adapted to be mounted adjacent but spaced from a ceiling, and having a plurality of fluorescent tubular lamps mounted in spaced-apart parallel relation on said base plate, and close to the surface thereof, and also having a dished translucent diffuser underlaying and removably attached to said top plate to form a housing for said elongated fluorescent lamps; means for reflectively distributing the light from said fluorescent lamps evenly over the entire area of said dilfuser comprising angularlydisposed plane reflecting surfaces attached to said base plate disposed intermediate and in light reflecting position adjacent pairs of lamps, said reflecting surfaces extending downwardly at least to the elevation of the axes of said lamp.

References Cited in the file of this patent UNITED STATES PATENTS

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