US3733482A

US3733482A - Fluorescent luminaire with vertically oriented u-shaped lamp

Info

Publication number: US3733482A
Application number: US00165256A
Authority: US
Inventors: J Miller; E Monte
Original assignee: Sunbeam Lighting Co
Current assignee: Sunbeam Lighting Co
Priority date: 1971-07-22
Filing date: 1971-07-22
Publication date: 1973-05-15
Anticipated expiration: 1990-05-15

Abstract

Disclosed is a novel luminaire structure employing a U-shaped fluorescent lamp mounted in a rectangular or cylindrical light diffuser in either an upstanding or depending position. The diffuser constitutes the radiating surface of the luminaire. The diffuser and lamp or lamps are supported from a base member which contains the electrical connections of the luminaire. The electrical ballast associated with the lamp or lamps is secured to the base in an elongated upstanding housing parallel to the leg portions of the lamp or lamps and positioned therebetween. The ballast housing has a reflective surface whereby the light output of the lamp structure is enhanced and has a portion of its metal surfaces in contact with the ballast whereby heat is conducted away from the ballast and is dissipated by radiation from the housing. Also disclosed is a combination of a vertically oriented Ushaped lamp plus enclosing diffusers of particular orientation which minimizes glare by limiting light distribution at the angle of 25* with respect to the nadir.

Description

ite States Patent 11 1 Miller et al.

May 15, 1973 154] FLUORESCENT LUMINAIRE WITH VERTICALLY ORIENTED U-SHAPED LAMP [75] Inventors: Jack V. Miller, Sierra Madre; Ernest Monte, Pasadena, both of Calif.

[73] Assignee: Sunbeam Lighting Co., Los Angeles,

Calif.

[22] Filed: July 22, 1971 [21] Appl. No.: 165,256

[52] US. Cl. ..240/51.12, 240/78 LD, 240/81 LD,

[51] Int. Cl. ..F2ls 3/00 [58] Field of Search ..240/51.12, 78 R,

240/78 CF, 78 LD, 81 R, 81 LD, 106 R, 106.], 25, 9.5

[56] References Cited UNITED STATES PATENTS 2,793,285 5/1957 Brainerd ..240/51.l2 X

2,063,744 12/1936 Kramer ..240/78 LD 3,207,893 9/1965 Nado ..240/25 3,062,953 11/1962 Clark et al. ..240/l06 R X 3,069,974 12/1962 Marks et a1.... ..240/9.5

2,814,721 11/1957 Fry ..240/5l.l2

3,371,201 2/1968 Yonkers ..240/106 R X 3,197,629 7/1965 Williams et al.... ..240/25 3,466,437 9/1969 Ruehl ..240/l06 R FOREIGN PATENTS OR APPLICATIONS 215,086 5/1924 Great Britain ..240/106.l

lillllllllllllllllllll OTHER PUBLICATIONS Fluorescent Lantern Unit Advertisement, Electrical Review, page 58, published Sept. 2, 1949 Primary ExaminerJoseph F. Peters, Jr. Attorney-John E. Wagner [5 7] ABSTRACT Disclosed is a novel luminaire structure employing a U-shaped fluorescent lamp mounted in a rectangular or cylindrical light diffuser in either an upstanding or depending position. The diffuser constitutes the radiating surface of the luminaire. The diffuser and lamp or lamps are supported from a base member which contains the electrical connections of the luminaire. The electrical ballast associated with the lamp or lamps is secured to the base in an elongated upstanding housing parallel to the leg portions of the lamp or lamps and positioned therebetween. The ballast housing has a reflective surface whereby the light output of the lamp structure is enhanced and has a portion of its metal surfaces in contact with the ballast whereby heat is conducted away from the ballast and is dissipated by radiation from the housing.

Also disclosed is a combination of a vertically oriented U-shaped lamp plus enclosing diffusers of particular orientation which minimizes glare by limiting light distribution at the angle of 25 with respect to the nadir.

17 Claims, 11 Drawing Figures PATEHTEU 3,733,482

SHEET 3 OF 3 O l /FROM NORMAL I l o FROM NADIR FLUORESCENT LUMINAIRE WITH VERTICALLY ORIENTED U-SHAPED LANIP BACKGROUND OF THE INVENTION The most common fluorescent luminaire in use is constructed in the form of a generally flat box mounted upon or recessed into a ceiling. Five sides of the box are normally made of sheet metal, with the bottom surface facing into the room being a lens of transparent, lighttransmitting material. Both straight lamps and U- shaped lamps are used in identical fashion within the luminaire, so that in each case only a minority of the light radiated from the lamps falls directly on the lens and the majority of the radiated light impinges on the inner surfaces of the sheet metal box. The trapping of light and the reflective losses of the metal surfaces usually result in the loss of approximately one third of the total lamp output.

One partial solution the trapped light losses has been the use of wrap-around luminaires. These fixtures have transparent sides to allow more of the lamp output to escape from the lamp compartment. However, the need to maintain structural stability in the metal box or can as well as support the wrap-around lens has always resulted in about half of the viewable solid angle of the lamps being exposed to the can, and the other half being exposed to the lens. Again, substantial losses in efficiency occur in inner reflections within the can.

A continuing problem faced by the designer of fluorescent luminaires is the heat generated by the lamp ballast. The ballast will quickly overheat if it is not mounted in contact with a thermal conductor that will carry the ballast heat away and dissiptate it. A typical ballast will have only 50 percent of its rated life if al lowed to operate at C. over the design temperature, and will operate the lamp less efficiently during that shortened life span. In a typical fluorescent luminaire comprising a flat box-shaped can that is mounted to a ceiling surface, the ballast fastened to the upper metal surface of the fixture cam, adjacent to the ceiling surface. The ceiling, usually of mineral-base materials, is an excellent thermal insulator and substantially blocks heat transfer from the top of the fixture. Aluminum radiator plates are often attached to a second surface of the ballast to conduct away heat and radiate into the lamp compartment, with associated penalties.

A problem exists which is peculiar to the design of luminaires using fluorescent U-shaped lamps. This problem is related to the very non-uniform light output from the lamps. The U-shaped lamp is relatively dim near the lamp bases, emitting very little usable light in the first few inches of tube. Conversely, the bent portion of the U" is much brighter than the areas nearer the bases. Also it has been found that the inner portions of the length of the legs is considerably brighter than the outer portions of the legs. This is because the light radiated from one leg illuminates the opposite leg and is re-reflected from the opposite leg. As a result of these effects conventional flat-pan luminaires usually show rather marked lamp images in their light diffusers, and are usually visibly brighter at the end of the fixture containing the bent portions of the U-shaped lamps.

Another problem in luminaire design is related to the unit brightness of the lens of light diffuser. Economics will dictate that the lighting fixture be as small as possible. On the other hand, visual comfort of people viewing the luminaire requires that the lens brightness be limited. This compromise is important on typical flatpan type of U-shaped lamp luminaire, which usually uses two 40-watt U-shaped lamps in a 2-foot square fixture. If all of the lower surface of the luminaire were lens, then there would be nominal lamp watts illuminating 4-square feet of lens, giving a power density of 20 watts per square foot. As a result, these compact fixtures usually require very exacting lens control to maintain a good level of comfort for the viewer, and even then are often too bright.

Not only is brightness a significant problem, but prior art luminaires also almost universally produce a light distribution pattern with high intensity in the glare producing angle of 25 with respect to the nadir.

BRIEF STATEMENT OF THE INVENTION We have designed a fluorescent lighting luminaire which utilizes the desirable shorter length single end mounting characteristics of the Ushaped fluorescent lamp and additionally overcomes its limitations. The

structure Of Our IHVCIIIIOII mounts one 01' more U- shaped fluorescent lamps from low base or support structures. The required ballast for the lamp or lamps is in the form of an elongated rectangle or cylinder secured at one end to the base and upstanding between the legs of the lamps. The exterior of the ballast is reflectively coated whereby it serves to redirect output light radiated inwardly by the lamp legs and overcome the characteristic dark line normally produced in U- shaped lamp fixtures caused by the asymmetrical shape of the light emitting areasand the light absorption encountered by one lamp or leg directly exposed to another lamp.

The lamp or lamps are enclosed in a light transmitting housing which may be either transparent or translucent and in either case, the lamp presents a substantially uniform radiation pattern in the transverse plane and an attractive appearance.

Another characteristic of the U-shaped lamp is also utilized in this invention. In such lamps, the U-bend tends to be slightly brighter than the leg portions. Therefore, using an end of the housing having a different light transmissivity from the side walls can produce virtually any desired light distribution pattern. For example, for a suspended ceiling light with translucent side walls and egg crate end wall, approximately 40 percent of the light from the luminaire is radiated in an upward hemisphere toward the ceiling to give a lighted ceiling appearance and approximately 60 percent in the downward hemisphere with a dominant beam in a downward cone subtending an angle of 45 about nadir BRIEF DESCRIPTION OF THE DRAWINGS These and other features of this invention may be more clearly understood from the following detailed description in which:

FIG. 1 is a perspective view of a pendant mounted ceiling fixture employing this invention;

FIG. 2 is a perspective view of a table luminaire employing this invention;

FIG. 3 is a vertical section through the fixture of FIG. 1 with a portion broken away for clarity;

FIG. 4 is a horizontal section through the fixture of FIG. 2;

FIG. 5 is a light distribution pattern of the fixture of FIG. 1 in a horizontal plane;

FIG. 6 is a light distribution pattern of the fixture of FIG. 2 in a horizontal plane;

FIG. 7 is a light distribution pattern of a three lamp fixture in a horizontal plane;

FIG. 8 is a vertical section through another embodiment of the invention;

FIG. 8a is a perspective view of a portion of the vertical wall of one embodiment of the diffuser of FIG. 8;

FIG. 8b is a perspective view of a portion of the vertical wall of another embodiment of FIG. 8;

FIG. 9 is a vertical section through an embodiment of this invention with light transmission through both the side walls of the housing employing a polarizing diffuser.

DETAILED DESCRIPTION OF THE INVENTION Now referring to FIG. 1 showing a ceiling suspended rectangular lighting fixure 10 including a mounting plate 11, a suspension rod or tube 12 secured to the base or body portion 13 of the fixture. In this embodiment, the base portion 13 is a shallow square pan, preferably of metal and mounting within its confines the interconnecting wiring as well as the socket for one or more U-shaped fluorescent lamps as better seen in FIG. 3. Secure and depending below the base 13 is a diffuser housing 14 in the form of a rectangular body of, for example, sheet, molded or extruded acrylic, plastic, glass, or other light transmitting material. The lower end of diffuser 14 is partially closed by an egg crate type diffuser panel 15. Preferably, the light transmission characteristic of the planar wall portions 16 of the diffuser housing 14 are different from the bottom panel 15. By appropriate selection of materials for the wall portions 16 of diffuser housing 14 and the end panel 15, the light distribution from the fixture can be controlled.

From the exterior of the fixture of FIG. 1, the appearance is similar to prior art incandescent fixtures with the exception that no visible hot spot or hot spots can be seen. Instead, the fixture presents appearance of a uniformly illuminated square column. The height or thickness of base member 13 is determined principally by aesthetic considerations since the electric components which it contains are of small size at is described below. In the proportion shown in the drawings, the base is of sufficient size to provide an appearance of massiveness or strength to the fixture, yet not overpowering.

An alternate embodiment of the same principle appears in FIG. 2 as an upstanding table lamp 20 shown on a coffee table 31 as would be found in a typical living room. In this case, the table lamp includes base 22, body diffuser 23 and cap portion 24. The base portion 22 is similar to the base 13 of the embodiment of FIG. 1 and contains the wiring of the fluorescent table lamp. The light transmission characteristic between the side walls and the cap 24 again are different in this case with the cap 24 being opaque to avoid brilliant light directed towards the occupants of the room. Again, the side walls 25 of the body member 23 may be diffusing surfaces of acrylic, glass or similar material. Given this invention as described below, the table lamp 20 of FIG. 2 presents a relatively uniform white rectangilar emitting surface with light emission in all degrees of azimuth being substantially uniform.

The uniform lighting characteristic of the embodiments of FIGS. 1 and 2 may be more clearly under stood by referring to FIGS. 3 and 4, FIG. 3 being a vertical section through the base 13, difiuser 14 of fixture 10 of FIG. 1. Fig. 3 shows a pair of

U-shaped lamps

30 and 31 secured by

sockets

32 and 33 in an inverted or suspended position in parallel side-by-side relation. Positioned in similar relationship between the two

lamps

30 and 31 is a housing 35 of generally rectangular shape and enclosing the ballast 34 of the circuit for the lamps. This ballast 34 is interconnected with the lamps in a manner which is well known in the fluorescent lamp art. The system is interconnected by cable which passes through the tube 12 to the line.

Shown in FIG. 3 are housing 35 and its ballast 34 which are of substantial length, and in fact, extend the entire length of the two

lamps

30 and 31. The exterior surface of the housing 35 is painted white or other highly reflective color. Mounted vertically in the region between the legs of the U-shaped lamps this ballast 34 and housing 35 provide secondary radiating surface in the areas where the lamps provide no radiant energy. Therefore, if viewed from any azimuth angle, the fixture presents a relatively uniform brilliance.

Radiation in the downward direction, to wit, from nadir is different from that of the side walls 16 of the fixture. This difference is the result of the egg crate diffuser l5 and the fact that the lamps have a higher brilliance to the regions of the U-bend. Therefore, by selection of the end diffuser, the entire assembly may be given increased illumination in the axial direction with respect to the lamps or as in contrast in FIG. 2, reduced illumination in that direction. The use of openings 36 or slits 37 at the upper end of the diffuser 16 or base 13 allows cooling of the

lamps

30 and 31 as well as ballast 34 by convective currents through the interior of the diffuser. Far more efficient cooling and operation is therefore possible employing this invention as compared with ballasts enclosed with lamp boxes.

The relative position of a single U-shaped lamp and ballast is clearly illustrated in the horizontal sectional view shown in FIG. 4. In this case, a single lamp 40 within a rectangular diffuser 25 is positioned with the legs upstanding generally along a diagonal to the enclosure. The

lamp legs

40A and 40B, of course, are connected with a U-section and unshown in sectional view FIG. 4. Positioned between the

upstanding legs

40A and 40B is a parallel upstanding housing 41 containing internal ballast transformer 42. The housing 41 is positioned substantially midway between the two legs of the lamp and the exterior surface of 41 again reflectively coated to enhace and improve the uniformity of radiation in all degrees of azimuth. The housing 41 provides additional significant functions as well to improve the performance of the lamp. For one, it acts as an RF shield for the ballast transformer to minimize radio interference. In certain cases, U-shaped lamps have proved difficult to start and easily extinguished in the absence of some conductive body extending generally along this length. This housing 41 serves that additional purpose as well.

The effect of the designs of FIGS. 1-4 are illustrated in radiance diagrams of FIGS. 5-7. As shown in FIG. 5, the light distribution of the embodiment of FIGS. 1 and 3 in horizontal plane is relatively uniform. It is apparent that the walls of the housing 35 are positioned directly in the area between the

lamps

30 and 31 thereby providing shielding and diffusion of the highbrightness inward-facing surfaces of the legs of the U- lamps. The lamp legs and the reflective housing 35 extending nearly the entire length of the lamp housing therefore provides almost an identical pattern to that shown in FIG. 5 in any horizontal plane.

The light distribution in the horizontal plane is almost circular as represented by curve A. This circular distribution is measured without a diffuser and the presence of the diffuser will even improve the characteristic.

Superimposed upon the same diagram in FIG. 5 is curve B which represents the light distribution in the horizontal plane of the same U-shaped lamp in the absence of the central reflecting surface of housing 35. Curve B shows predominant lobes at angles approximately 60 from the axis C through the lamp. These lobes are believed to be the result of the summation of output from the two legs L and R of the U-shaped lamp. Along the axes C and D there is a definite valley in the output curve which is believed to be the result of either absorption or interference of the light from the two legs. In the case of axis D, the leg R tends to block any emission from the leg L and vice versa. The foregoing characteristic of the U-shaped lamp has given rise to the undesirable dark line of fixtures employing this lamp prior to this invention.

The light distribution in the vertical plane of the luminaire in accordance with this invention is illustrated in FIGS. 6 and 7 which denote two different embodiments.

In the embodiment of FIG. 6 the luminaire is mounted from a ceiling E in both the side walls 16 and bottom wall 15 which are light emitting. The light distribution characteristic shown in FIG. 6 is ideal from room lighting since it particularly avoids an excessive brightness in the downward direction at an angle 25 from the nadir. The luminaire also exhibits a low brightness per unit area since the lighting emitting area per watt of power consumed is approximately onequarter that of a conventional recessed luminaire.

If the luminaire in FIG. 6 is suspended and ceiling E is not present, the light distribution above the top of the luminaire is represented by the dashed lines.

As noted above, the luminaire in accordance with this invention can readily control the light distribution by selective light transmission qualities of the side wall 16 and bottom 15.

When the bottom 15 is opaque, as illustrated in FIG. 7, a toroidal distribution pattern is established with the areas of highest light distribution displaced outward from under the luminaire. In this embodiment the brightness per unit area is significantly greater and the light distribution pattern is particularly suited for general room illumination. Again, in FIG. 7, similar to FIG. 6, the distribution pattern when the lamp is suspended the absence of ceiling E is illustrated by dashed lines.

We have found that through the use of this invention of a vertical oriented fluorescent lamp and particular diffusers with light control in the vertical direction can be achieved and particularly avoid the undesired high brightness to area ratio of prior art luminaires and, at the same time, eliminate the undesired predominant radiation at an angle 25 with respect to the nadir which gives rise to objectionable glare.

The foregoing is achieved in accordance with the embodiment of this invention shown in FIG. 8 which illustrates a luminaire 50 suspended for example by tube 51 and having the mounting and support member 52. Contained within the member 52 is at least one U-shaped lamp 53 oriented vertically and enclosed within a beam-splitting diffuser of the types illustrated in FIGS. 8A and 8B. The beam-splitting diffuser, by its geometry, enhances radiation into two directions shown in the drawing and identified by the letters A and B. These directions, A and B, approximate 45. The beam A tends to illuminate the ceiling and the beams B tend to illuminate the room. The beam-splitting diffuser has reduced radiation parallel to the ceiling and at the unwanted 25 from nadir. The overall height of the fixture is determined by the lamp length and is approximately 24 inches, a dimension which is compatible with mounting suspended from a ceiling secured to the surface of a ceiling or in coffers. The same embodiment, as is apparent from FIG. 2, is also usable in the same vertical direction with the support member 52 being actually a base for mounting the inverted condition.

The diffuser of FIG. 8 may be of a number of types. We have found that a prismatic duffuser having nonparallel inside and outside surfaces is capable of producing a desired light distribution. Such a diffuser is shown in FIG. 8a. It comprises a cylindrical or rectangular tube of acrylic, glass or similar material having a symmetrical tube pattern 61 on its outer surface with teeth having a nominal angle from the normal of 37. The inner surface of the diffuser is a trapezoidal design with the side slopes 62 having an angle greater than that of the external tooth design. In all cases, the inner and outer surfaces are non-parallel and as illustrated in FIG. 8A the design results in both light diffusion and diversion of radiation from the plane normal to the surface into upward and downward conical beams. The beam-splitting diffuser is ideal for minimizing both horizontal and direct glare and the undesirable radiation within 25 from nadir which tends to produce reflected glare from horizontal surfaces such as table and desk tops.

Another embodiment of the diffuser which, in combination with the vertically oriented fluorescent lamp, is illustrated in FIG. 8B. It comprises an acrylic or glass tube 65 similarly having a trapezoidal configuration on its inner wall similar to FIG. 8A and lens ribs 66 on the outer wall. The tops 67 of the trapezoids are made opaque so that the only light emitted from the diffuser of FIGS. 8B is through the angular side walls 68 of each trapezoid and the lens. In this embodiment, similar to the lens of FIG. 8A, radiation is enhanced in the direction of the lens a and b of FIG. 8; and horizontal radiation as well as radiation within 25 from nadir is minimized. In both embodiments, the striations of FIG. 8A and the convex lens of FIG. 8B extend along the exterior of the fixture in a horizontal direction providing ornamental surface treatment to the diffuser as well as the very important function of beam control.

We have found that another combination of lamp and diffuser is particularly desirable in eliminating the reflected glare from a horizontal surface below a ceiling mounted luminaire. This embodiment is illustrated in FIG. 9 as including the vertically oriented lamp 63, with the diffuser 64 which, in this case, is of polarizing material oriented around the body of the diffuser. The peak polarization efficiency occurs at about the Brewster angle of the material at an angle of 65 measured from the horizontal plane normal to the diffuser. This peak of polarization for the vertically disposed diffusers of the invention then occurs at almost precisely an angle of 25 from nadir and greatly reduces reflected glare from light in that offending zone.

In each of the foregoing embodiments, the U-shaped fluorescent lamp is combined with a housing and diffuser to eliminate its inherent deficiencies and to provide a new fluorescent light superior to the prior art. Its use is now possible in a vertical direction particularly as a ceiling lamp and to provide fluorescent luminairs of design compatible with architectural requirements of low brightness per unit area, uniform brightness in a horizontal plane, and controllable brightness in a vertical direction.

The above-described embodiments of this invention are merely descriptive of its principles and are not to be considered limiting. The scope of this invention instead shall be determined from the scope of the following claims including their equivalents.

What is claimed is:

l. A fluorescent lighting fixture designed for positioning in a generally vertical direction comprising:

a supporting base member in the form of a closed box having length and width greater than its depth;

an elongated light-emitting housing secured to one face of said base member and extending in a direction generally vertical from the base member; said light emitting housing providing for relatively uniform light emission in a 360 horizontal pattern; socket means secured to the base member adjacent to said housing; at least one U-shaped fluorescent lamp engaging said socket means and positioned in said housing;

ballast means secured to said base and extending into said housing in longitudinal direction and symmetrically placed with respect to said U-shaped fluorescent lamp;

said ballast means having an exterior surface of light reflective finish whereby the U-shaped fluorescent 1 lamp constitutes a primary source of illumination and the reflective surface of the exterior of said ballast means constitutes a secondary source of illumination and said fixture provides relatively uniform light distribution in a horizontal plane.

2. The combination in accordance with claim 1 wherein said fixture mounts a single U-shaped fluorescent lamp and said ballast means is secured to said base member between the legs of the U-shaped lamp.

3. The combination in accordance with claim 1 wherein said fixture includes a pair of spaced U-shaped fluorescent lamps positioned in generally parallel relationship and said ballast means is positioned generally equispaced between the planes of said U-shaped lamps.

4. The combination in accordance with claim 1 wherein said fixture is designed to rest on a supporting table or structure with said housing extending above said base wherein said base constitutes the support for the lamp assembly.

5. The combination in accordance with claim 1 wherein said housing includes side walls having relatively uniform light transmitting properties in a hori zontal plane and the light transmittivity of said side walls is different from that of said end wall.

6. The combination in accordance with claim 5 wherein said end wall has a greater light transmission characteristic than said side walls and said fixture produces radiation in a horizontal direction of relatively uniform intensity the end wall of said fixture being in proximity to the U end of said U-shaped fluorescent lamp thereby producing a cone of greater intensity illumination in the generally vertical direction from said fixture with the angle subtended by said cone related to the horizontal dimensions of said end wall and its distance from the end of said U-shaped fluorescent lamp.

7. The combination in accordance with claim 5 wherein said end wall is opaque and said fixture produces radiation only in the generally transverse plane of substantially uniform intensity.

8. A fluorescent lighting fixture designed for positioning in a generally vertical direction comprising:

a supporting base member having one face adapted to constitute support for the entire lighting fixture and an opposite face upon which the lamp element is mounted;

an elongated light emitting housing secured to said opposite face and extending in a generally vertical direction from base member;

socket means secured to said supporting base member within said housing;

at least one U-shaped fluorescent lamp engaging said socket means and positioned in a generally vertical orientation within said housing;

elongated ballast means secured to said base and extending into said housing symmetrically placed with respect to the legs of said U-shaped fluorescent lamp;

said fixture including air handling openings in the regions of the U of said U-shaped lamp and said sockets whereby a convection air path is established through said fixture in a generally vertical direction through said housing and past said lamp and ballast.

9. The combination in accordance with claim 8 wherein one of said air handling openings comprise the openings in an egg crate diffuser in the end of said housing.

10. The combination in accordance with claim 8 wherein one of said air handling openings comprises slits through said base.

11. A fluorescent lamp assembly designed for mount ing in a vertical direction comprising a mounting base;

a pair of socket members for each fluorescent lamp mounted on said base in a manner to allow the mounting of a U-shaped fluorescent lamp in a vertical direction;

a ballast secured to said base and positioned between the legs of said U-shaped fluorescent lamp and extending in a generally vertical direction;

a diffuser secured to said base elongated in a generally vertical direction in a mounted position;

said diffuser providing relatively uniform light emission in a 360 horizontal pattern;

said diffuser including an end wall enclosing the diffuser to control the intensity of light from the U- portion of the U-shaped lamp in said fixture;

the side walls of said diffuser having a preferred direction of light transmission normal to the surface thereof and reduced transmission at an angle of 25 from the nadir.

12. The combination in accordance with claim 11 wherein said diffuser comprises a body of light transmitting material having an outer saw tooth pattern extending in a horizontal direction when mounted on the assembly having a lower level direction of radiation 25 with respect to the nadir direction.

13. The combination in accordance with claim 11 wherein said diffuser includes a body of light polarizing material oriented with the Brewster angle thereof at an angle of approximately 65 from the horizontal when the lamp assembly is in the mounted position whereby the intensity of light from said fixture in the direction of 25 from the nadir is less than the intensity of light entered in the horizontal plane.

14. The combination in accordance with claim 11 wherein said diffuser comprises a body of light transmitting material having an outer surface comprising an array of horizontally extending lens surfaces and said inner wall includes means reducing transmission in a horizontal direction for enhancing the radiation from said diffuser in directions approximately 45 above and below the horizontal.

15. The combination in accordance with claim 14 wherein said inner surface constitutes a horizontal extending array of truncated pyramids aligned with each lens.

16. The combination in accordance with claim 15 wherein said horizontally extending pyramids have opaque inner walls extending parallel to the surface of the diifuser whereby light from lamps enters the diffuser through said walls of the pyramid structure and exits through the lens structure.

17. A fluorescent fixture assembly comprising a base;

socket means secured to one side of said base for holding a U-shaped fluorescent lamp in a generally vertical direction;

elongated ballast means mounted between said sockets to extend between the legs of said U-shaped fluorescent lamp and substantially obscuring the view of one leg of a U-shaped fluorescent lamp by the other;

said ballast having a light reflective outer surface whereby the cooperation of said ballast in said U- shaped lamp produces a generally uniform light distribution in a horizontal plane.

Claims

1. A fluorescent lighting fixture designed for positioning in a generally vertical direction comprising: a supporting base member in the form of a closed box having length and width greater than its depth; an elongated light-emitting housing secured to one face of said base member and extending in a direction generally vertical from the base member; said light emitting housing providing for relatively uniform light emission in a 360* horizontal pattern; socket means secured to the base member adjacent to said housing; at least one U-shaped fluorescent lamp engaging said socket means and positioned in said housing; ballast means secured to said base and extending into said housing in longitudinal direction and symmetrically placed with respect to said U-shaped fluorescent lamp; said ballast means having an exterior surface of light reflective finish whereby the U-shaped fluorescent lamp constitutes a primary source of illumination and the reflective surface of the exterior of said ballast means constitutes a secondary source of illumination and said fixture provides relatively uniform light distribution in a horizontal plane.

5. The combination in accordance with claim 1 wherein said housing includes side walls having relatively uniform light transmitting properties in a horizontal plane and the light transmittivity of said side walls is different from that of said end wall.

8. A fluorescent lighting fixture designed for positioning in a generally vertical direction comprising: a supporting base member having one face adapted to constitute support for the entire lighting fixture and an opposite face upon which the lamp element is mounted; an elongated light emitting housing secured to said opposite face and extending in a generally vertical direction from base member; socket means secured to said supporting base member within said housing; at least one U-shaped fluorescent lamp engaging said socket means and positioned in a generally vertical orientation within said housing; elongated ballast means secured to said base and extending into said housing symmetrically placed with respect to the legs of said U-shaped fluorescent lamp; said fixture including air handling openings in the regions of the U of said U-shaped lamp and said sockets whereby a convection air path is established through said fixtuRe in a generally vertical direction through said housing and past said lamp and ballast.

11. A fluorescent lamp assembly designed for mounting in a vertical direction comprising a mounting base; a pair of socket members for each fluorescent lamp mounted on said base in a manner to allow the mounting of a U-shaped fluorescent lamp in a vertical direction; a ballast secured to said base and positioned between the legs of said U-shaped fluorescent lamp and extending in a generally vertical direction; a diffuser secured to said base elongated in a generally vertical direction in a mounted position; said diffuser providing relatively uniform light emission in a 360* horizontal pattern; said diffuser including an end wall enclosing the diffuser to control the intensity of light from the U-portion of the U-shaped lamp in said fixture; the side walls of said diffuser having a preferred direction of light transmission normal to the surface thereof and reduced transmission at an angle of 25* from the nadir.

12. The combination in accordance with claim 11 wherein said diffuser comprises a body of light transmitting material having an outer saw tooth pattern extending in a horizontal direction when mounted on the assembly having a lower level direction of radiation 25* with respect to the nadir direction.

13. The combination in accordance with claim 11 wherein said diffuser includes a body of light polarizing material oriented with the Brewster angle thereof at an angle of approximately 65* from the horizontal when the lamp assembly is in the mounted position whereby the intensity of light from said fixture in the direction of 25* from the nadir is less than the intensity of light entered in the horizontal plane.

14. The combination in accordance with claim 11 wherein said diffuser comprises a body of light transmitting material having an outer surface comprising an array of horizontally extending lens surfaces and said inner wall includes means reducing transmission in a horizontal direction for enhancing the radiation from said diffuser in directions approximately 45* above and below the horizontal.

16. The combination in accordance with claim 15 wherein said horizontally extending pyramids have opaque inner walls extending parallel to the surface of the diffuser whereby light from lamps enters the diffuser through said walls of the pyramid structure and exits through the lens structure.

17. A fluorescent fixture assembly comprising a base; socket means secured to one side of said base for holding a U-shaped fluorescent lamp in a generally vertical direction; elongated ballast means mounted between said sockets to extend between the legs of said U-shaped fluorescent lamp and substantially obscuring the view of one leg of a U-shaped fluorescent lamp by the other; said ballast having a light reflective outer surface whereby the cooperation of said ballast in said U-shaped lamp produces a generally uniform light distribution in a horizontal plane.