US2312618A - Fluorescent tube lighting fixture - Google Patents

Description

March 2, 1943. M, B BECK 2,312,618

FLUORESCENT TUBE LIGHTING FIXTURE `Filed Nov. 16, 1940 2 Sheets-Sheet l INVENTOR. MoRms B. BECK.

TTORNEYS.

March 2, 1943. M, B BECK I FLUORESCENT TUBE LIGHTING FIXTURE` Filed Nov. 16, 1940 2 Sheets-Sheet 2 Patented Mar. 2, 1943 UNITED STATES reni orsi 3 Claims.

YThis invention relates 4generally to lighting fixtures, Yand more particularly tolightingiixtures of the semi-indirect type, vthat is, xtures in which one Apart of the luminous output passes `directly and without reflection to the wor-king plane, while another part reaches the :working plane only after-reflection.

vMy invention relates particularly toa xture employing fluorescent tubes as the light source. For this reason my invention has been disclosed as -employingsuch light-source; it will be understood, however, that features of my invention may serve advantageously with other types Aof light source.

'The general object of myinvention is the pro- 'vision of a lighting xture which is compact, simple in construction and inexpensive to make and maintain and which affords effective light distribution, and in which the eiciency is high, due to the minimization of losses such as absorption losses where fluorescent tubes are used.

Among the more particular objects of my in- -vention is the provision of a uorescent'lighting tube xture which is arranged in relatively close Yproximity to the ceiling but in which neverthe- -less eiective and uniform lightrdistribution is attained, and in which, further, eiective means for reducing glare is provided.

-Another object of my invention is `the provi- --sion in a fluorescent tube lighting fixture `in which a uorescent tube is positioned in relatively close proximity to a -fsurface such as a ceiling, of means for dividing the luminous output of said tube into portions directed respectively toward and away from said surface, the '.division being Velected substantially by a, .plane inclined to said surface.

Among the morefparticular objects of .my invention is furtherV the provision in -aviiuorescent -tube lighting xture of fmeansfor dividing the light flux of `a uorescent tube'arranged in parallel relation to a reecting surface,.such-as va wall or ceiling, in such a manner that .aportion thereof will be directedtoward thesaid:surface,` `but in general 4at an anglethereto, soithat the:-

Vdistribution of light on said surface.V is asymmetrical relatively to a plane perpendicular to Ythe surface and passing through the tube axis, While the remainder of the light ux is directed Another Lobject of -my invention relates tov -'the provision `in a lighting xturercom-prising `a plurality of fiuoresoenttubes arranged iii-.parallel y K dao-n to each otheryand to a surface, andze' tion. :Withingthefhollow.;ofithe.;:Ganiuyi the distribution offjjgh S `means for eliminating glareifrom ,theft invention;

.scale taken substantiallyzinthe Plaueiind Vsupportingthe endsgof thetubes.:

said tubes being arranged in-.'.g'roups of .means associated with each :of said -groups S'soias to secureV -the .asymmetric distribution :described the roregoinglparagraph, and .said 'groups being so positioned .Lthatthealight ifluxi'rom vthe 1Mo, groups will interact inaipredeterminedzmanner. In particular it is ian .object .of .my ,invention to arrange two such groups so that the lglit iiux from each group .is .divided into .two-p0rtions, the line of separation orid'nfisioncheb-Wisten these .two portions .being located :inia .plane i13- two groups meeting at anxanegle the eapexf,

which is directed.itowardsthelsurface.

.n is alsexan` ebiectef .my invention. .to prooi/idev in a lighting xture of the character escribed .These objects :and such 1otherobjectafzaslwll .hereinafter 4appear .for :be 'zpolniied 91.11?, ti'l'ctained in :the illustrative embodiments of :ny

inventienfshownin tnegdrawines: in which .Figureiis aside elevational .view of 1a. .ii-ng xtureconstructed: in agrdlle Wit ,312V

.Figure zfis a fbettonrnlanmiewthereon Figure is an .vendlevatiflnafl 'NeWnhSIQQ Figure 4 is a transverse sectional view subinthetdirection ofithegarrow; vl Figure .5 ,is a Vsectional `.viewigon 1am-enlarged' bythe line ses.ofFigureiieolnnginiiheidir tion ,or theyarrows; Y

figures isa transverseeseetinal ewso ref spendi-neto .a .portionuof Figure "f1, enlarged scale, pandfshowng 1 i modified: f-@Tmfpf mvinvention;

Figure 7 is a fragmentary.viewtalsenisubstae- .muy ,in June planer indicated i by .fthe gime zi- .oFigurelGi-and Figure 8 iis a fdiagra..;rnatc View. illustre-titl typeshown in yFigune-s. il to me 1mi-11 ,anow :proceed o', desc 'l2 construction :of -the'g'illlustrated .whereinbraokets Be-.Land ,f porting e the ends :,ofA theVY tubes.

and sirmlar'brackets Bf.

These brackets .extend @don/inwardly; andzlaterelly -from a ,canopy C.whichmaivfibe supportedpfrqm :the ceiling, and which ,hasefreflectinggsuriaces in and l-I .fprovidedat.fitsssde aand reflecting surfaces l2 and I3 disposed on its .bott Qrimay be disposed the conventional auxiliary apparatus. It will be observed that the reflectingr surfaces I and Il are concavely contoured in transverse section.

'I'he brackets B-I and B-2 may be made hollow as shown in Figure 5, as by being constructed of an inner shell I4 over the side portions I5 of which fits an outer shell I6. This produces a passageway between the shells through which the wiring I'I from thesockets I8, carried by the shell I4 and in which the tubes are mounted, may be led into the canopy C.

Intermediate the fluorescent tubes F-I and F-2 is shown a member I9 of generally diamond shaped cross-section, which-serves to connect the brackets B-I and B-Z, and the outer surfaces of which are formed as reflectors adapted to reect the light from the tubes. ing and connecting member is positioned between the uorescent tubes F-3 and F-4 and Aperforms a similar function.

Reflecting and supporting members 2l and 22 fserve similarlyto connect the end portions respectivelyof bracketsB-I and B-2 and brackets B-3 and B-.4, while their inner surfaces act V as reflectors. These members also act as glare shields, as will be more fully explained hereinafter.

Considering the fluorescent `tube F-I and the adjacent reecting members I9 and 2I, it will be observed that the cross-section of these members is generally diamond shaped and that their i axes lie in the same plane as the axis of the fluorescent tube, and, further, that a pair of opposedapices of said reflecting members also lie in said plane. Y Y -The surface of the uorescent tube F-I will i consequently be divided substantially into .two portions by the'adjacent apices I9a and 2Ia of "the reflecting members I9 and 2l, and this di.`

vision will be more nearly effected the closer these apices lie to the fluorescent tube surface. As a result the light flux of the fluorescent tube F-I will also be divided substantially into two portions, because the light emission in a'fiuorescentl tube takes place at-the inner surface of the glass r tube. 1 1

While theory would seem to indicate that close contact of the apices with the wall of the uorescent tube is desirable, in practice, due to irregularities and inaccuracies in the parts, and 'the requirement of liberal tolerances so as to keep manufacturing costs within reasonable limits, it is found that a slight spacing between the i apices andY the tube wall is not merely required;

but lis also desirable. I have further found that a slight rounding off of the apices is desirable, j as 'shown in the drawings.

"The light flux emitted above the apices I9a and 2 Ia must remain above the plane of the fluoresl' cent tube axis', that below the said apices must remain below the said plane. i I

The reflecting walls of the members I9 and 2 I,

' which are inclined to the said plane, and which .By reference toFigure 5 it will be 'observed that- A similar reflect` furthermore may be slightly concaved so as to the reflecting and supporting member 2I has been shown of hollow tubular construction, a plug 2 Ib being shown secured within its end portion, and this plug may be secured to the shell I4 in any suitable or preferred manner, as by a screw 2 Ic. Obviously this construction combines lightness in weight with sufiicient strength, where a suitable material is used. It is understood, of course, that the other reflecting members I9, 20 and 22 may be of similar construction.

The distance between the vertically spacedA apices of the tubes 2I and 22, which do not function to prevent absorption losses is determined mainly by the function of these tubes as glare shields. Forv the sake of uniformity of appear- Y ance and also because of simplification of manufacture, this dimension may be, as shown in the drawings, the same for tubes 2| and 22 as it is for tubes I9 and 20.

The reflecting surfaces I2 and I3 function to direct Vthe light from the respective tubes F--2 and F-3 downwardly as far as possible and without redirecting it into the tubes. For this purpose they are appropriately curved, as shown.

Attention is now invited to Figure 8 which attempts, diagrammatically, to indicate the light distribution that is obtained with a fixture of the Vtype just described.v The fixture is shown diagrammatically in transverse section, and the distribution in a plane transverse to the fixture is shown. This distribution is representative of the distribution of the fixture and gives an adequate idea ofr its functioning.

It will be observed in general, as has already been pointedout, that since the plane dividing the light flux from the tubes F-I and F-Z'is inclined'to the horizontal, one portion of the light flux will be thrown upwardly against the ceiling at an angle thereto, and due to this angular inclination of the light flux to the ceiling it will bereflected at an angle downwardly and 4laterally and away from the fixture, instead of directlydownwardly as would be the case if the Yplane ofthe axes of fluorescent tubes F-I and F-2 were horizontal. The light flux on the ceiling is distributed asymmetrically and the same is true of the distribution inthe working plane or on the floor after reflection. A further effect of this asymmetric distribution is that the greater portion of the light flux will not strike the canopy C. f

Another portion of light ux will be thrown downwardly but also generally at an angle to the vertical. VVThe flux proceeding directly from the tubes F-I; and F-Zwill diverge in a downward direction;` this divergence will belimited by the reflecting members I9 and 2IV which willv divert -rays striking them in a direction more or Vless perpendicular to the said plane containing the axes of Vtubes F-I and F-2, that is 'in a downward direction but at an angle to the vertical which leads them beneath the other set of tubes F-,3 and F'-4. i

The reflecting surface I2, as already stated, is preferably designed so as to reflect as much of the light from the tube F-2 as possiblein a downward direction, and reflection back into the tube is avoided as .muchas possible since such reflection "back into the :tube causes a loss of light due to the absorption of the reflected rays.

The 'actionthat has been described for the tubes F-I and F-Z is identical with that of the tubes F+3and F-lI, except ofcourse that the rreflection andlight emission occur atangles to the vertical that are -opposite to `the angles atl ing.

'andere 'which the iight Vfrom the tubes F-i distributed.

The foregoing general discussion will be made and Iii-'2 -is which has the lighting fixture carrying tubes "F-I, F-Z, F-3 and F--ll mounted thereon, and -below the ceiling is shown the floor, in section,

and above the floor the Working plane.

- The light ray 30 indicates roughly the limit 'to the right, of direct rays from the fluorescent -tube F-S; its point of intersection with the 'working plane is not shown because it falls outfside the limits of the ligure. vwhich pierces the working plane 32 and strikes The light ray 3|,

the floor at 33, represents roughly the limit, to the left, of the direct rays from the tube F-ll. The limits at both sides, of the rays reflected from the reflecting members 2li and 22, and from the reilecting surface I3, is indicated approximately by the rays 3 and 35, these rays piercing the Working plane respectively at the points 3% and 37 :and striking the floor at 38 and 39.

Thus far only rays passing downwardly have been described. Upwardly moving rays will now be discussed. At @il and 4l are indicated light rays proceeding respectively from the tubes F-B and F-d and directly striking the ceiling, from which they are reflected as rays l2 and d3 respectively, and these rays mark approximately the limits, at both sides, of the rays that proceed directly from the tube F-B and F-ii to the ceilworking plane lies outside of the diagram, and gives an indication of the spread or the light flux from the fixture. The intersection of ray 43 with the working plane is shown at 43a. Rays 44 and t5 represent rays intermediate the limiting rays d and fill. Their reflections from the ceiling are the rays 46 and l1 respectively, the latter piercing the working plane at d8.

At 139 is shown a ray proceeding from the tube F-l and striking the reflecting surface Il on the side wall of the canopy C. This ray will be reflected from the surface l l as the ray B.

The eifect of the reflecting members 29 and 22 on the tube F-4 is indicated by the limiting rays 5l and 52 which strike the ceiling and are reflected therefrom in the form of rays 53 and 54 respectively which pierce the working plane at the points 55 and 56 respectively It will be observed that light thrown upwardly and laterally from tube F-3 and F-li will be reflected downwardly and laterally to the left of the iixture, while light proceeding downwardly from the tubes F-B and F-d will travel downwardly and laterally to the right and underneath the tubes F-l and F-2.

It is to be understood that the light distribution of the tubes F-I and F-2 will be similar to that described for the tubes F-3 and F-, but the lateral component of movement of the light will be in the opposite direction, from that described for the tubes F-B and F-.

In this way it will be seen that the two sets of tubes supplement as well as augment each other in their illuminating action. Any lack of uniformity in the illumination obtained on the working plane by any one fixture will be corrected more or less by adjacent fixtures, which are suitably spaced from each other for that purpose.

The second requirement for eicient illumina- The intersection of the ray d2 with the tion -is that relating to protection against glare. It will be observed from `Figure v'8 that to `an observer situated laterally of the fixture the reflecting members 2l and 22 serve to shield the fluorescent tubes from the direct rgaze of -th'eobserver in certain positions. To increase their shielding effect they may be made wider in a vertical direction. As the observer approaches the area directly underneath the fixture the inner reflecting tubes I9 and-20 contribute to the shielding effect, although complete shielding by these means cannot be obtained. However, since an observer positioned underneath the fixture will seldom look upwardly at an angle at which he will look directly into the fiuorescent tubes additional shielding may in many cases be dispensed with.

Where, however, such additional shielding -is necessary, I may 'provide a system of louvers as indicated in Figures 6 and 7 by way of example.

In Figure 6 is shown a portion of a bracket P--l, corresponding to bracket B-E, von vwhich are mounted iluorescent tubes G--l and G-2, corresponding to the tubes F-l and F-2, and further reflecting members 19 and 3l, corre'- sponding vrespectively to the reflecting members I9 and 2i. To this structure is added on the lower side a system of louvers in the form cfa grill comprising plates 32 running longitudinally and plates 3.3 running transversely. These plates, it will be observed, are disposed generally in the direction of the light iux, whereby their obstructive effect is a minimum.

By the use of such a system of louvers, glare to an observer positioned beneath the fixture 'is almost entirely eliminated, and, further, absorption of light is reduced. For instance, from Figure 4 it will be seen that light from tube F-''I can reach tube F-4. The louver system just described would prevent this.

Itwill be readily understood that while the fluorescent tubes have been described as parallel to the ceiling that the aims of my invention might also be obtained bypositioning of the tubes otherwise. For example, the tubes of each of the groups, say F--I and F--2, might be positioned at right angles to their positions as shown in the illustrative embodiment. While the dimensions and appearance of the fixture would be changed, the asymmetric character of the light distribution would be more or less retained. Obviously instead of using two tubes in each of the groups of tubes, the purposes of my invention would also be served by using less than that number or more than that number.

It will further be clear that the xture is also adapted for use as a wall bracket, the indirect illumination in this case being obtained by reflection from a wall instead of a ceiling.

While I have herein disclosed illustrative embodiments of my invention, it will be understood that my invention may be embodied in many other forms, as will be obvious to those skilled in the art, without departing from the spirit thereof. It will further be understood that the disclosure made herein of details of construction is by way of illustration merely and is not to be interpreted in a limiting sense, and that I donot intend limiting myself other than as called for by the prior art.

Having thus described my invention and illusstrated its use, what I now claim as new and desire to secure by Letters Patent is:

Y1. A fluorescent tube lighting fixture comprising a canopy and a pair of spaced apart brackets carrled thereby for supporting two pairs of fluorescent tubes in V-formation with the axes of each pair lying in a plane inclined to the horizontal and at an angle to the plane of the axes of the other pair to give the aforementioned V-formation and a substantially diamond shaped reflecting member mounted between the tubes of each pair to present a pair of opposed apices in the said inclined plane of the axes of the pair of tubes between which it is positioned and substantially bridging the space between said pair of tubes whereby the luminous flux from said tubes striking said reflecting member will be divided into two portions one of which will be' directed generally upwardly and outwardly of the xture, while the other one will be directed oppositely to said upwardly directed portion of the luminous flux, and an elongated reflector laterally concave in cross-section mounted above said brackets in parallel relation to tubes mounted therein, and

serving to deflect a portion of said upwardly directed flux outwardly of the xture.

2. In a fluorescent tube lighting xture: a canopy and a pair of spaced apart brackets carried thereby for supporting two pairs of fluorescent tubes in V-formation with the axes of each pair lying in a plane inclined to the horizontal and at an angle to the plane of the axes of the other pair to give the aforementioned V-formation and a substantialy diamond shaped reflecting member mounted between the tubes of each pair and presenting a pair of opposed apices in the inclined plane of the axes of the pair of tubes between which it is positioned and substantially bridging the space between said pair of tubes whereby the luminous flux from said tubes striking said reflecting member will be divided into two portions one of which will be directed generally upwardly and outwardly of the fixture, while the other one will be directed oppositely to said upwardly directed portion of the luminous flux, and an elongated reector downwardly concave in cross-section mounted above the upper one of said tubes in parallel relation thereto and serving to refiect a portion of the light thereof downwardly.

3. A fluorescent tube lighting fixture comprising a canopy and a pair of spaced apart brackets carried thereby for supporting two pairs of uorescent tubes in V-formation with the axes of .each pair lying in a plane inclined to the horizontal and at an angle to the plane of the axes of the other pair and a reiiecting member mounted between the tubes of each pair, said reflecting member being of substantially quadrilateral cross-section with a pair of opposed apices lying in the plane of the axes of said pair of tubes and substantially bridging the space between said tubes whereby the luminous fiux from said tubes striking the said reflecting member will be divided into two portions one of which will be directed generally upwardly and outwardly of the fixture, while the other one will be directed oppositely to said upwardly directed portion of the luminous fiux, an elongated reflector laterally concave in cross-section mounted above said brackets in parallel relation to the tubes mounted therein and serving to deflect a portion of said upwardly directed flux laterally outward of the fixture, and an elongated reflector downwardly concave in cross-section mounted above the upper one of said tubes in parallel relation thereto and serving to deflect a portion of the light of said tube downwardly.

MORRIS B. BECK.

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