CA2001111C - An indirect luminaire having a secondary source induced low brightness lens element - Google Patents

Abstract

An indirect lighting system having a generally visible light transmissive element, such as a prismatic lens element (31, 33) or a diffuser strip, which modifies the direction of the light incident thereon from a secondary light source, The lighting system has a primary light source (13, 14) and structural means as in a housing (21) for positioning the primary light source proximate a reflective surface (12) which reflects light back toward the light transmissive element and which thereby acts as a secondary source of light for illuminating this element. A light foil means such as vertical side reflector walls (45, 47) are disposed between the primary light source and light transmissive element for substantially blocking direct transmission of light to the latter from the former. The light foil means, by keeping primary source light from directly striking the light transmissive element, forces the observable brightness in this element to be induced substantially entirely by the reflected light from the secondary source.

Description

' ;:9 113/ 1 ~ I 4: 55 ~ 43f,q28~ L~w FRX 05 2~

1 TITL~ OF ~HE I~V~ ION
2 An Indirect Luminaire Having a Secondary Source Induced Low 3 BrightnQss Len~ ElemQnt ~C~ROVN~ OF TH~ ~Nv~ION
6 The present invention relates to indirect lighting fixtures 7 and system generally, and particularly to luminaires for indirect 8 lighting which employ lens element5 or other light transmi~ive 9 media as a visible ~ource of low brightne~s to parsons in indirect lighting environment~.
11 Indirect lighting, which is produced by reflecting light from 12 a light ~ource off a reflective sur~ace such ~ a wall or ceiling, 13 has long been criticized as producing a dull lighting environment, 14 sometimes re~erred to as a c~oudy day or ~uneral parlor e~fect.
Nonethele~s, lighting de~igners are increasingly con~idering 16 indirect lLghting ~ystems for various applications because of the 17 even illumination they provide and because they eliminate glare 18 as60ciated with direct lighting system~. Indirect lighting has 19 become parti~ularly advan~ageous in the open office environment where video display ter~lnal~ (VDT'~) are now prevalent and where 21 uncomfortable glare on VDT screen6 often produced by direct 22 lighting fixtures, such as the ubiquitous recessed ceiling fixtures 23 (called troffers), can lead to VDT operator fatigue and, ~ome now 24 believe, long term health problem~.
To overcome the perceived dull lighting environment produced 26 by conventional indirect lighting, indirect flxtures have been ' 81 I ~ 7 2~ ~ 3 i~ 53 0 L ~I W F FI ~ ~ I
2~

l devised with visible low brlghtness lens elements which give the 2 ob3erver of the flxture a p~rcep~ion or illu~ion o~ seeing the 3 actual source of ligh~. such a fix~ure i8 de~cribed ln U.S. patent 4 4,390,930 issued June 23, 1983, which dlscloses a linear extruded fixture for indirect lighting having len~ ~trips running along the 6 top of the fixture hou~lng's opague ~ide wall~ The lens 7 extensions of the hou~ing side wall~ have a prismatic surface 8 formed to direct a small portion of the light received from the 9 fixture'~ light source into normal vlewing angles below the plane lO of the fixture. Th~ resul~ing brightness of the visible lens ll surface i5 generally sufficient to give a perceptlon o~ source 12 brightne~s and as a result gives the ps~chologically more pleasing 13 effect of being able to visually locate the li~ht source, while 14 avoiding discomfort as~ociated with exce~sive brightness and glare 15 producing contrast brightne~.
16 Studies have shown a further psychological advantage to low 17 brightness len~ alements on indirect fixtures and particularly 18 linear indirect fluore~cent fixtures. It ha3 been found that the l9 low brightne~s lens element~ below certain maximum brightness ranges will actually tend to increase a su~ect's perception of the 21 overall light level in a space being illuminated ~y lensed indirect 22 fixtures. Accordingly, lensed indirect fixtures will permit 23 comfortable lighting at lower light levels re~ulting in lower 24 energy consumption.
Despite its advantages, lensed indireot ~luorescent lighting 26 ha~ heretofore ~uffered from the difficult problem of achi~ving ~19 19/1~ 14:58 2; 4364280 LFli~ FrlX 02 2~

1uniform brightne3~ ~n tha vl~ible fixture lenses. The principal 2problems are ~irs~ tha appearance of 600~et shadow~ on the ~urfaces 3of the len~ elements adjacent the elec~rical socke~ holders for the 4fixture's fluorescent lamp~, an~ secondly, uncontrollable 5brightness on particular prism ~urfaces a~ particular viewing 6angles. Socket ~hadows and local~zed areas of excessive brightness 7have bacome a particular problem with the advent of compact 8fluorescent lamp~ which are considerably smaller and have higher 9light output per unit length than standard slzed ~luore~cent lamps.
Exces~ive brightness in len~ed indirect fixtures frequently 11 occurs along the lens~ very top edge. It can also appear within 12 the body of the lens such as discussed in U.S. Patent No. 4,698,734 13 is~uéd October 6, 1987, which addresses the problem of side angle 14 lens brightnass, that is, hot spots on the lens produced by prior prismatic lsns designs at viewing angles other ~han a viewin~ angle 16 that i5 perpendicular to the lens surface. The above patent 17 discloses a solutlon to the side an~le brightness problem using a 18 lens design which to come degre~ sacrifices the len~' ability to 19 ~pread the light overhead the fi~ture.
~till a ~urther problam with lensed indirect lighting fixtures 21 is the abillty to control the overall lens brightness at normal 22 viewing angles (roughly from near horizontal to 45 degrees below 23 horizontal) at very low luminance levels. A~ above-mentioned, 24 studiQs have ~ound that a low brightness lens element on a len~ed indirect fixture can increase the perceived ligh~ level in the 26 indirectly lit environment. Generally, it is believed that lens 14: 5~ ~; 436'128~ Lnw F~IX ~3 2~3( ~

1 brightnes~ levels below approx.imately 400 footlamber~s will provide 2 a visually comfortable len~, however, ideally the lens brightness 3 levels ~hould be kept wi~hin lower brightness ranges o~
4 approximatel~ 50-200 ~ootlam~erts. with exi~ting lens indlrect lighting ~'ixturas, such low lumlnance level~ are very dlfficult to 6 achieve wit~ uni~ormity over th~ l~n~ surface.
7 The present lnvention overcom~s the above-mentloned problems 8 as~ociated with lensed indirect lighting by providing an indirect 9 lighting aystem having lens elements capable of belng maintained lo at very low brightness levels and having nearly absolute uniformity 11 of brightnsss over the entire observable lens ~urfacs. ~he present 12 invention eliminates distractiny ~ocket shadows on the lens and 13 producas a lens brightness level that tends to be self-adju~ting 14 with respect to the brightnsss levels on the overhead ce~lin~ or 15 upper wall surfaaes adjacent to which ~he lighting ~ixtures o~ the 16 system are suspended or mounted. That is, as the di~tance between 17 the fixture and the reflective sur~ace behind the fixture is 18 increasQd, both the brightnes~ o~ the background reflective surface 19 and the fixture lenses decrease. ~he reverse is ~rue if ~he 20 fixture to ~urface separation is decreased~

22 ~MARY OF ~H~ INVENTION
23 Briefly, the present invention provide~ for an indirect 24 llghting system having a generally vlsible llght transmissive element, such as a prismatic lens element or a d~fuser strip, 26 which modlfiss the direetion of the light incident thereon from a ' 8 ~ 1 5 ~ 3 ~ 4 ~ 8 ~ L rl ~J r ~ 4 1 secondary light source. The light~ng sy~tem has a primary light 2 source and ~tructural means for po~itloning the primary l~ght 3 source proxlmate a reflec~ive surface which reflects light back 4 toward the light tran~mis~ive element and which thereby acts as a secondary source of light for illuminating thi~ element. A light 6 foil means is disposed between the primary light source and light 7 tran6mi~sive element for substantially blocking direct transmlssion 8 of light to the latter from the former. The light foil means, by 9 keeping prlmary ~ource light from directly striking the light transmi6sive element, force~ ths observable brightness in this 11 element to be induced substantially entirely by the reflected light 12 from th~ ~econdary source.
13 Means are provided for causing at least a portion of the 14 secondary source light incident on the transmissive element to be directed into normal viewing angles for persons observing the light 16 transmi~sive element. As seen in the illustrated embodiments, such 17 mean~ include proper positioning of the light transmlssive element 18 and the llght foil means relative to the primary and secondary 19 light sources and can further include light refracting prisms on a lens media ~or focusing the dlstribution of light passing through 21 the lens. In one aspe~t of the invention, it is contemplated that 22 the light transmissive element will be pos1tloned to receive or 23 ~catch~ secondary source light on its interior surface and to 24 transmit the second~ry source light directly into the above-mentioned normal viewing angles. In this embodiment, the light 26 foil means is positioned inwardly o~ the light transmissive element 8~ 19 Is~ 43642~0 L~ l Fh)~ ~)5 l ~etween th1~ elem~n~ and the primary llght Bource. In another 2 aspect o~ the lnven~i~n, the ligh~ transmis~ive element is 3 positioned to receiYe or ~catch~ secondary so~rce light on its 4 exterior surface. In this embodiment the lig~1t foil means ~ncludes a reflector mean~ extending directly ~ehind the interior surface 6 of the light transmis~ive element so as to prevent any light, 7 primary or secondary BOUrCe light, from directly reaching the 8 inside Rur ace of the light tran~missive element. Rather, in this 9 embodim~nt, secondary 60urce light pa~es through the exterior surface of, and i~ then reflected ~ack out through, thi~ alement.
ll The light transmissive element of the inventlon will give a 12 pQrception of ~ource brightness by a virtue of the sec~ndary source 13 light passing through it and by virtue of the element's 14 modi~ication of the diraction of the secondary source light. The element is not transparent to the observer. The light passing 16 through the element appears to come ~rom the element it~elf rather 17 than being sur~ace reflected light.
1~ The lnvention's light transmi~sive element will pre~erably be 19 an elongate~ strip of lens positioned to extend along the side wall~ of the opaque housing of a luminaire for indirect lighting.
21 In accordancQ with the illustrated embodiment~ of the invention, 22 this lens strip can be positioned at the top o~ the housing, as in 23 the ca6e of the luminaire su~pended below an overhead ceilin~, or 24 along any top, bottom, or side perimeter of a luminaire housing or a wall mounted luminaire. In any case, the secondary source light 26 comes from the ceiling or wall surfaces nex~ to which the luminaire ' 8~ 15~ 436~1~8~ L~W FF:X ~16 i~ mounted.
2 W~ile the embodimen~s of the lnvention described and 3 illustrated herein pertain to di3crete linear fixture units which 4 can be used indivi~ually or connec~ed together in runs of ~xture~, it will be appr~ciated tha~ ~he invention i5 not limited to 6 discrete lensed indirect ~ixtures, whether of a linear or non-7 linear geom~try. For instance, an indirect lighting ey~tem in 8 accoxdanae with the invention might be achieved u~ing c~ve lighting 9 as the primary llght source, and uging zu~ ta~ly po~itloned lens elements and light foil means with the cove light~ng.
11 It is therefore seen that a p~imary objeat of the present 12 inventlon i~ to provide an improved lensed indirec~ lighting system 13 and luminaire having a low brightnes6 light transmissive element, 14 such a~ a lens strip, for providing a perception o~ source brightness in the space which is indirectly illuminated by the 16 luminaire~ o~ the system. It is a further object of the invention 17 to provide such a lensed indirect light~ng ~ystem and luminaire 18 wherein each light transmissive element o~ the system and lumina~re 19 has very low unifo~m brightnesa over ~he en~irety o~ itB visible surface, and wherein lens shadows, such as socket shadows are 21 eliminated, Other objects o~ the invention will become apparent 22 from the following detailed deEcription of the preferred 23 embod~ ment.

DE~C~IPTION OF T~E DR~WING~
26 FIG. 1 is a perspective view of a linear lensed luminaire in 'Ç~~ 113/l9 ~5~ 642~0 L~IIJ) F~ 97 l accordance with the invention;
2 ~IG. 2 iB a partial top plan vl~w thereo~;
3 FIG. 3 is a partial side elevatlonal view thereo~, 4 FIG. 4 is a cross-6ectional view thereof;
FIG. 5 ls an end elQvational view of a prismatic len~ used on 6 the luminaire of FIGS. 1-4;
7 FIG. 5A i~ a prism chart showing the prism angle~ ~or the lens 3 of FIG. 5;
9 FIG. 6 i~ a cro~s-sectional view of the luminaire of FIGS. 1-!Q 3, ~howing a two lamp ver~ion thereo~;
ll FIG. 7 is a cross-sec~ion ~iew of a wall~mounted version of L2 a len~ed luminaire for indirec~ lightlng in aa~ordanae with the 13 inventiont ~4 FIG. 7~ i5 a partial top plan view thereof;
FIG. 8 i~ a cross-section YieW of another wall mounted version 16 of a len~ed indirect luminaire ln accordance with the invention;
17 F~G. g iB a partial side elevational view thereo~;
18 FIG. 10 i~ a cross-section v~ew o~ an alternative embodiment 19 of a l~n6ed indirect luminaire in accordance with the invention 20 wherein a reflector element is placed directly behind the 21 luminaire's lens element for reflecting back seaondary source li~ht 22 incident on the exterior surfacQ of the element;
23 FIG. ll is a partial top plan view thereof; and 24 FIG. 12 is a side eleva~ional viaw of the prismatic lens 25 ~lement of the luminaire illustrated in FIGS. 10-11.

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1 DE~ ED DE~RIP~ION OF THE I~UBT~A~ED EMBODIMENT
2 Referring now to the drawing6, an~ specifically to the 3 embodiment of the invention illugtrated in FIGS. 1-~, an indirect 4 luminaire 11 has a primary light source in the ~orm of compact fluorescent lamps 13, 14 ~such as biax sold by the General Electric 6 Company removably mounted in lamp sockets 15 spaced at regular 7 intervals along the length of the luminaire. The lamp sockets are 8 suitably mounted in an elongate~ opaque housing 17 which has 9 oppo~ite upwardly extending side walls 19, 21, on ~he top of which are ~ormed lens mounting rims 23, 25 and inwardly extending 11 reflector 6upports 27, 29. Elonga~ed lens elements 31, 33 are 12 mounted to the housing side walls by securing the base 35, 37 of 13 the lenses to the support rims 23, 25. As best illustrated in FIG.
14 4, the lens elements extend laterally outwardly and upwardly in an arcuate shape away from the top of the housing 80 as to generally 16 face the overhead ceiling surPace 12. AB hereinafter described, 17 the overhead ceiling surface below whioh the luminaire 11 is 18 po~itioned will act as a secondary source of light for the 19 laterally extending len~es 31, 33 because of the ability of the surface to bounce or reflect light from the compact lamps 13 back 21 toward the luminaire.
22 The luminaire hou~ing 21 holds a ballasts 3~ and the necessary 23 electrical wiring (not shown) for electrifying the lamp sockets 15, 24 16. A generally defined top opening 41 a~ the top o~ the housing permits light from the lamps 13, 14 to emerge from the luminaire 26 in an overhead light distribution which illuminate~ the overhead ' ~ 13~ 1 ~ 15: 05 2~ 4~6q213g LRIl) Ffls~ ~
21'(~

ceiling surface 12 and any upper ve~tical wall surfaces (not shown) 2 in the vicinity of the luminai.re. Reflector means in the housiny 3 generally behind and to the E3ide of the lamps 13, 14 con~ist of a 4 bottom reflector plate 43, sultably a diffuse w~llte reflector, and 5 side reflector walls 45, 47. The slde reflector walls, which are 6 seen to extend substan~ially vertically upward from near the bottom 7 of the bottom re~lector pla~e 43 through the top opening of the 8 luminaire to approximately the maximum height of the lamp sockets 9 15, 16, and whiah ~uitably can be a specular surface with a ball p;ne h~ ~r texture, sometimes known as Elammertone reflectors, are 11 supported in their upright position by the side support bracket 12 structures 49, 51. These rsflector walls generally ac~ to reflect 13 light incident ~rom lamps 13 laterally of the luminaire to achieve 14 a widespread d~stribution of light overhead the luminaire. As will be discussed further below, the side reflector walls and supporting 16 structures will also act as a light foil means between the lamps 17 and lens elements for ~ubstantially blocking direct transmission 18 of primary sourae light to the lens elements.
19 With reference to FIG. 4, it can be seen that laterally extending lens elements 31, 33 catch secondary light reflected from 21 the overhead ceiling surface 12 as depicted by the light rays 22 denotQd by the letter "A." The side reflector walls 45, 47 permit 23 the~e secondary light rays to reach the lenses, but defeat the 24 ability of primary source light rays, represented by the letter "8,~ to do so. Therefore it can be seen that the brightness in the 26 lens elements is induced substantially entirely by the ~econdary ' ' '89 19,~19 1~:~6 2~ 436q28~ L~W F~

1 source of light ~rom the ceiling. B~cause the ceiling generally 2 provide6 a non-specular reflective 6urface, the diffuse nature of 3 the light from ~he secondary source will evenly illuminate the lens 4 elements over their entire length with the result that socket shadows and shadows created by other luminaire ~tructures, such as 6 source ba~fle element~, are eliminated. Also elim~nated because 7 o~ the dlffuse natur~ of the ~econdary 80urce light are local~zed 8 bright areas on the lans at all viewing angles.
9 It is noted that the exterior surfaces 32, 34 of the lens 10 elements 31, 33 are ~enerally seen by persons in the vicinity of 11 the luminaire at normal viewing angles which generally range from 12 high viewing angle, which is approximately hori~ontal if the person 13 is 6tanding far away from the fixture, to a low viewing angle 14 somewhat below horizontal for a person standing closer to, but 15 within line of sight of the fixture. A typioal viewing angle 16 within thi~ range is generally ~hown by the arrow denoted "VA" in 17 FIG. 4. A~ earliQr indicated, it i3 de~irable that within normal 18 viewing angles, the brightness of the exterior surfaces of the lens 19 elements bè maintained a~ very low levels, generally batween 50 20 and 200 footlam~erts. With the present invention, such lens 21 brightness levels can be uniformly obtained over the entire lens 22 surface by suitably spacing the lumlnaire 11 below the overhead 23 ceiling surface 12. The spacing will depend on the lighting 24 design, including the light output of the luminaire and the 25 reflectivity of the overhead ceiling surface. Generally, it is 26 believed that a bottom of fixture to ceilin~ di~tance of les~ than .

' 83 I~ 1 9 15: 06 ~; 436~8~ LF~W F~X ~ I

1 18 inches is not de61rable, in tha~, it will tend to produce hot 2 spots on the overhead ceiling which in turn may induce excessive 3 brightness in the luminaire~s lens elements. As the fixture is 4 moved away from the ceiling sur~ace, t~le len~ elemen~s will d~minish in brightness, with the maximum spacing being dlctated by 6 the observable brightness nee~ed in the lens elements to achieve 7 the desired perception of brightness in the lenses. It is ~ contemplated that luminaires of the type generally illustrated in 9 FIGS. 1-4 will be positioned below the ceiliny by suspending the lo luminaire or luminaires from the ceiling, or mounting the ll luminaires from other structures such as opposing vertical wall 12 surface~ or room partitions.
13 A particular lens element suitable for use in the FIGS. 1-4 14 luminaire i~ illustrated and described in FIGS. 5 and 5A. This lens element is an elonqated lens element having a uniform cross-16 sectional shape preferably fabricated o~ an extruded acrylic 17 plastic material. The visually active portion of the lens is 18 defined by the interiox prismatic surface 35 and the visible 1~ exterior sur~ace 32, 34. Thi~ portion extends generally outward ~0 and upward in an arcuate shape from the lens base 35, 37 which has 21 a mounting rib 40 pro~ecting ~rom the bottom thereof. The 22 pri~matic surface 35 on the interior of the lens is generally a 23 non-directional light diffusing prismatic configuration having 24 representative prism angles as shown in ~IG. 5A. It i9 understood, however, that the prismatic surface 36 of thi6 12ns can be modified 26 as desired to be directional for increasing or decreasing th~

/ 2 9 13 8: 2 5 2: 4 3 5 '1~ L ~
3~

1 amount of light directed into particular viewing or non-viewing 2 angle~ to the side of the lumlnaire.
3 In further reference to FIG. 4, i~ can ~e ~urther noted tha~
4 the directional~ty o~ the light emerging from the top opening 41 of the luminaire can bP enhanced by the unique use o~ a kicker lens 6 53 laid over the top of the bot~om reflector 43. This kicker lens 7 can ~uitably be o~ a flat Frennell len~ which will cause the light ~ reflected from the bottom refle~tQr to be concentrated in 9 particular directions, ~uch as concentra~ing ~he light off the reflector toward the vertlcal Hammertone reflector walls 45, 47 for 11 enhancing the widespread light distribution o~ the luminalre.
12 FIG. 6 illustrakes an alternative embodiment of the luminaire 13 shown in FIGS. 1-4 wherein ~he h~h intensi~y compact fluoresoent 14 lamps 13, 14 of th~ FIGS. 1-4 luminaire are replaced by two lower intensity fluorescent lamps 55, 57, such as standard ~ized T8 or 16 T12 lamp~. It will be readily appreciated that the invention is 17 in no way limi~ed by par~icular lamp configuration, and that 18 different types of lamps, including non~fluorescan~ lamp~, and lamp 19 configurations can be used in conjunction with the invention.
FIGS. 7-7A shows skill another embodiment of the invention 21 wherein the luminaire iB an asymmetrical wall mounted luminaire 22 generally denoted by the numeral 61, instead of a ~ymmetrical 23 lumlnaire as shown in FIGS. 1-4. In the F~G. 7 embodiment, the 24 luminaire is comprised of an asymmetrical opaque housing 63, ballast 65 positioned at the back of the housing, and high 26 intensity compaot ~luorescent lamps 67 serving a~ the luminaire's ' 8'3 ~ 15: ~7 ~5: 436428~ L~W FR% I ~
~}(3~

l primary llght source. A housing back wall 6~ extends upward behind 2 the light source to serve as a mounting sur~ace for m~unting the 3 luminaire by 5uita~18 bracket mean~ against a vertical wall surface 4 (not shown). The hous~ng, which extends away Prom ~hls back wall outward and then upward about the light source in a double 6 convoluted shape, additionally provides an opaque side wall 71, the 7 end of which raceives, by means of a snap-in engagement, elongated 8 lens element 73. It can be seen that the lans element 73 generally 9 provides an extension of ~he shape of the housing slde wall 71 up to approximately the height of the biax lamps.
11 A shaped re~lector 77 for reflecting light up through ~he top 12 opening 79 of the FIGS. 7-7A luminaire and which i5 mounted within 13 the housing 63 on reflector mounts 81, 83 extends generally from 14 behind the compact fluorescent lamps forwardly to the base 74 of lens element 73. The extreme end 75 of the reflector is bent 16 upward to provide a llght foil means for the lens element 73, that 17 is, a means for preventing the light fxom the biax lamp 67 from 18 being directly received by the lens element. Additionally, a back 19 reflector strip 85, positioned in oppo~ition to the lamp sockets ~6, 68, is secured inwardly of the extended end 75 of the reflectox 21 at an angle which increases the amount of ligh~- reflected back 22 against the vertical wall surface against which the luminaire is 23 mounted in areas adjacent the lamp sockets 6~, 68. Back reflector 24 strip 85 acts to illuminate dark areas on adjacent wall surfaces created by the presence o~ the lamp sockets.
26 It will be understood that light ~rom the luminaire of FIGS.

~89 Ic~ 15:0~ :!; 4364280 L~IW Fax ~13! J~

1 7 and 7A will be directed ~hrough the luminaire~s top opening 79 2 against upper wall and overhead ceiling surfaces (not shown) which 3 will in turn send some light bac~ toward the luminaire to 4 illuminate the lens element 73 positionecl behind the light foil 75.
As described in connection with the FIGS. 1~4 embodi~ent of the 6 invention, this will cause the brightnesg in this lens element to 7 b~ induced substantially en~irely by ~he secondary source light.
8 FIGS. 8 and 9 illustrate another wall mounted version of the ~ invention wherein the llght transmissive media for receiving t~e lo secondary source ligh~ is provided at the bottom rather than the ll top of the luminaire. With reference to FIGS. 8 and 9, a wall 12 mounted luminaire 87 has an elongated opaque housing 89 and a 13 ballast 91 mounted in a top cavity 93 of ~he housing. The housing 14 extends downwardly from the ballast to ~orm a lower opaque side wall 95 to which an elongated lens element 97 is attached and of 16 which the lens element form~ a geometrically plea~ing extenslon.
17 The luminaire~s primary light source consi.sts of compact 18 fluorescent lamps 99 mounted proximate the top of the luminaire 19 beneath the ballast 91. A shaped reflector lOl extends from behind the lamps 99 downward along the downward extension of the housing ~l until it rQaches the base 98 oP the lens element. ~t this point, 22 the extreme end of the reflector is bent inward and slightly upward 23 to form a light ~oil means for the lens element g7, again to 24 prevent primary source light from directly reaching the lens. It can be appreciated that the shaped reflector ~01 direats some of 26 the light from the primary llght source o~ thi~ ~mbodiment of this '89 1il~i9 15~9 ~ 43642~:3 L~l~l FFIX 14 2~ J~

1 luminaire against the ver~ical wall surface 103 to which the 2 luminaire is mounted. (The fix~ure is mounted by sui~able brackets 3 (not shown) or from the ceiling.) ~ substantial portion of this 4 light will be reflected toward the luminaire and specifically to the lower lens element 97 which wlll transmit the light to induce 6 brightness in the lens. It i8 contemplated that lens element 97 7 will have an interior prismatic ~urface for providing a generally 8 light diffusing prismatic lens which can be seen by observers in 9 the vicinity of tho luminaire when the bottom of the lum~naire is substantially at the ob~erver~s ey~ level or above eye level. As 11 in the other embodiments of the invention, this len~ element will 12 provide the observer with a perception of seeing source brightness 13 whereas otherwise the observer would ~ormally only generally be 14 aware of indirect lig~t from walls and ceilings withou~ the perception of seeing the source producing the indirect li~hting.
16R~ference is now made to F~GS. 10-12 and the luminaire shown 17 therein. Luminaire 105 has a primary light source in the form of 18 biax lamps 107, an elongated opaque housing 109 having upwardly 19extending aide walls 11~, 113, and a ballast 115 placed in the bottom of the housing. Elongated, arcuate lens elements extend 21 generally upward and inward from the top of the housing side wall~
22 so as to compliment the shape of the housing. A reflector 121 23 disposed beneath the light source has substantially ver~ical side 24 walls 123, 12~ disposed sl~ghtly inward o~ the lens element 117, 119 and extending upwar~ to near the top of the lense~. As 26 discussed in aonnection with earlier ambodlments of the invention, '8~ 10~ 15: 1~ ;!; 43~428~ L~W FFIX 15 Z~

1 the reflector, including its vertical side walls, act to direct the 2 primary source light g~nerally upward and laterally of the 3 luminaire through the luminaire~s top opgning 127 to illuminate an 4 overhead ceiling sur~ace ~elow which ~he luminaire is suspended or otherwlse mounted.
6 As best seen in FIG. 10, a ~econd reflector element 129, 131 7 is inserted directly behind each of t~le elongated lens elements.
8 It can be 6een that the lens elements are, in this embodiment of 9 the invention, positioned such that secondary light reflected back 10 from an overhead ceiling surface will stxike the exterior surface ll 133, 135 of the lenses, rather than the interior surface as in 12 previously described versions of the invention. The reflector 13 elements, 129, 131 behind the lens elements will act to reflect the 14 secondary light passing ~hrough the lens elements back out through 15 the lens as i~ the light were coming from within the luminaire 16 housing itself. ~his secondary source of light will, in turn, 17 induce in the lens elements a uni~orm bri~htness without shadows 18 or hot spots.
l9 Referring t~ FIG. 12, the lens of the FIGS. 10 and 11 20 e~bodiment of the invention is generally an elongated extruded 21 acrylic prismatic lens having a prismatic surface 137 on the 22 interior lens surface. ~s shown in FIG. 12 and the prism angle 23 chart associated therewith, the prism angles for the prismatic 24 surface 137 can be chosen so that the lens element acts as a light 25 distribution control element for laterally spreading the li~ht from 26 the luminaire to achieve a more widespread overhead light ' 89 lû/ 1~ 15~ 1 1 2S 43f>4281~ L~W FûX
2~

1 distribution pattern.
2 It is noted that the lenses 133, 135 of ~he FIGS. 10-12 3 luminaire have a base end 139, on which there is formed a 4 downwardly pro~ecting mounting rlb 141, and an upper end 143 having a groove 145 for receiving and holding the top e~ges of the 6 reflector elemen~s 129, 131. The upper end 143 of the lens is a~so 7 preferably made to be opaque, such a~ by means of an opaque co-8 extrusion. The opacity in the end of tip of the lens will prevent 9 any possible streaking a~ the top of the lens caused by direct 10 light from the hi~h intensity ~iax lamps 107.
11 It can therefore be seen that the present invention is a 12 lensed system and luminaire for indirect lighting which provides 13 uniform lens brightness over the visible ex~erior surface of the 14 lenses and which eliminates distracting shadows or localized bright 15 areas in the lenses. Although the present invention has been 16 described in considerable detail in the foregoing specification, 17 it is under~tood that the invention is not in~ended to be limited 18 to such detail, except as necessitated by the following claims.

Claims (11)

1. A system for indirect lighting comprising a primary light source for indirect lighting, structural means for positioning said primary light source proximate a reflective surface whereby said reflective surface acts as a secondary source of light, at least one generally visible light transmissive element which modifies the direction of light incident thereon, said light transmissive element being positioned to receive reflected light from said secondary source of light, means for causing at least a portion of the secondary source light incident on said light transmissive element to be directed into normal viewing angles for persons observing said light transmissive element, and light foil means disposed between said primary light source and said light transmissive element for substantially blocking direct transmission of light to said light transmissive element from said primary light source whereby the observable brightness of said light transmissive element is induced substantially entirely by said secondary source of light.

2. The indirect lighting system of claim 1 wherein light transmissive element is a prismatic lens.

3. The indirect lighting system of claim 1 wherein said light transmissive element is a light diffuser element.

4. The indirect lighting system of claim 1 wherein said light transmissive element is positioned proximate said primary light source.

5. The indirect lighting system of claim 1 wherein said reflective surface is situated generally overhead said structural means and said light transmissive element is positioned generally below said reflective surface proximate said primary light source.

6. A luminaire for indirect lighting comprising a primary source of light, a housing having at least one opaque side wall and an opening to permit light from said primary source of light to be directed from said luminaire for illuminating a reflective surface proximate thereto whereby said reflective surface acta as a secondary source of light directed back toward said luminaire, at least one generally visible light transmissive element which modifies the direction of light incident thereon, said light transmissive element extending from said housing side wall to receive reflected light from said secondary source of light, means for causing at least a portion of the secondary source light incident on said light transmissive element to be directed into normal viewing angles for persons observing said light transmissive element, light foil means disposed between said primary light source and said light transmissive element for substantially blocking direct transmission of light to said light transmissive element from said primary light source whereby the observable brightness of said light transmissive element is induced substantially entirely by said secondary source of light.

7. The luminaire of claim 6 where said light foil means includes a reflector strip extending generally from said housing side wall in the direction of said housing opening and inwardly of said light transmissive element.

8. The luminaire of claim 6 wherein said light transmissive element has an interior surface and an exterior surface, the latter of which is visible at normal viewing angels, said light foil means is spaced inward of said light transmissive element, and said light transmissive element extends from said housing side wall so that reflected light from said secondary light source is incident upon the interior surface of said light transmissive element.

9. The luminaire of claim 6 wherein said light transmissive element has an interior surface and an exterior surface, the later of which is visible at normal viewing angles, said light transmissive element extends from said housing side wall so that reflected light from said secondary light source is incident upon the exterior surface of said element, and said light foils means includes reflector means extending behind the interior surface of said light transmissive element so that at least a portion of the light passing through said element from said secondary light source is reflected back through said element into normal viewing angles for said luminaire.

10. A luminaire for indirect lighting comprising a primary source of light, a housing having at least one opaque side wall extending upward about said primary light source and a top opening to permit light from said primary light source to be directed from the luminaire for illuminating a generally overhead reflective surface whereby said reflective surface acts as a secondary source of generally downward directed light, at least one lens element secured along the opaque side wall of said housing, said lens element extending from said side wall so as to receive light from said secondary source of light and directing at least a portion of said received light into normal viewing angles for said luminaire, and a light foil means disposed between said primary source of light and said lens element so as to substantially block direct transmission of light to said lens element from said primary source of light whereby the brightness of said lens element is induced substantially entirely by said secondary source of light,

11. The indirect luminaire of claim 10 wherein said light foil means is comprised of at least one reflector element disposed generally behind said lens element to reflect light from said primary source of light generally upwardly through the top opening of said housing and away from said lens element.