Reflector with textured inner surface and prismatic outer surface

Information

  • Patent Grant
  • 6494596
  • Patent Number
    6,494,596
  • Date Filed
    Tuesday, June 13, 2000
    24 years ago
  • Date Issued
    Tuesday, December 17, 2002
    22 years ago
Abstract
A reflector for a lighting fixture comprising a substantially bell shaped reflector wall with top and bottom openings and a substantially parabolic cross-section. The reflector wall includes an inner surface having a first top portion that is textured for diffusing light rays from the light source of the fixture, and a second bottom portion that has a smooth surface allowing the light rays to pass through the reflector. The reflector wall also has an outer surface with a plurality of curvilinear prisms for reflecting the light rays. The inner and outer surfaces of the reflector create an even distribution of light emanating therefrom.
Description




FIELD OF THE INVENTION




The present invention generally relates to a reflector for a lighting fixture. Specifically, the reflector has a portion of its inner surface that is textured to diffuse the light rays from the light source of the lighting fixture, and an outer surface with a plurality of prisms that reflect the lights rays, creating an even dispersal of light.




BACKGROUND OF THE INVENTION




A reflector for a lighting fixture, in particular a surface of revolution type reflector, reflects light from the light source of the fixture in an attempt to produce even illumination on a surface perpendicular to its axis of revolution. Surface of revolution style reflectors are easier to make than other reflectors, such as square or rectangular shaped reflectors. In addition, surface of revolution style reflectors can capture and redirect a greater amount of light with a smaller sized reflector.




However, the prior art surface of revolution reflectors tend to reflect light rays parallel to the axis of revolution, usually downward, and those light rays tend to overwhelm any light projected outwardly away from the axis of revolution, thereby causing a hot spot or spike in the intensity distribution of the reflector which prevents even illumination.




Also, the prior art reflectors fail to counteract the portion of the inner surface of the reflector that is closest to the light source, which contributes the most to creation of hot spots. These hot spots result in light puddles, or bright areas of illumination, and a general uneven overall illumination. In addition, as a consequence of hot spots, in the illumination, smaller fixture spring to mounting ratios are calculated and such that prior art downlights must placed closer together to evenly illuminate a certain area.




Prior attempts to avoid the problem of hot spots, such as varying the location of the light source, have resulted in additional hot spots or undesirable voids in the lighting distribution. In addition, shape variances in the prior art reflectors, light source tolerance, and mounting hardware tolerances can lead to inaccurate light source positioning, increasing the potential for hot spots or voids. Thus, the prior art reflectors require that the light source be critically placed in a specific orientation and location to avoid additional hot spots and voids in the light distribution.




Examples of prior art reflectors are disclosed in the following U.S. Pat. No. 1,412,315 to Correll; U.S. Pat. No. 1,543,606 to Harrison; U.S. Pat. No. 1,891,846 to Stauber, Jr.; U.S. Pat. No. 2,132,784 to Guth; U.S. Pat. No. 3,825,742 to Levin; U.S. Pat. No. 4,285,034 to Sullivan; U.S. Pat. No. 4,987,524 to Miller; and U.S. Pat. No. 5,957,565 to Hofmann.




SUMMARY OF THE INVENTION




Accordingly, an object of the present invention is to provide a reflector for a surface of revolution style light fixture, such as a downlight, that provides an even distribution of light.




Another object of the present invention is to provide a reflector for a downlight that avoids hot spots and voids in the distribution of light from the light source simply, efficiently, and inexpensively.




A further object of the present invention is to provide a reflector for a downlight that allows movement and varying of the placement of the light source while avoiding hot spots and voids in the distribution of light.




A yet further object of the present invention is to provide a reflector for a downlight that allows several downlights to be installed further apart even when the ceiling or mounting surface is low.




The foregoing objects are basically attained by a reflector for a lighting fixture having a light source, comprising a reflector wall including, opposing first and second ends, the first end having a first opening disposed therein, and the second end having a second opening disposed therein, the second opening being substantially larger than the first opening, an inner surface, the inner surface including, a first portion located adjacent the first opening and remote from the second opening, and having a textured surface for diffusing light rays from the light source, and a second portion being located adjacent the second opening and remote from the first opening with the second portion being substantially larger than the first portion, and having a smooth surface, and an outer surface having a plurality of curvilinear prisms thereon extending between the first and second ends for reflecting light rays from the light source.




By structuring the reflector in this fashion, light rays from the light source are diffused by the inner surface of the reflector at the particular problem area portion of the inner surface and reflected by the outer prismatic surface, resulting in an even distribution of light.











BRIEF DESCRIPTION OF THE DRAWINGS




Referring to the drawings which form a part of this disclosure:





FIG. 1

is a bottom perspective view of a reflector and a mounting and support assembly for a downlight according to an embodiment of the present invention, illustrating the open bottom of the reflector and the assembly partially disassembled;





FIG. 2

is a side elevational view of the reflector illustrated in

FIG. 1

, showing an outer prismatic surface of the reflector;





FIG. 3

is a top plan view of the reflector illustrated in

FIG. 1

, showing a textured inner surface and the outer prismatic surface of the reflector;





FIG. 4

is a side elevational view in cross-section of the reflector taken along


4





4


of

FIG. 3

, showing the textured diffusing inner surface of the reflector; and





FIG. 5

is a partial cross sectional view of the downlight and reflector according to the present invention, showing the downlight mounted to a ballast unit and a ceiling.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




Referring to

FIGS. 1-5

, a lighting fixture, or downlight,


10


according to the present invention includes a surface of revolution reflector


12


, a light source or lamp


14


disposed within the reflector


12


, and a mounting assembly


16


for securing downlight


10


to a ballast unit


18


and junction box


20


that are in turn mounted to a mounting surface


22


, such as a ceiling, as best seen in FIG.


5


.




Reflector


12


is a surface of revolution type of reflector having a central longitudinal axis of revolution


60


, and a reflector wall


24


that has a substantially parabolic cross-sectional shape with an inner surface


26


and an outer surface


28


. Reflector wall


24


is preferably substantially bell-shaped and formed of a transparent material such as glass, allowing light to pass therethrough. Since reflector


12


is transparent, inner and outer surfaces


26


and


28


are visible from either the inside or the outside of reflector


12


, as seen in

FIGS. 1-5

. Reflector wall


24


further includes a first or top end


30


and an opposing second or bottom end


32


. A first or top substantially circular opening


34


is disposed in top end


30


and second or bottom substantially circular opening


36


is disposed in bottom end


32


, with the diameter of bottom opening


36


being substantially larger than the diameter of top opening


34


.




Reflector wall


24


further includes integral top and bottom annular flanges


38


and


40


that facilitate securement of reflector


12


to mounting assembly


16


. Specifically, top flange


38


is disposed at top end


30


and extending upwardly therefrom, and defines the periphery of top opening


34


. Similarly, bottom flange


40


is disposed at bottom end


32


and extending outwardly therefrom and defines the periphery of bottom opening


36


. Top flange


38


has a planar upper surface


42


, a curved annular outer surface


44


, and a curved annular inner surface


46


so that outer surface


44


forms a substantially obtuse angle with outer surface


28


of reflector wall


24


, as best seen in FIG.


5


. Bottom flange


40


has planar upper and lower surfaces


48


and


52


and a curved annular outer surface


50


, so that upper surface


48


forms a substantially ninety degree angle with outer surface


28


of reflector wall


24


.




Inner surface


26


of reflector wall


24


is concave in shape and comprises first and second portions


54


and


56


. First portion


54


is located adjacent top end


30


and remote from bottom end


32


, and second portion


56


is located adjacent bottom end


32


and remote from top end


30


. Second portion


56


is substantially larger than first portion


54


such that second portion


56


is approximately two-thirds of inner surface


26


and first portion


54


is about one-third.




The majority of or the entire inner surface of first portion


54


is textured to create a substantially frustoconical diffusion surface


58


that re-directs the light rays from lamp


14


in various directions away from the axis of revolution


60


of reflector


12


that would otherwise be directed parallel to the axis of revolution


60


and cause hot spots. Textured surface can be formed in any known manner including but not limited to sand blasting, acid etching, or peening. Second portion


56


of inner surface


26


is substantially or entirely smooth allowing light rays from lamp


14


to pass therethrough to outer surface


28


. It is preferable that textured surface


58


be limited to first portion


54


of inner surface


26


and that the remaining second portion


56


be smooth to allow a greater portion of light rays to pass through reflector


12


. However, the extent of the textured surface


58


along inner surface


26


can vary depending on the degree of uniformity or smoothness required on the illuminated surfaces receiving light from lamp


14


.




The outer convex surface


28


reflects the light rays that pass through both first and second portions


54


and


56


of inner surface


26


. Specifically, outer surface


28


includes a plurality of curvilinear prisms


64


that extend along outer surface


28


between top and bottom flanges


38


and


40


of reflector wall


24


. Specifically, each prism


64


has first or top portion


66


that abuts the curved outer surface


44


of top flange


38


, and a second or bottom portion


68


that abuts the planar upper surface


48


of bottom flange


40


. As best seen in

FIG. 3

, each prism has a substantially isosceles triangular cross section. The angle at the apex of the triangle is preferably about 90 degrees, varying between 87 to 93 degrees. In addition, each prism


64


tapers in width from its bottom portions


68


to its top portion


66


. As the prisms taper the angle of the apex of each prism


64


remains constant as each prism


64


becomes more and more shallow with respect to outer surface


28


. Also, the number and width of prisms


64


can varying as desired, as long as outer surface


28


reflects lights rays coming through reflector wall


24


.




The majority of the light rays from lamp


14


are reflected by prisms


64


back into reflector


12


and downwardly through bottom opening


36


by the principle of total internal reflection. First portion


54


of inner surface


26


is a particular problem area in causing hot spots in surface of revolution style reflectors because of its proximity to lamp


14


. Specifically, more light rays are reflected downwardly by the outer prismatic surface parallel to axis


60


, than at a lower portion of the reflector, which spaced further from lamp


14


. By texturing the surface of first portion


54


(textured surface


58


), the light rays coming from lamp


14


are scattered away from axis of revolution


60


in a substantially conical shape around axis


60


to prevent the light from being directed downwardly and creating a hot spot. In addition, because first portion


54


is textured, varying the location of the lamp


14


with respect to first portion


54


will not create additional hot spots or voids that would disrupt the even illumination. Therefore, precise location of lamp


14


is not required and sensitivity to lamp position and manufacturing tolerances are minimized.




As seen in

FIG. 5

, mounting assembly


16


includes mounting plates


70


and


72


that mount to the ballast unit


18


, and a wire frame form


74


that supports reflector


12


. Each of first and second mounting plates


70


and


72


includes first and second support members or struts


76


and


78


, respectively, attached thereto proximate the bottom portions


80


of mounting plates


70


and


72


, preferably by welding. Each strut includes attached top and bottom L-shaped wire form members and have free end stems


82


extending outwardly, as best seen in FIG.


5


. The top portions


84


of first and second mounting plates


70


and


72


each have pivotal C-brackets


86


attached thereto for connection to ballast unit


18


. A first or top wire support ring


88


is attached to the outside of struts


76


and


78


, preferably by welding, to provide additional reinforcement to mounting assembly


16


.




Wire frame form


74


includes first and second wire frames


90


and


92


, each having top and bottom portions


94


and


96


. Top portions


94


each have a hook


98


for hooking to loops in struts


76


and


78


, respectively, and hooking over and under top wire support ring


88


, as best seen in FIG.


1


. Bottom portions


96


each include an angled loop


99


for attachment to an extending arm support


100


. A fastener


102


is employed for adjusting and tightening each of wire frames


90


and


92


with respect to arms


100


. Each arm support


100


comprises a unitary one piece member bent to form a first outwardly extending loop portion


104


with parallel legs forming a second downwardly extending portion


106


, and a third inwardly extending portion


108


forming a substantially S-shape, as best seen in

FIGS. 1 and 5

. An internally threaded nut member


107


is preferably attached to first loop portion


104


of each arm


100


for engaging loop


99


of each wire frame


90


and


92


and receiving fastener


102


. A second or bottom wire support ring


110


is attached to arm supports


100


at second portion


106


, preferably by welding, to provide rigidity to wire frame form


74


. A third wire support ring


112


is attached to the bottom of third portion


108


of arms


100


to also provide support and rigidity to wire frame form


74


and support for reflector


12


. Wire frame form


74


can alternatively include a third wire frame similar to wire frames


90


and


92


, and that also includes an arm support


115


, as seen in FIG.


1


.




To assemble downlight


10


, reflector


12


is first placed within wire frame form


74


. A bottom gasket


114


can be alternatively placed over third wire ring


112


on third portion


108


of arms


100


and bottom flange


40


of reflector


12


would be placed over gasket


114


so that the lower surface


52


of bottom flange


40


abuts gasket


114


, as best seen in FIGS.


5


. Gasket


114


provides cushioning between reflector


12


and third wire ring


112


. Without gasket


114


, bottom flange


40


rests directly on third wire ring


112


. With reflector


12


resting on arm supports


100


, wire frames


90


and


92


are disposed outside of reflector wall


24


for attachment to mounting plates


70


and


72


.




Mounting plates


70


and


72


with struts


76


and


78


are placed within top opening


34


of reflector wall


24


until stems


82


of each strut


76


and


78


abut upper surface


42


of top flange


38


. A top gasket


116


can be placed between top flange


38


and stems


82


of support struts


76


and


78


for cushioning, as best seen in

FIG. 5. A

wire ring


118


can alternatively be attached to the bottoms of struts


76


and


78


for proper centering of mounting plates


70


and


72


when placed within top opening


34


of reflector


12


.




Wire frames


90


and


92


can then be releasably attached to first and second struts


76


and


78


. Specifically, hooks


98


of each wire frame


90


and


92


are hooked onto struts


76


and


78


and top wire ring


88


. The resilient and flexible nature of wire frames


90


and


92


allows the wire frames


90


and


92


to stretch slightly so that they can be attached to arm supports


100


of each wire frame, as best seen in

FIGS. 1 and 5

. In particular, fasteners


102


are inserted through loops


99


of each wire frame


90


and


92


and then tightened with respect to nut


107


securing reflector


12


.




Downlight


10


can alternatively include a glass safety lens


120


pivotally attached to one of the arms


100


by a hinge assembly


122


, as best seen in FIG.


5


. Lens


120


acts to catch any broken glass that may result from an explosion of lamp


14


which could possibly occur, more likely with certain metal halide HID lamps, occurs after long extended use of the downlight without any shutdown in the operation. In addition, downlight


10


can include an auxiliary or backup lamp socket


124


.




Once assembled, downlight


10


can be mounted to ballast unit


18


. Ballast unit


18


includes a ballast housing


126


that holds the electrical components necessary for operation of downlight


10


, an electrically connected socket member


128


for receiving lamp


14


, and a mounting frame


130


for supporting downlight


10


via mounting assembly


16


. In particular, mounting plates


70


and


72


are coupled to mounting frame


130


of the ballast unit


18


by hooking C-brackets


86


to first and second tabs


132


extending from mounting frame


130


. Fasteners


134


are employed to securely attach C-brackets


86


to mounting frame


130


.




Once mounted, downlight


10


can be easily detached by removing fasteners


134


and unhooking C-brackets


86


. Ballast unit


18


is in turn connected to a junction box


20


which is mounted to mounting surface


22


by any known attachment, such as a rigid conduit


136


or bolts into structural member.




In use, lamp


14


, as seen in

FIG. 5

, is energized and creates illumination that extends radially outward of the lamp and axially downwardly therefrom. The illumination that extends downwardly from the lamp substantially follows the central axis


60


of revolution of the reflector, which substantially coincides with the central longitudinal axis of the lamp, and escapes through the reflector's bottom opening


36


.




The illumination, or light, escaping from the lamp and extending radially outwardly therefrom will be intercepted by and incident on the reflector wall, so that the majority of light is reflected back inside the reflector and downwardly, and the remaining light is transmitted outwardly.




In the textured portion at the top of the reflector, some of the light will be scattered inwardly by the textured inner surface, and some of the light will pass through the textured surface and then be reflected downwardly and transmitted upwardly by the prisms on the outer surface adjacent the textured portion. Below the textured portion, some of the light will be reflected by the smooth inner surface, and some of the light will pass through the smooth inner surface and then in turn be reflected back inwardly and downwardly adjacent the smooth portion. A small portion of light will be transmitted outwardly by the prisms adjacent the smooth portion. Therefore, the light emanating from the lamp will be evenly distributed without hot spots and voids.




The relative location of lamp


14


with respect to reflector


12


has several characteristics. Specifically, once connected to-socket member


128


, lamp


14


extends downwardly between mounting plates


70


and


72


and into top opening


34


of reflector


12


such that the bottom end of lamp


14


is substantially spaced form bottom opening


36


of reflector


12


, as best seen in FIG.


5


. Given the parabolic-shaped cross section of reflector


12


, first portion


54


of inner surface


26


is closet to lamp


14


both horizontally and axially, and second portion


56


near bottom opening


36


is furthest from lamp


14


. Thus, first portion


54


is textured at textured surface


58


due to its close proximity to lamp


14


because the light rays reflected downwardly, as described above, by inner surface


26


at first portion


54


will be closet to and directed along axis of revolution


60


thereby contributing the most to the problem of hot spots. Textured surface


58


scatters the light rays in directions other than parallel to axis


60


thereby avoiding hot spots




Moreover, the light rays reflected downwardly by inner surface


26


at second portion


56


will be horizontally spaced from axis of revolution thereby providing proper illumination and not contributing to hot spots generated proximate axis


60


. Therefore, smooth surface


62


, does not need to be textured. Thus the combination of textured surface


58


and smooth surface


62


of inner surface


26


of reflector


12


, creates an overall even illumination.




While a particular embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.



Claims
  • 1. A reflector for a lighting fixture having a light source, comprising:a reflector wall including, opposing first and second ends, said first end having a first opening disposed therein, and said second end having a second opening disposed therein, said second opening being substantially larger than said first opening, an inner surface, said inner surface including, a first portion being located adjacent said first opening and remote from said second opening, and having a non-prismatic textured diffusing surface for diffusing light rays from the light source, and a second portion being located adjacent said second opening and remote from said first opening with said second portion being substantially larger than said first portion, and having a smooth surface, and an outer surface having a plurality of curvilinear prisms thereon extending between said first and second ends for reflecting light rays from the light source.
  • 2. A reflector according to claim 1, wherein said non-prismatic textured diffusing surface entirely covers said first portion; and said smooth surface entirely covers said second portion.
  • 3. A reflector according to claim 1, whereinsaid reflector wall is formed of glass.
  • 4. A reflector according to claim 1, whereinsaid plurality of prisms entirely cover said outer surface of said reflector wall.
  • 5. A reflector according to claim 1, whereineach of said plurality of curvilinear prisms tapers from said second opening to said first opening.
  • 6. A reflector according to claim 1, whereinsaid first and second ends are top and bottom ends, respectively, and a mounting assembly is disposed on said top end for mounting said reflector to a ballast unit.
  • 7. A reflector according to claim 6, whereina wire frame is releasably secured to said reflector wall at said top and said bottom end for securing said reflector.
  • 8. A reflector according to claim 7, whereina lens is releasably secured to said bottom end of said reflector.
  • 9. A reflector according to claim 1, whereinsaid reflector wall is substantially parabolic in cross-section.
  • 10. A reflector according to claim 1, wherein said non-prismatic textured diffusing surface includes at least one of plurality of sand grains, an acid etching, and a plurality of peens.
  • 11. A lighting fixture assembly, comprising:a reflector including a reflector wall having opposing first and second ends, said first end having a first opening disposed therein, and said second end having a second opening disposed therein, said second opening being substantially larger than said first opening, an inner surface with a first portion being located adjacent said first opening and remote from said second opening, said first portion having a non-prismatic textured diffusing area, and a second portion being located adjacent said second opening and remote from said first opening with said second portion being substantially larger than said first portion, said second portion being smooth, and an outer surface having a plurality of curvilinear prisms thereon extending between said first and second openings; and a light source disposed within said reflector such that said non-prismatic textured diffusing area of said inner surface diffuses lights rays from said light source in multiple directions, and said outer surface reflects said light rays.
  • 12. A light fixture assembly according to claim 11, wherein said non-prismatic textured diffusing area entirely covers said first portion; said smooth surface entirely covers said second portion; and said plurality of prisms entirely cover said outer surface.
  • 13. A light fixture assembly according to claim 11, whereinsaid reflector wall has a substantially parabolic shape in cross-section forming an inner area between said first and second openings; and said light source is received within said inner area proximate said first end.
  • 14. A light fixture assembly according to claim 13, whereina mounting assembly is disposed on said first end of said reflector wall for mounting said reflector and said light source to a ballast unit.
  • 15. A light fixture assembly according to claim 13, whereina wire frame is releasably secured to said reflector at said first and second ends of said reflector wall securing said reflector to said mounting assembly.
  • 16. A light fixture assembly according to claim 11, wherein said non-prismatic textured diffusing area is defined by at least one of a plurality of sand grains, an acid etching, and a plurality of peens.
  • 17. A light fixture assembly according to claim 11, whereinsaid reflector is formed of glass.
  • 18. A light fixture assembly according to claim 11, whereina lens is releasably attached to said second end of said reflector wall.
US Referenced Citations (15)
Number Name Date Kind
821307 Mygatt May 1906 A
1413315 Correll Apr 1922 A
1543606 Harrison Jun 1925 A
1891846 Stauber, Jr. Dec 1932 A
2132784 Guth Oct 1938 A
3466437 Ruehl Sep 1969 A
3800138 Shadwick Mar 1974 A
3825742 Levin Jul 1974 A
4285034 Sullivan Aug 1981 A
4611266 Schwartz Sep 1986 A
4839781 Barnes Jun 1989 A
4987524 Miller Jan 1991 A
5121309 Ewing et al. Jun 1992 A
5444606 Barnes et al. Aug 1995 A
5957565 Hofmann Sep 1999 A