Illumination – Light modifier – Reflector
Reexamination Certificate
1999-04-14
2003-09-16
Sember, Thomas M. (Department: 2875)
Illumination
Light modifier
Reflector
C362S297000, C362S296040, C362S341000, C362S347000, C362S348000, C362S346000
Reexamination Certificate
active
06619821
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to lighting systems and, more specifically, to parabolic reflectors. Still more specifically, the present invention relates to a parabolic reflector capable of delivering an asymmetrical light distribution.
BACKGROUND OF THE INVENTION
Light fixtures that include reflectors, such as parabolic reflectors, have numerous applications. One typical application for a parabolic reflector is a light fixture that hangs from a ceiling for lighting a narrow walkway or hallway disposed between two walls or two banks of shelves, such as an in a warehouse or in a storage facility. An example of such an application is illustrated schematically in FIG.
1
. Specifically, a light fixture
10
is shown hanging between two shelving units
11
,
12
. The area
13
to be lit is relatively narrow. Because a typical light fixture
10
will provide a circular light distribution (not shown), a number of light fixtures
10
must be strung along the walkway or area
13
to be lit.
A circular light distribution for the arrangement shown in
FIG. 1
is inefficient because it is desirable to direct the light downward to cover as much of the area
13
as possible without wasting light on the top surfaces
14
,
15
of the shelving units
11
,
12
respectively or along the upper portions
16
,
17
of the shelving units
11
,
12
respectively. For efficiency, the light must be directed downward toward the floor or walkway.
Therefore, a conventional circular light distribution (not shown) for the light fixture
10
would be inefficient. Large amounts of the light distribution would be wasted on the upper sides
16
,
17
and top surfaces
14
,
15
of the shelving units
11
,
12
. Further, a circular light distribution would not provide an effective distribution of light in the direction of the arrows
18
,
19
or along the narrow area
13
that needs to be lit.
As a result, light manufacturers have developed light fixtures that provide an elliptical light distribution. However, conventional methods for converting a parabolic light reflector so that it produces an elliptical or asymmetrical light distribution as opposed to a circular or symmetrical light distribution reduces the efficiency of the fixture. Specifically, the typical means for producing an elliptical distribution from a parabolic light reflector includes the use of an insert or refractor inside the reflector. The inserts and refractors, in addition to being costly, reduce the efficiency of the light fixture or luminaire. As a result, while an elliptical light distribution is achieved, less light is distributed and the overall efficiency is reduced as a result.
Accordingly, there is a need for a conventional parabolic reflector that efficiency produces an elliptical light distribution for lighting narrow hallways and walkways such as those illustrated in FIG.
1
.
SUMMARY OF THE INVENTION
The present invention satisfies the aforenoted need by providing a light fixture that comprises a parabolic reflector which, in turn, comprises an inside surface. The inside surface of the reflector comprises four quadrants including two coated quadrants disposed between two uncoated quadrants.
In an embodiment, the reflector is fabricated from aluminum so that the uncoated quadrant provide an aluminum surface for the reflection of light.
In an embodiment, the coated quadrants are coated with a white paint.
In an embodiment, the coated quadrants are coated with a white powdered coating.
It has been found that by aligning the coated quadrants on opposing sides of a center line that extends longitudinally through the narrow area to be coated, an elliptical light distribution is achieved without substantially reducing the efficiency of the reflector.
In other words, the amount of light distributed by a parabolic reflector coated as described above is substantially the same amount as the light reflected by a completely uncoated or metallic parabolic reflector.
The coating of opposing quadrants in accordance with the present invention is more economical than conventional parabolic reflectors that provide an elliptical light distribution. Specifically, typical reflectors provide an elliptical or asymmetric distribution utilize a refractor or an insert which, both add to the cost of the reflector or the luminaire, and which also reduce the efficiency of the luminaire. Painting of opposing quadrants with a highly reflective paint, such as a white paint, or white powdered coating is cheaper than the use of refractors or inserts and further achieves the asymmetric or elliptical light distribution without sacrificing overall optical efficiency.
The two uncoated or specular quadrants will distribute light in accordance with the normal distribution pattern of the reflector. Accordingly, the two uncoated or specular quadrants should be aligned with the center line of the aisle or passageway to be lit. The painted quadrants should be disposed on opposing sides of the center line or longitudinal axis of the aisle or passageway to be lit. The painted quadrants will disperse the light along the hallway to provide an asymmetrical light distribution which will also soften the lumen intensity thereby reducing glare.
In an embodiment, the present invention provides a method for manufacturing a reflector for providing asymmetrical light distribution which includes the steps of providing a metallic parabolic reflector comprising an inside surface, and coating two opposing quadrants of the inside surface with a white coating so that the inside surface is characterized as having four quadrants including two coated quadrants disposed between two uncoated quadrants.
In an embodiment, the coating step further comprises coating the opposing quadrants with a white powdered coating.
It is therefore an advantage of the present invention to provide a simple, economical and highly efficient means for providing an asymmetrical light distribution.
It is another advantage of the present invention to provide an effective means for converting a conventional parabolic reflector that would normally generate a circular light distribution to a reflector that generates an asymmetrical light distribution.
Other objects and advantages of the present invention will become apparent to those skilled in the art upon reviewing the following detailed description, drawings and appended claims.
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patent: 4066887 (1978-01-01), Levis
patent: 4207607 (1980-06-01), Gulliksen
patent: 4213171 (1980-07-01), Sassmannshausen
patent: 4229782 (1980-10-01), Ruud et al.
patent: 4231080 (1980-10-01), Compton
patent: 4428038 (1984-01-01), Rakitsch et al.
patent: 4630895 (1986-12-01), Abdala, Jr. et al.
patent: 5010458 (1991-04-01), Fraizer
patent: 5493483 (1996-02-01), Lake
patent: 5526248 (1996-06-01), Endo
patent: 6036338 (2000-03-01), Gordin
Genlyte Thomas Group LLC
Haeberlin Jeffery A.
Middleton & Reutlinger
Sember Thomas M.
Ton Anabel
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