U.S. patent number 3,705,303 [Application Number 05/123,553] was granted by the patent office on 1972-12-05 for luminaire.
This patent grant is currently assigned to General Electric Company. Invention is credited to John R. Judge, Candler A. Willis, Jr..
United States Patent |
3,705,303 |
Willis, Jr. , et
al. |
December 5, 1972 |
LUMINAIRE
Abstract
Luminaire for indoor industrial use has an optical assembly
having a diameter substantially greater than its height and adapted
to be mounted at a relatively low height above the floor. The
optical assembly comprises a reflector with fluted concave upper
portion and an outwardly flaring lower skirt portion to which a
large diameter dish-shaped refractor is secured. The refractor has
an annular side wall formed with horizontal rows of prisms which
depress part of the incident light and reflect the remaining light
rays upwardly toward the ceiling. The bottom panel of the refractor
is formed with radial light dispersing flutes.
Inventors: |
Willis, Jr.; Candler A.
(Zirconia, NC), Judge; John R. (Mobile, AL) |
Assignee: |
General Electric Company
(N/A)
|
Family
ID: |
22409345 |
Appl.
No.: |
05/123,553 |
Filed: |
March 12, 1971 |
Current U.S.
Class: |
362/308; 362/327;
362/328; 362/329; 362/333; 362/337 |
Current CPC
Class: |
F21V
13/04 (20130101); F21S 8/06 (20130101) |
Current International
Class: |
F21S
8/04 (20060101); F21V 13/00 (20060101); F21V
13/04 (20060101); F21S 8/06 (20060101); F21v
013/04 () |
Field of
Search: |
;240/25,92,93,13R,13B,16R,106.1,149 ;D48/23 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Uddeholm-Lighting Masts Specification, 1965, page 22, section
200.
|
Primary Examiner: Matthews; Samuel S.
Assistant Examiner: Adams, Jr.; Russell E.
Claims
What we claim as new and desired to secure by Letters Patent of the
United States is:
1. A luminaire comprising, in combination, an optical assembly
comprising a reflector having an upper portion and a lower
downwardly flaring skirt portion defining an open bottom, and a
generally dish-shaped refractor having an open top and a closed
bottom, said reflector and said refractor being connected to each
other at their peripheries with said refractor arranged below and
closing the bottom of said reflector, said optical assembly being
substantially greater in overall diameter than in height, and a
lamp mounted in said optical assembly and having a light center
arranged above the bottom of said reflector, said refractor having
a peripheral side wall formed on its outer surface with annular
rows of prisms having substantially vertical refracting surfaces
and substantially horizontal reflecting surfaces, said
substantially vertical refracting surfaces depressing light rays
incident thereon from said lamp downwardly from said optical
assembly, and said substantially horizontal reflecting surfaces
re-directing light rays incident thereon from said lamp upwardly
from said optical assembly.
2. A luminaire as defined in claim 1, said refractor having a
bottom panel formed with a plurality of elongated refracting
portions radiating from the center of said bottom panel for
circumferentially spreading light rays emanating from said
panel.
3. A luminaire as defined in claim 2, said elongated radiating
refracting portions comprising transversely convex flutes formed on
the inner surface of said refractor panel.
4. A luminaire as defined in claim 3, said flutes being of
substantially constant refractive power along their lengths.
5. A luminaire as defined in claim 1, a ballast housing arranged
above and connected to said optical assembly for supporting the
same, and an accessory reflector mounted at the bottom of said
ballast housing above said upper reflector portion for reflecting
light rays from said lamp downwardly through said refractor.
6. A luminaire as defined in claim 1, said reflector portions being
formed with flutes for horizontally spreading light rays from said
lamp.
7. A luminaire as defined in claim 1, the height of said reflector
being about twice the height of said refractor.
8. A luminaire as defined in claim 7, the overall diameter of said
optical assembly being at least twice its height.
Description
The present invention relates to lighting fixtures, and
particularly to luminaires of industrial indoor type.
It an object of the invention to provide a luminaire of the above
type which spreads light over a large floor area when mounted at a
relatively low height.
Another object of the invention is to provide a luminaire of the
above type wherein the luminaire brightness or glare is minimized,
especially in the zone between vertical angles of between about
45.degree. to 90.degree.. By "vertical angles" is meant the angle
up from nadir defined by a light ray relative to the vertical axis
of the light source.
Still another object of the invention is to provide a luminaire of
the above type from which a portion of the light is directed toward
the ceiling to minimize contrast.
A further object of the invention is to provide a luminaire of the
above type which has a relatively low overall profile.
Other objects and advantages will become apparent from the
following description and the appended claims.
With the above objects in view, the present invention in one of its
aspects relates to a luminaire comprising, in combination, an
optical assembly comprising a reflector having an upper portion and
a lower downwardly flaring skirt portion defining an open bottom,
and a generally dish-shaped refractor having an open top and a
closed bottom, the reflector and refractor being connected to each
other at their peripheries with the refractor arranged below and
enclosing the bottom of the reflector, the optical assembly being
substantially greater in overall diameter than in height, and a
lamp mounted in the optical assembly, the refractor having a
peripheral side wall formed with prisms for depressing light rays
from the lamp downwardly toward the area to be illuminated by the
luminaire.
The invention will be better understood from the following
description taken in conjunction with the accompanying drawings in
which:
FIG. 1 is a view in elevation, partly broken away, of an industrial
luminaire embodying the invention;
FIG. 2 is a top plan view of the refractor employed in the optical
assembly of the FIG. 1 luminaire;
FIG. 3 is a bottom plan view of the main luminaire reflector of the
optical assembly;
FIG. 4 shows a segment of the luminaire reflector as viewed along
the line 4--4 in FIG. 1;
FIG. 5 is a somewhat schematic view of a vertical section of a
portion of the luminaire optical assembly showing the path of light
rays therein;
FIG. 6 is a view in vertical section of a portion of the refractor
taken along the lines 6--6 in FIG. 2;
FIG. 7 is an enlarged detail view of the side wall prisms of the
refractor; and
FIG. 8 is an enlarged cross-sectional view of a portion of the
bottom panel of the refractor taken along the lines 8--8 of FIG.
6.
Referring now to the drawings, and particularly to FIG. 1, there is
shown an industrial luminaire comprising a somewhat dome-shaped
ballast housing 1 connected to and supported by a wire conduit 2,
such as a metal pipe, and containing electrical operating
components such as ballast transformer 3 and capacitor 4. Ballast
housing 1 is formed with cooling fins 1a for radiating and
dissipating heat generated therein by the electrical operating
components. Suspended from ballast housing 1 below the open bottom
thereof is optical assembly 5 comprising reflector 6 and refractor
7.
Reflector 6 is formed of a somewhat conical upper portion 6a open
at its top and a lower outwardly flaring skirt portion 6b, with
both reflector portions having reflecting flutes formed in the
walls thereof, as seen in FIG. 3 wherein such flutes are shown only
in one sector for the sake of simplicity. Refractor 7 is a shallow,
somewhat dish-shaped transparent member having light control prisms
7a extending around the outer surface of its peripheral wall. In
the optical assembly, as seen in FIG. 1, the lower rim of reflector
skirt portion 6b mates with the upper flanged rim of refractor 7,
and they are securely joined together in permanent sealed relation
by suitable means, such as by forming the reflector rim into an
annular channel 6c in which the annular flanged rim of refractor 7
is received and held.
Lamp 8 is arranged in optical assembly 5 with its base down and
mounted in that position by bracket 10. Bracket 10 is generally
V-shaped and secured at its upper arms to opposite upper portions
of reflector 6. The apex of bracket 10 at its bottom is formed with
a seat 10a in which lamp socket 9 with support bracket 9a is
received and suitably secured. In such arrangement, lamp socket 9
is located closely adjacent the inner surface of the bottom panel
of refractor 7, and lamp 8 extends upwardly in the optical
assembly. The light center LC of lamp 8 is thus arranged in the
proper position as shown in FIG. 1 relative to reflector 6 and
refractor 7 to provide the desired light distribution.
Optical assembly 5 is detachably connected to ballast housing 1 by
means of hinge 11 and latch 14 so as to permit the optical assembly
to be swung down from ballast housing 1, thus providing access to
the interior of the optical assembly. A separable electrical
connection between the detachable parts is provided by electrical
plug 16 secured to reflector 6 and electrical receptacle 17 secured
to ballast housing 1 as shown in FIG. 1. These and other mechanical
features are more fully disclosed in co-pending application of
Judge et al, Ser. No. 123,685, filed Mar. 12, 1971, and assigned to
the same assignee as the present invention.
In a typical luminaire constructed in accordance with the
invention, the overall diameter of optical assembly 5 at the
junction of reflector 6 and refractor 7 is about 31 inches, the
overall height of the unit including ballast housing 1 and optical
assembly 5 is about 21 inches, and the height of the optical
assembly 5 is about 12 inches with the height of refractor 7 being
only about 4 inches. Thus, the overall diameter of the optical
assembly is substantially greater than the overall height of the
entire unit and more than twice the height of the optical assembly.
Because of the relatively large size of the refractor used in such
a luminaire, it would usually be made of a synthetic plastic
material such as an acrylic resin. Such a material is subject to
discoloration if exposed to excessive heat due to close proximity
to the lamp. By arranging lamp 8 with its base down, adequate
spacing is provided between refractor 6 and the relatively hotter
bulb portion of lamp 8 while still utilizing the space adjacent
refractor 6 for the cooler lamp base and socket member 9. A further
advantage in this arrangement is that the height of the ballast
housing can be reduced since it need not accommodate the lamp
socket, which in a base-up arrangement would have to be placed
within the ballast housing so that the light center of lamp 8 can
be correctly located at the proper optical position relative to the
reflector flutes 6d and the refractor prisms 7a, as more fully
disclosed herein. Such proper positioning of the light center of
lamp 8 is necessary to provide the desired distribution of light on
the floor to be lighted as well as to avoid undue glare from the
luminaire. In addition, the relatively low profile of the luminaire
thus achieved makes it feasible to use the luminaire in areas
having relatively low ceilings.
As seen in the embodiment illustrated in FIG. 1, lamp 8 is arranged
so that its light center LC is arranged somewhat above the bottom
of upper reflector portion 6a. The latter reflector portion is
relatively steeper in slope than reflector skirt portion 6b, and
whereas the interior surface of reflector portion 6a is generally
concave, reflector skirt portion 6b is straight in vertical
section. As a result, as seen in FIG. 5, light rays from the light
center LC of lamp 8 which are incident on upper portion 6a are
reflected downwardly therefrom toward the opposite side of the
luminaire, while light rays striking skirt portion 6b are reflected
downwardly and outwardly therefrom toward the same side of the
luminaire.
As seen in the generally horizontal section of reflector portion 6a
shown in FIG. 4, flutes 6d have transversely convex inner
reflecting surfaces so as to spread incident light rays in
horizontal (i.e., lateral) directions. Similar flutes formed in
skirt portion 6b similarly horizontally spread the light rays
incident thereon.
Arranged at the open bottom of ballast housing 1 above the top
opening of main reflector 6 (see FIG. 1) is accessory reflector 19
secured at its central portion to housing 1 by suitable means. As
shown in FIG. 5, reflector 19 has a downwardly dished central
portion 19a, a flat annular intermediate portion 19b extending
substantially horizontally, and a downwardly sloping outer rim
portion 19c. The light rays from lamp 8 striking central portion
19a are deflected therefrom downwardly and outwardly away from the
lamp axis, intermediate portion 19b reflects light rays downwardly
at smaller vertical angles than those reflected from portion 19a,
and reflector rim portion 19c reflects light rays back toward the
opposite side of the luminaire. Reflector rim portion 19c is
preferably formed with flutes on its reflecting surface similar to
those of main reflector 6 as shown in FIG. 4 to horizontally spread
the incident light rays. In general, the light rays reflected from
accessory reflector 19 as well as those reflected from main
reflector portion 6a are directed downwardly through the bottom
panel 7b of refractor 7. As seen in the plan view of FIG. 2, bottom
panel 7b is formed on its inner surface with radially extending
flutes 7e or the like, which serve (see FIG. 8) to disperse the
light rays emanating therefrom so as to spread them over the area
to be illuminated below the luminaire. Flutes 7e are transversely
convex but are of substantially constant refractive power along
their lengths, so that the emanating light rays are fanned out in
varying vertical angles in circumferential direction without an
appreciable change in vertical angle in radial directions as
between a particular incident light ray and a corresponding
emanating light ray.
As seen in FIG. 5, the light rays from lamp 8 which are reflected
from reflector skirt portion 6b are incident on the prismatic side
wall 7a of refractor 7, and a portion of direct light rays from
lamp 8 are also incident thereon. Side wall 7a is formed on its
outer surface with annular parallel rows of horizontal prisms, the
rows from top to bottom being of decreasing diameter so as to be
offset inwardly from one another as shown. Each prism (see FIG. 7)
has a substantially horizontal reflecting surface 7c and a
substantially vertical refracting surface 7d. By virtue of this
structure and the arrangements described above, light rays incident
on refractor wall 7a are in part refracted and depressed by
vertical wall 7d of the prisms and in part are reflected by
horizontal face 7c of the prisms so as to be directed upwardly and
outwardly from the luminaire. As a result of this double-acting
function of prisms 7a, a portion of the light is directed toward
the ceiling to minimize contrast between the illumination of the
floor and the ceiling, light rays are spread over a wide floor area
even when the luminaire is mounted at a relatively low height, and
the brightness (glare) from the luminaire in the zone of about
45.degree. to 90.degree. vertical angles is considerably reduced.
Excessive brightness is also minimized due to the relatively large
area of light emission from the large size refractor.
While the present invention has been described with reference to
particular embodiments thereof, it will be understood that numerous
modifications may be made by those skilled in the art without
actually departing from the scope of the invention. Therefore, the
appended claims are intended to cover all such equivalent
variations as come within the true spirit and scope of the
invention.
* * * * *