U.S. patent number 3,651,320 [Application Number 05/042,385] was granted by the patent office on 1972-03-21 for lighting fixtures.
This patent grant is currently assigned to Moldcast Manufacturing Company. Invention is credited to Martin Lawrence Lasker.
United States Patent |
3,651,320 |
Lasker |
March 21, 1972 |
LIGHTING FIXTURES
Abstract
A lighting fixture employs a pair of reflectors related to a
lamp housing which includes socket means for a lamp. One reflector
is substantially tubular and extends into the housing to surround a
portion of a lamp. The second reflector having a diameter larger
than the diameter of the first reflector is positioned above in
spaced relationship with respect to the first reflector. An
enclosure of light transmitting material extends between the spaced
reflectors and has a diameter which is not less than the diameter
of the second reflector. The second reflector is formed to
distribute light directed thereto from a lamp and from the first
reflector through the enclosure. By selecting tubular reflectors
having differently angled inner reflecting surfaces, different
illumination patterns are obtained without changing the outer
dimensions of the tubular reflector or of the fixture.
Inventors: |
Lasker; Martin Lawrence
(Metuchen, NJ) |
Assignee: |
Moldcast Manufacturing Company
(Newark, NJ)
|
Family
ID: |
21921639 |
Appl.
No.: |
05/042,385 |
Filed: |
June 1, 1970 |
Current U.S.
Class: |
362/303;
362/375 |
Current CPC
Class: |
F21V
7/0033 (20130101); F21S 8/088 (20130101); F21V
7/0008 (20130101) |
Current International
Class: |
F21V
7/00 (20060101); F21S 8/08 (20060101); F21p
001/00 () |
Field of
Search: |
;240/25,13R,105,1.1,41.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Ruehl; Charles A.
Claims
I claim:
1. A lighting fixture comprising a lamp housing including socket
means for a lamp, a first substantially tubular reflector adapted
to surround a portion of a lamp, a second reflector having a
diameter larger than the diameter of the first reflector spaced
from and positioned above the first reflector, and an enclosure of
light transmitting material having a diameter not less than the
diameter of the second reflector extending between and connected to
the reflectors, the enclosure having a central opening on its
underside, an annular support member secured to the enclosure
extending through the opening, said first reflector being mounted
on the support member to extend therethrough and into the lamp
housing, the second reflector lying in a plane substantially
transverse of a central longitudinal axis extending through the
socket means, the first reflector and the second reflector, and
means separably connecting the support member to the lamp
housing.
2. A lighting fixture according to claim 1, wherein the first
reflector is substantially frustoconical and has its largest
internal diameter at the end thereof facing the second
reflector.
3. A lighting fixture according to claim 2, wherein the inner
reflecting surface of the first reflector is at a relatively wide
angle with respect to the central longitudinal axis.
4. A lighting fixture according to claim 2, wherein the inner
reflecting surface of the first reflector is at a relatively narrow
angle with respect to the central longitudinal axis.
5. A lighting fixture according to claim 2, wherein the inner
reflecting surface of the first reflector has a segment thereof at
a relatively wide angle and a segment at a relatively narrow angle
with respect to the central longitudinal axis.
6. A lighting fixture according to claim 1, wherein the second
reflector is circular and has an annular concave portion
intermediate its center and its outer periphery.
7. A lighting fixture according to claim 1, including means for
hinging the support member to the lamp housing.
8. A lighting fixture according to claim 1, wherein the enclosure
has a central opening on its upperside, the second reflector being
positioned in said opening, and means to secure said reflector to
the adjoining wall of the enclosure.
9. A lighting fixture according to claim 1 wherein the socket means
is mounted on a bracket having radially extending flanges,
resiliency mounted screw means extended through the flanges and
cooperable with a wall of the housing.
Description
The invention relates to lighting fixtures, and is more
particularly directed to improvements in outdoor lighting fixtures
of the type wherein the light source is hidden from the viewer.
BACKGROUND OF THE INVENTION
The glare zone of a lighting fixture is the wide angle most common
to viewers approaching the fixture. The illumination zone is the
area of desired illumination and may be varied in accordance with
the shape of the area to be illuminated. In a lighting fixture for
indoor or outdoor use, it is desirable to obtain light distribution
over a relatively wide illumination zone while retaining an
extremely low glare appearance. Such characteristics are of
particular concern in outdoor lighting arrangements where it is
desired that the fixture illuminate a relatively wide area together
with the elimination of glare. Glare causes interference with
normal viewing and, in general, detracts from the overall
appearance of both the fixture and of the area illuminated.
It also is desirable that a lighting fixture permit simple
modification of its structure to enable changing or altering the
distribution of light emitted thereby. There are various prior art
devices which contain movable parts in order to direct or redirect
light to cover selected areas. Such prior art devices include
swivel type bases and other mechanically movable means which are
subject to wear and generally require maintenance.
Other prior art lighting fixtures of the hidden light source type
are provided with various reflector arrangements whereby the light
is emitted to a constant predetermined area. While such devices
eliminate the mechanical means for altering the light pattern, any
change or modification which will furnish an enlarged area of
illumination or different light pattern is accompanied by the
requirement to change the size of the fixture and the associated
reflectors. As a result, the manufacturer or supplier must include
a relatively large inventory of various size fixtures to
accommodate different lighting requirements.
SUMMARY OF THE INVENTION
In accordance with the invention, a lighting fixture is provided
which comprises a lamp housing including socket means for a lamp. A
first substantially tubular reflector extends into the housing and
is adapted to surround a portion of a lamp. A second reflector
having a diameter larger than the diameter of the first reflector
is positioned above and spaced from the first reflector. An
enclosure of light transmitting material which has a diameter not
less than the diameter of the second reflector extends between and
is connected to the reflectors. The second reflector lies in a
plane substantially transverse of the central longitudinal axis
through the fixture; that is, the axis which extends through the
socket means, the first reflector and the center of the second
reflector. The second reflector acts to distribute light directed
thereto from a lamp and from the first reflector, the light being
emitted through the light transmitting enclosure.
Without changing the outer parameters of the reflector or lighting
fixture, different and enlarged illumination zones are obtained by
simply changing the angle of the reflecting surface provided by the
first or substantially tubular reflector which acts as a collecting
reflector and directs light to the constant second or distributing
reflector.
In the preferred form of the invention, the two reflectors and the
enclosure of light transmitting material are in the form of a
unitary assembly. The enclosure itself acts as the means for
maintaining the reflectors is predetermined spaced relationship.
The unitary assembly aspect of these essential parts enables the
disconnection of the assembly from a lamp housing for relamping
when necessary, while maintaining the predetermined fixed spatial
relationship of the parts of the assembly and the proper alignment
of the parts with the light source.
These, and other advantages and improved results of the invention
will be apparent from the following description of a preferred
embodiment of the invention, taken in conjunction with the drawings
which are on a reduced scale.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a lighting fixture made in
accordance with the invention, the fixture being shown atop a pole
which is partially illustrated;
FIG. 2 is a vertical, cross sectional view of a lighting fixture
shown in FIG. 1, this view also showing various line
representations of the patterns of the light rays:
FIG. 3 is a view taken approximately in the plane of line 3--3 of
FIG. 2;
FIG. 4 is a view taken approximately in the plane of line 4--4 of
FIG. 2;
FIG. 5 is a horizontal, cross sectional view taken approximately in
the plane of line 5--5 and in the indicated directions of FIG.
2;
FIG. 6 is a vertical cross sectional view similar to FIG. 2, this
partial view including a collecting reflector having a differently
angled reflecting surface than the collecting reflector shown in
FIG. 2;
FIG. 7 is a view similar to FIG. 2 except that the assembly of the
reflectors and the light transmitting enclosure is shown retracted
from the lamp housing about a hinge;
FIG. 8 is a partial perspective view of a pair of lighting fixtures
having an annular configuration rather than a square contour as
shown in FIG. 1, the fixtures being mounted atop a pole partially
shown; and
FIGS. 9, 10, 11 and 12 are schematic views illustrating a plurality
of illumination patterns which may be provided by a lighting
fixture made in accordance with the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings, and as best shown in FIG. 2, a lighting
fixture F made in accordance with the invention comprises a lamp
housing A which includes socket means 20 adapted to receive a lamp
L. A substantially tubular reflector B extends into the housing and
is adapted to surround the upper portion of the lamp. A second
reflector C having a diameter larger than the diameter of the
reflector B is positioned above and spaced therefrom. An enclosure
D made of a light transmitting material extends between and is
connected to the reflectors B and C. The enclosure has an overall
diameter not less than the diameter of the reflector C. The
reflector C lies in a plane substantially transverse of the central
longitudinal axis o (also the optical axis) of the fixture, or the
axis which extends centrally through the socket means 20 and the
centers of the reflectors B and C. The distributing reflector C
distributes light directed thereto from a lamp and from the
collecting reflector B, the light being emitted through the
enclosure D.
The described lighting fixture is particularly suitable for outdoor
lighting. As shown in FIG. 1, the fixture F is mounted atop a
hollow pole P within which suitable power lines (not shown) are
extended to the socket 20. As is known in the art, a ballast 22 may
be positioned within the pole to energize a light source, for
example, a mercury vapor lamp. Any suitable light source may be
fitted into the socket including an incandescent lamp.
In greater detail, the lamp housing A preferably is made by die
casting a suitable alloy such as aluminum or zinc, and is opaque.
The housing which is hollow and generally frustoconical in its
interior with the larger diameter at the top is formed at its lower
end with an opening to receive the top end of the pole P. A sealing
gasket 24 is provided between the wall of the pole and the
periphery of the opening. The socket 20 preferably is resiliently
mounted and together with resilient means for engaging the sides of
a lamp, furnishes a universal floating mounting for the lamp which
assures that the optical axis of the lamp is centered on the axis
o, and further accommodates lamps of varying length wherein the
bulb may also be slightly eccentric with respect to its base.
As shown in FIG. 2, the socket 20 is held in the housing by a
bracket 26, the bracket being provided with radially extending
flanges 28 through which screws 30 are extended with the ends of
their shanks bearing against a wall provided by the housing. The
shanks of the screws intermediate the bracket flanges and the heads
of the screws accommodate helically coiled compression springs 32.
As shown in FIGS. 2 and 5, a plurality of circumferentially
arranged shoulders 34 are provided to furnish supports for the
connection thereto of respective leaf spring members 36 adapted to
engage and centralize a lamp L when positioned within the
resiliently mounted socket 20. The described arrangement assures
that the grid or filament 38 of the lamp is located on the central
axis o.
As also shown in FIG. 2, an annular lower support member 40 having
a central opening substantially equal to the opening of the lamp
housing at its top side is positioned to rest upon the upper edge
of the housing. For convenience in manufacture, the member 40
preferably is made as a separate piece by die casting. Actually,
the member 40 functions as a part of the lamp housing. As best
shown in FIGS. 2 and 7, the member 40 is connected to the housing A
by a plurality of circumferentially arranged screws 42 which extend
through the member and into tapped holes formed in the lamp
housing. As shown in FIGS. 2 and 5, an upper support member 44
substantially identical with the member 40 rests thereon and is
releasably connected thereto and to the lamp housing by a plurality
of spaced, circumferentially arranged screws 46 extended through
the housing, through the lower support member 40 and into tapped
holes formed in the upper support member 44.
The support member 44 serves as a mounting for the collecting
reflector B. As shown in FIG. 2, this reflector is substantially
tubular and of inverted frustoconical form, it being flared
outwardly at the top. The reflector is provided with an annular
peripheral flange 48 permitting connection to the support member 44
by a pair of clips 50. As shown in FIG. 4, the clips are located to
engage the flange 48 on opposite sides of the reflector. The clips
are secured by screws 52 extended through the ends of the clips
with the shanks of the screws in tapped holes formed in the upper
support member 44. The reflector B preferably is made of aluminum
and is provided with an inner reflecting surface 54. Any suitable
reflecting surface may be provided, for example, a specular
anodized finish with a minimum 80 percent reflectance. The
reflecting surface 54 as presented toward the central axis o of the
fixture is convex.
The distributing reflector C is maintained in predetermined spaced
relationship above the reflector B by the intermediate connecting
enclosure D. The enclosure is made of a light transmitting
material, preferably a transparent material such as a clear acrylic
resin or glass which may be tinted. Although not as desirable, a
translucent material may be used. The enclosure has a wall
sufficiently thick to serve as a structural material whereby the
reflectors are maintained in predetermined spaced relationship by
the enclosure. As will be evident from FIG. 2, the reflector C has
a diameter substantially greater than the diameter of the reflector
B, and the light transmitting enclosure D has a diameter which is
at least as great, and preferably greater than the diameter of the
reflector C. For example, and not by way of limitation, the
reflector C may have a diameter of approximately 23 inches; the
reflector B a diameter of approximately 7.5 inches at the top where
it has its largest diameter (exclusive of the connecting flange);
and the light transmitting enclosure D may have a diameter of 26.5
inches. It will be understood that the term "diameter" is used in
the general sense to include the transverse dimension of a square
part since the enclosure, for example, may have a square FIG. 1
rather than a circular (FIG. 8) contour.
As will be subsequently described, the support member 44, the
collecting reflector B, the distributing reflector C, and the light
transmitting enclosure D preferably constitute a unitary
assembly.
As shown in FIGS. 2 and 3, the reflector C, which preferably is
made of aluminum, is circular and has an inner reflecting surface
55. Any suitable polished reflecting surface may be provided, for
example, a specular anodized finish with a minimum 80 percent
reflectance. The reflecting surface 55 faces the reflector B and a
lamp L when inserted in the socket 20. As shown in FIG. 2, the
reflector C lies in a plane substantially transverse of the central
longitudinal axis o, and in the preferred embodiment of the
invention as shown, the reflector is contoured to provide an
annular, rather shallow concave surface intermediate the center and
the outer periphery of the reflector.
As shown in FIGS. 2 and 7, the enclosure D is formed with a central
opening 56 on its bottom side 58. As shown in FIG. 5, the upper
support member 44 is provided with spaced, tapped holes 60 to
receive screws (not shown) which are extended through the bottom
wall of the enclosure just outwardly of the opening 56 to thereby
secure the enclosure to the support member. A sealing gasket 57 is
positioned in a groove formed on the top side of the member 40 for
engagement with the enclosure wall 58, and a second sealing gasket
59 is positioned in a groove formed on the underside of the support
member 44 for engagement with the opposite side of the enclosure
wall 58.
As shown in FIGS. 2 and 3, the enclosure D is secured to the
distributing reflector C by a dome-like connecting member 62,
preferably made of aluminum, and by a supporting bracket 64. The
bracket is connected at the top to the dome member 62 by threading
nuts onto connecting studs 66 after the flanges 68 of the bracket
are positioned on the studs. The lower end of the bracket is
provided with a tapped hole through which a screw 68 is extended,
the head of the screw being positioned on the inner side of the
reflector at its center. The top side 70 of the enclosure D is
provided with a large central opening 72 to allow the inturned edge
74 of the reflector C to extend therethrough with a close fit. The
dome member 62 has a downturned flange 76 to engage the wall 70 of
the enclosure. A gasket 78 is positioned between the parts to
provide a seal. The unitary assembly of the two reflectors and the
light transmitting enclosure is completed by securing the dome
member to the enclosure in any suitable manner. As shown in FIG. 3,
a plurality of connector clamps 80 may be utilized for this
purpose. The come member may be provided with tapped holes and the
clamp members may be held by screws extended into the tapped
holes.
To enable ready access to the inside of the lamp housing A for
lamping and relamping, hinge means is provided to allow the unitary
assembly of reflector B, reflector C and light transmitting
enclosure D to be rotated or tilted away from the lamp housing A
from the position as shown in FIG. 2 to the position shown in FIG.
7. As shown in FIGS. 2, 5 and 7, a pair of spaced bottom hinge
members 82 are secured to the support member 40. The hinge members
are in the form of bent wires which are secured in place by screws
84 threaded into tapped holes formed in the support member 40. The
upper support member 44 is provided with a pair of aligned, spaced
hinge members 86 cooperable with or hooked about the hinge members
82. The hinge members 86 are similarly secured to the upper support
member 44.
The assembly of reflectors and light transmitting enclosure movable
as a unit about the hinge members assures the concentricity of the
reflectors with respect to a lamp mounted within the housing at all
times. It will be apparent that to tilt the assembly from the
position shown in FIG. 2 to the position shown in FIG. 7, the
screws 46 are first removed to disconnect the assembly from the
lamp housing, and after tilting and lamping or relamping, the
screws are rethreaded into the parts to secure their
connection.
With a collecting reflector B having a reflecting surface 54 of a
curvature as shown in FIG. 2, the light rays have the paths
indicated by the lines a, b and c. Light is shown coming mainly
from the light producing element 38 of the lamp, such light rays
being indicated by the solid lines a. This is not strictly accurate
since much of the light bounces off the reflecting inner surface of
the lamp, where the lamp is of the reflector type. However, for the
purpose of representing the rays of light or light paths, this
manner of illustration is the most simple and is generally
indicative of the manner of operation. In any event, the rays of
light which are directed to the reflecting surface 55 of the
distributing reflector C without striking the collecting reflector
B to any appreciable extent are indicated by the solid lines a. The
rays of light which strike the upper portion of the collecting
reflector B are shown by the dash-dash lines b, and the light rays
which strike the lower portion of the collecting reflector and
directed to the distributing reflector are indicated by the
dot-dash lines c. The direct rays a may be divided basically into
two types. Those striking the narrow outer return edge of the
distributing reflector C are directed generally downward to light
up the area directly below the device. The rays striking the
greater center portion of the distributing reflector C are directed
out at wider angles off the vertical up to a maximum of
approximately 60.degree. off vertical. Several of the light rays
which leave the distributing reflector at the maximum of 60.degree.
are illustrated to show the broad surface area of the reflector
which is directing light out, and will therefore appear bright when
viewed at a 60.degree. angle off vertical (see the lines a
following the reflector contour).
The light rays b reflected off the upper portion of the collecting
reflector B are directed outwardly by the distributing reflector C
at angles which generally are between those of the downward
component rays b and the maximum 60.degree. components of such
light rays. The light rays b function as fill and support the light
between the maximum and minimum angles of these components.
The light rays c leaving the lamp L at an angle of 40.degree. to
50.degree. are reflected off the lower portion of the adjoining
collecting reflector B, cross over to the opposite side of the
center line o and are directed out through the light transmitting
enclosure D by the distributing reflector C at a high angle, or an
angle up to approximately 70.degree. off vertical. Some of the
light rays which leave the distributing reflector at 70.degree. ,
as illustrated, show the broad surface area of the distributing
reflector which is reflecting light out, and therefore a bright
appearance is furnished when viewed at a 70.degree. angle off the
vertical.
The above described light distribution is accomplished with the
lamp completely hidden from view, the lamp being surrounded by the
opaque housing. No light leaves the fixture at angles higher than
approximately 72.degree. vertical. The light leaving the
distributing reflector C at near 70.degree. has emanated from the
lamp at approximately 45.degree.. With the light distribution
afforded by a mercury vapor lamp having a given candle power at
45.degree. from the beam axis which is close to maximum, the
lighting fixture of the invention distributes a substantial amount
of light below 70.degree. and hardly any light above 72.degree..
This sharp break in light distribution is highly desirable; light
is spread over a wide area while complete glare cutoff is obtained
at a viewing angle which is as high as possible off the horizontal
plane. Also, when the viewer looks at the fixture at angles just
within the illumination zone, the brightness on the distributing
reflector C is spread over a broad area furnished by its surface.
It is therefore less disturbing to the viewer than would be the
same amount of light coming from a small source.
When the amount of light is traced which is reflected at various
angles from the fixture, it is found that the emitted candle power
is lowest near the vertical central axis o of the fixture, and
increases in a relatively smooth curve out to 60.degree. and then
decreases somewhat to 70.degree. at which point the illumination is
substantially cut off. Thus, a foot-candle distribution on the
horizontal plane which is relatively even from the central vertical
axis of the device out beyond 60.degree. is softened at about
70.degree. to eliminate a sharp delineation at the edges of these
zones. As a result, the fixture of the invention produces an even
distribution of light over a wide area while affording extremely
low glare.
With a collecting reflector B having the contour shown in FIG. 2, a
light distribution pattern is obtained as schematically shown in
FIG. 9. Such distribution pattern may be termed a "wide angle"
pattern as furnished by a reflector having its reflecting surface
54 at a relatively narrow angle, the angle x as shown in FIG. 6,
with respect to the central axis o of the fixture.
The light distribution pattern may be readily changed without
changing the dimensions of the fixture by simply substituting a
differently angled collecting reflector. The outer diameter of the
reflector also is not increased. As shown in FIG. 6, segments of a
reflector B' may be adhered by a suitable cement 90 to the
underlying reflector B having the described contour of reflecting
surface 54. The reflecting surface of the reflector segment or
segments B' is designated 54', and furnishes a "narrow angle" light
distribution pattern. As compared to reflector B, a reflector B',
or segments B', have a reflecting surface 54' which is at an
increased angle, the angle x' (FIG. 6), with respect to the
longitudinal center line o of the fixture.
In terms of light distribution pattern, it will be apparent that
the entire "wide angle" collecting reflector B may be replaced by
an entire "narrow angle" reflector B', whereupon, an illumination
pattern, as schematically shown in FIG. 10, will be obtained. With
the narrow angle collecting reflector B', the rays of light are as
indicated in FIG. 6. Essentially, the light rays are prevented from
crossing over from one side of the reflector to the opposite side,
and in this way, the high angle of light distribution is
eliminated. With a narrow angle collecting reflector, the maximum
angle of light emitted through the light transmitting enclosure D
is at an angle of approximately 60.degree. caused by the light
which goes directly to the distributing reflector. Whereas, with a
wide angle collecting reflector as shown in FIG. 2, light emitted
at the 60.degree. angle is spread over a wide surface of the
distributing reflector C, with a narrow angle reflector, the
distribution of light is confined to a reduced surface of the
distributing reflector. As in the case of wide angle distribution
on the order of 70.degree., a viewer, nevertheless, looking at the
fixture within the illumination zone would be less disturbed by the
large area of brightness than he would be by a smaller area having
the same total brightness.
Where a plurality of narrow angle reflector segments B' are
associated with a wide angle reflector B therebeneath, illumination
patterns such as schematically shown in FIGS. 11 and 12 may be
obtained. It will be apparent that different illumination patterns
may be obtained by changing the positions of the narrow angle
reflector segments with respect to the underlying wide angle
reflector.
Where, as shown in FIG. 1, the enclosure has a rectangular or
square configuration, the outside contour of the lamp housing A may
be made with flat planar surfaces to carry out the esthetic theme
of such configuration; also, the dome member 62 which supports the
distributing reflector C may also be made of a square outline.
Where, as shown in FIG. 8, the light transmitting enclosure,
designated D', is made round or circular, the esthetic theme of
circularity may be kept by making the outer contour of the lamp
housing A' of such contour, also the contour of the dome member
62'.
It will be apparent that a lighting fixture having a circular light
transmitting enclosure may be mounted on a single pole in lieu of
the square enclosure as shown in FIG. 1. A plurality of lighting
fixtures having circular light transmitting enclosures may be
mounted on hollow crossbars extending from a pole P' as shown in
FIG. 8. Two or four lighting fixtures may be so mounted; also
different configurations of light transmitting enclosures may be
used rather than the illustrated square and round.
The advantages and improved results of the invention will be
apparent from the foregoing description of a preferred embodiment
of the invention. Various changes and configurations may be made
without departing from the spirit and scope of the invention as
sought to be defined in the following claims.
* * * * *