U.S. patent number RE37,310 [Application Number 09/149,928] was granted by the patent office on 2001-08-07 for compact fluorescent luminaire.
This patent grant is currently assigned to Sylvan R. Shemitz Designs, Inc.. Invention is credited to Sylvan R. Shemitz.
United States Patent |
RE37,310 |
Shemitz |
August 7, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Compact fluorescent luminaire
Abstract
An arrangement for two side-by-side elongated lamps in a
lighting fixture in which lampholders are alternately mounted on
opposite sideplates or brackets of the lighting fixture. The
lighting fixture has an inside dimension that is longer than the
length of each lamp/lampholder combination by a length sufficient
to prevent the distal end of each lamp from overlapping the exposed
plug portion and the lampholder of any of the adjacent lamps. The
lamps are tightly gathered, and are close enough together to
simulate a hairline light source having an optical centerline
coincident with the optical centerline of the fixture.
Inventors: |
Shemitz; Sylvan R. (Woodbridge,
CT) |
Assignee: |
Sylvan R. Shemitz Designs, Inc.
(West Haven, CT)
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Family
ID: |
26847162 |
Appl.
No.: |
09/149,928 |
Filed: |
September 9, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
349987 |
Dec 6, 1994 |
05555162 |
Sep 10, 1996 |
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Current U.S.
Class: |
362/225; 362/260;
362/347 |
Current CPC
Class: |
F21V
7/005 (20130101); F21Y 2113/00 (20130101); F21Y
2103/37 (20160801) |
Current International
Class: |
F21V
7/00 (20060101); F21S 003/00 () |
Field of
Search: |
;362/147,217,225,260,347 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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854172 |
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Sep 1977 |
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BE |
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34 20 645 |
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Dec 1985 |
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DE |
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42 02 754 |
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Mar 1993 |
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DE |
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7-21809 |
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Jan 1995 |
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JP |
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WO92/13231 |
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Aug 1992 |
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WO |
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Other References
"Options Series" data sheet, SPI Lighting Inc., 1993. .
International Lighting Review, 1994/2 (2nd Quarter 1994), pp.
60-62. .
"Lightfair 1994--New Products," Elliptipar, Inc., May
1994..
|
Primary Examiner: Tso; Laura K.
Attorney, Agent or Firm: Fish & Neave Ingerman; Jeffrey
H. Tuma; Garry J.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of, commonly-assigned United States
patent application Ser. No. 08/233,374, filed Apr. 26, 1994, now
U.S. Pat. No. 5,434,762.
Claims
What is claimed is:
1. A lighting fixture for producing enhanced lamp light output
density, said fixture comprising:
a reflector having a first end and a second end, a fixture optical
centerline extending between said ends, and a fixture length along
said fixture optical centerline;
at least a first lampholder and a second lampholder, said first
lampholder mounted substantially adjacent said first end of said
reflector and said second lampholder mounted substantially adjacent
said second end of said reflector, each said lampholder being
mounted at that lampholder's respective location such that a
projection of said first lampholder along said fixture optical
centerline toward said second lampholder partially overlaps said
second lampholder, and such that a projection of said second
lampholder along said fixture optical centerline toward said first
lampholder partially overlaps said first lampholder, each said
lampholder having a lampholder length;
at least two elongated lamps, each lamp having:
a plug portion for mating with one of said lampholders, said plug
portion having a plug portion length,
a distal portion opposite said plug portion,
a lamp longitudinal axis running from said plug portion to said
distal portion, and
a lamp length along said lamp longitudinal axis from said plug
portion to said distal portion; wherein
each of said lamps is mounted in one of said lampholders such that
said lamps are tightly gathered to simulate a hairline source, and
the lamp longitudinal axes of said lamps are substantially parallel
to the optical centerline and are offset from one another;
a portion of said plug portion remains exposed when said lamp is
mounted in said lampholder, said exposed portion having an exposed
plug portion length;
said fixture length is sufficiently greater than the sum of:
the lamp length of one of said lamps,
the exposed plug portion length of said one of said lamps,
the lampholder length of one of said lampholders associated with
said one of said lamps,
the exposed plug portion length of the plug portion of another of
said lamps, and
the lampholder length of the lampholder associated with said other
of said lamps, that:
for adjacent lamps, being associated with lampholders mounted
adjacent different ends of said reflector, the distal portion of
any one of said lamps longitudinally clears the lampholder
associated with, and the exposed plug portion of, any of said lamps
adjacent said one of said lamps;
and
said lamps together form a lamp optical centerline substantially
coincident with said fixture optical centerline.
2. The lighting fixture of claim 1 wherein:
exactly one of said lampholders is mounted adjacent each said end
of said reflector.
3. The lighting fixture of claim 1 wherein:
each of said lamps comprises at least one light-emitting tube
having a tube diameter; and
said at least one light-emitting tubes of adjacent ones of said
lamps are spaced apart by between about 20% and about 40% of said
tube diameter.
4. The lighting fixture of claim 3 wherein each of said lamps is a
twin-tube lamp.
5. The lighting fixture of claim 4 wherein:
each tube of each of said twin-tube lamps has a longitudinal axis
and a tube center through which said longitudinal axis passes;
the longitudinal axes of the two tubes of each respective one of
said lamps define a respective plane; and
said respective planes of said lamps are substantially parallel to
one another.
6. The lighting fixture of claim 5, wherein:
exactly one lampholder is mounted adjacent each said end of said
reflector, such that there are two said lamps and four said tubes;
and
the four tube centers, in cross-section, substantially form a
rectangle.
7. The lighting fixture of claim 6, wherein said rectangle is
substantially square.
8. A lighting fixture for producing enhanced lamp light output
density, comprising:
a reflector and two substantially parallel sideplates defining a
cavity having a light transmissive front, said reflector having a
fixture optical centerline;
a respective standard 4-pin compact fluorescent lampholder mounted
on each of the sideplates; and
a respective twin-tube lamp mounted in each respective one of the
lampholders; wherein:
there is a first said twin-tube lamp and a second said twin-tube
lamp and four said tubes;
each tube of each of said twin-tube lamps has a tube center;
the two tubes of each of said respective twin-tube lamps define a
respective lamp plane;
the length of the cavity is approximately 1.5" greater than
substantially the combined length of one said twin-tube lamp and
said respective lampholder associated with said one said twin-tube
lamp;
the lamps, when mounted in the lampholders, are spaced
approximately 1/8" to 1/4" apart from each other;
the lamp plane of said first lamp is parallel to the lamp plane of
said second lamp;
the four tube centers of said lamps, viewed along said longitudinal
axes, substantially form a square; and
the four tubes of said lamps together have a lamp optical
centerline substantially coincident with said fixture optical
centerline.
9. The lighting fixture of claim 1 further comprising a first
sideplate at said first end of said reflector and a second
sideplate at said second end of said reflector, said first
lampholder being mounted on said first sideplate and said second
lampholder being mounted on said second sideplate.
10. The lighting fixture of claim 9 wherein said sideplates are
brackets suitable for holding said lampholders and which enable
light from said lamps to radiate from said first and second ends of
said reflector.
11. A lighting fixture for producing enhanced lamp light output
density, for use with at least two elongated lamps, each lamp
having:
a plug portion, said plug portion having a plug portion length,
a distal portion opposite said plug portion,
a lamp longitudinal axis running from said plug portion to said
distal portion, and
a lamp length along said lamp longitudinal axis from said plug
portion to said distal portion; said fixture comprising:
a reflector having a first end and a second end, a fixture optical
centerline entending between said ends, and a fixture length along
said fixture optical centerline;
at least a first lampholder and a second lampholder, said first
lampholder mounted substantially adjacent said first end of said
reflector and said second lampholder mounted substantially adjacent
said second end of said reflector, each said lampholder being
mounted at that lampholder's respective location such that a
projection of said first lampholder along said fixture optical
centerline toward said second lampholder partially overlaps said
second lampholder, and such that a projection of said second
lampholder along said fixture optical centerline toward said first
lampholder partially overlaps said first lampholder, each said
lampholder having a lampholder length; wherein, when each of said
lamps is mounted with said lamp's respective plug portion in one of
said lampholders such that said lamps are tightly gathered to
simulate a hairline source, and the lamp longitudinal axes of said
lamps are substantially parallel to the optical centerline and are
offset from one another:
a portion of said plug portion remains exposed, said exposed
portion having an exposed plug portion length;
said fixture length is sufficiently greater than the sum of:
the lamp length of one of said lamps,
the exposed plug portion length of said one of said lamps,
the lampholder length of one of said lampholders associated with
said one of said lamps,
the exposed plug portion length of the plug portion of another of
said lamps, and
the lampholder length of the lampholder associated with said other
of said lamps, that:
for adjacent lamps, being associated with lampholders mounted
adjacent different ends of said reflector, the distal portion of
any one of said lamps longitudinally clears the lampholder
associated with, and the exposed plug portion of, any of said lamps
adjacent said one of said lamps;
and
said lamps together form a lamp optical centerline substantially
coincident with said fixture optical centerline.
12. The lighting fixture of claim 11 wherein exactly one of said
lampholders is mounted adjacent each said end..Iadd.
13. A lighting fixture for producing enhanced lamp light output
density, said fixture comprising:
a reflector having two substantially parallel sideplates defining a
cavity having a light transmissive front, said reflector having a
fixture optical centerline extending between said sideplates, said
cavity having a cavity length along said fixture optical
centerline;
at least one respective lampholder mounted on each one of said
sideplates, each said lampholder being mounted at its respective
location such that a projection of one lampholder along said
fixture optical centerline toward another said lampholder partially
overlaps the other said lampholder, each said lampholder having a
lampholder length;
at least two elongated lamps, each lamp having:
a plug portion for mating with one of said lampholders, said plug
portion having a plug portion length,
a distal portion opposite said plug portion,
a lamp longitudinal axis running from said plug portion to said
distal portion, and
a lamp length along said lamp longitudinal axis from said plug
portion to said distal portion; wherein
each of said lamps is mounted in one of said lampholders such that
said lamps are tightly gathered to simulate a hairline source, and
the lamp longitudinal axes of said lamps are substantially parallel
to the optical centerline and are offset from one another;
a portion of said plug portion remains exposed when said lamp is
mounted in said lampholder, said exposed portion having an exposed
plug portion length;
said cavity length is sufficiently greater than the sum of:
the lamp length of one of said lamps,
the exposed plug portion length of said one of said lamps,
the lampholder length of one of said lampholders associated with
said one of said lamps,
the exposed plug portion length of the plug portion of another of
said lamps, and
the lampholder length of the lampholder associated with said other
of said lamps, that:
for adjacent lamps, being associated with lampholders mounted on
different sideplates of said reflector, the distal portion of any
one of said lamps longitudinally clears the lampholder associated
with, and the exposed plug portion of, any of said lamps adjacent
said one of said lamps; and
said lamps together form a lamp optical centerline substantially
coincident with said fixture optical centerline..Iaddend..Iadd.
14. The lighting fixture of claim 13 wherein said sideplates
comprise brackets suitable for holding said lampholders without
occluding light from said lamps..Iaddend..Iadd.
15. The lighting fixture of claim 13 wherein said reflector has a
first end and a second end, one of said sideplates being located at
said first end and the other of said sideplates being located at
said second end..Iaddend..Iadd.
16. The lighting fixture of claim 13 wherein:
said reflector has at least three substantially parallel
sideplates, at least one adjacent pair of said sideplates defining
a cavity having a light transmissive front, said cavity having a
cavity length along said fixture optical centerline;
each said lampholder is mounted at its respective location such
that a projection of one lampholder along said fixture optical
centerline toward another said lampholder mounted on an adjacent
sideplate partially overlaps the other said lampholder; and
said cavity length is sufficiently greater than the sum of:
the lamp length of one of said lamps,
the exposed plug portion length of said one of said lamps,
the lampholder length of one of said lampholders associated with
said one of said lamps,
the exposed plug portion length of the plug portion of another of
said lamps, and
the lampholder length of the lampholder associated with said other
of said lamps, that:
for adjacent lamps, being associated with lampholders mounted on
adjacent sideplates of said reflector, the distal portion of any
one of said lamps longitudinally clears the lampholder associated
with, and the exposed plug portion of, any of said lamps adjacent
said one of said lamps; and
said lamps together form a lamp optical centerline substantially
coincident with said fixture optical centerline..Iaddend..Iadd.
17. The lighting fixture of claim 13 wherein:
exactly one of said lampholders is mounted on each one of said
sideplates..Iaddend..Iadd.
18. The lighting fixture of claim 13 wherein:
each of said lamps comprises at least one light-emitting tube
having a tube diameter; and
said at least one light-emitting tubes of adjacent ones of said
lamps are spaced apart by between about 20% and about 40% of said
tube diameter..Iaddend..Iadd.
19. The lighting fixture of claim 18 wherein each of said lamps is
a twin-tube lamp..Iaddend..Iadd.
20. The lighting fixture of claim 19 wherein:
each tube of each of said twin-tube lamps has a longitudinal axis
and a tube center through which said longitudinal axis passes;
the longitudinal axes of the two tubes of each respective one of
said lamps define a respective plane; and
said respective planes of said lamps are substantially parallel to
one another..Iaddend..Iadd.
21. The lighting fixture of claim 20 wherein:
exactly one lampholder is mounted on each one of said sideplates,
such that there are two said lamps and four said tubes; and
the four tube centers, in cross-section, substantially form a
rectangle..Iaddend..Iadd.
22. The lighting fixture of claim 21 wherein said rectangle is
substantially square..Iaddend..Iadd.
23. A lighting fixture for producing enhanced lamp light output
density, for use with at least two elongated lamps, each lamp
having:
a plug portion, said plug portion having a plug portion length,
a distal portion opposite said plug portion,
a lamp longitudinal axis running from said plug portion to said
distal portion, and
a lamp length along said lamp longitudinal axis from said plug
portion to said distal portion; said fixture comprising:
a reflector having a first sideplate and a second sideplate, said
sideplates defining a cavity, said reflector having a fixture
optical centerline extending between said sideplates, said cavity
having a cavity length along said fixture optical centerline;
at least a first lampholder and a second lampholder, said first
lampholder mounted on said first sideplate and said second
lampholder mounted on said second sideplate, each said lampholder
being mounted at that lampholder's respective location such that a
projection of said first lampholder along said fixture optical
centerline toward said second lampholder partially overlaps said
second lampholder, and such that a projection of said second
lampholder along said fixture optical centerline toward said first
lampholder partially overlaps said first lampholder, each said
lampholder having a lampholder length; wherein, when each of said
lamps is mounted with said lamp's respective plug portion in one of
said lampholders such that said lamps are tightly gathered to
simulate a hairline source, and the lamp longitudinal axes of said
lamps are substantially parallel to the optical centerline and are
offset from one another:
a portion of said plug portion remains exposed, said exposed
portion having an exposed plug portion length;
said cavity length is sufficiently greater than the sum of:
the lamp length of one of said lamps,
the exposed plug portion length of said one of said lamps,
the lampholder length of one of said lampholders associated with
said one of said lamps,
the exposed plug portion length of the plug portion of another of
said lamps, and
the lampholder length of the lampholder associated with said other
of said lamps, that:
for adjacent lamps, being associated with lampholders mounted on
different sideplates of said reflector, the distal portion of any
one of said lamps longitudinally clears the lampholder associated
with, and the exposed plug portion of, any of said lamps adjacent
said one of said lamps; and
said lamps together form a lamp optical centerline substantially
coincident with said fixture optical centerline..Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates to lighting fixtures. More particularly,
this invention relates to lighting fixtures utilizing two elongated
lamps to produce increased lamp light output density.
One goal of the lighting industry has been to provide
luminaires--lighting fixtures with lamps--with ever higher lamp
light output densities. Light output density is generally measured
in lumens/foot (L/F), a lumen being a unit of luminous flux. For
example, a two-foot-long (approximately 0.61-meter--long) lamp that
produces 1000 lumens achieves 500 L/F (approximately 1,639
L/Meter).
One manner of providing a higher lamp light output density has been
to use high output lamps, which achieve a greater luminous flux
(measured in lumens) from the same size lamp. For example, while a
typical four-foot-long (approximately 1.22-meter-long), 32 -watt,
T8-size, rapid start lamp will produce a luminous flux of 2,950
lumens, for 737 L/F (approximately 2,418 L/M), a typical
four-foot-long (approximately 1.22-meter-long), 60-watt, T12-size
High Output rapid start lamp will produce a luminous flux of 4,350
lumens, for 1,087 L/F (approximately 3,566 L/M), an increase of
approximately 50% in light output density.
Another manner of achieving greater light output density from a
given luminaire has been through use of compact fluorescent lamps
(CFL), such as twin-tube lamps, which produce a greater number of
lumens, at approximately the same wattage, than are produced by
larger conventional lamps. For example, while a typical
four-foot-long (approximately 1.22-meter-long), 32-watt T8-size,
rapid start lamp will produce a luminous flux of 2,950 lumens, for
737 L/F (approximately 2,418 L/M), a typical 16.5"-long
(approximately 42-centimeter-long), 39 watt, T5-size rapid start
CFL sold by General Electric Co. under the name Biax.RTM. produces
a luminous flux of 2,850 lumens, for 2,073 L/F (approximately 6,800
L/M), an increase of approximately 180% in light output density.
Similar lamps are sold by Philips, North America under the
trademark PL-L.RTM. and by Osram under the trademark Dulux
L.RTM..
A higher light output density value for a lighting fixture can be
achieved by providing an array of lamps in as small a
cross-sectional area as possible. However, attempts to utilize this
manner of achieving a greater light output density are inherently
constrained by the dimensions of lampholders. For example, the
width of a standard 4-pin plug-in compact fluorescent lampholder,
which is greater than the width of the lamp it is designed to hold,
prevents the light-emitting tubes of the CFL lamps from being
placed as close together as desired to produce the greatest lamp
light output density, as when two of the lamps are placed
essentially side-by-side.
The placement of two lamps side-by-side is desirable for several
reasons. First, as suggested above, placement of multiple lamps
side-by-side increases the numerator in the L/F calculation,
serving to increase the overall value of light output density of a
luminaire. For example, two 16.5"-long, 39 watt, twin-tube CFL
lamps, placed side-by-side, would produce 5,700 lumens, for 4,145
L/F (approximately 13,540 L/M), an increase of approximately 100%
in light output density, as compared to one 16.5"-long, 39 watt,
twin-tube CFL lamp, or an increase of 462% over the four-foot-long,
32-watt, T8-size, rapid start lamp described above. Additionally,
the light emitted from multiple hairline light sources, when placed
adjacent one another, simulates the light that would be emitted
from one, larger, hairline light source. As such, the light from
the multiple sources is easier to direct and control by
conventional reflectors or lenses that are designed for hairline
light sources. Commonly used reflectors provide either elliptical
or parabolic arcs, or both. For example, a reflector with both
elliptical and parabolic arcs is sold by Elliptipar, Inc., of West
Haven, Conn., under the trademark ELLIPTIPAR.RTM..
Therefore, it would be desirable to provide an arrangement for
orienting multiple elongated lamps in a lighting fixture that
allows the placement of the multiple lamps closer together than
would normally be allowed by the size of the lampholders.
It would also be desirable to provide an arrangement for orienting
multiple elongated lamps in a lighting fixture that allows the
placement of the multiple lamps such that they simulate, as closely
as possible, a hairline source of light.
SUMMARY OF THE INVENTION
It is an object of this invention to provide an arrangement for
orienting multiple elongated lamps in a lighting fixture that
allows the placement of the multiple lamps closer together than
would normally be allowed by the size of the lampholders.
It is also an object of this invention to provide an arrangement
for orienting multiple elongated lamps in a lighting fixture that
allows the placement of the multiple lamps such that they are
tightly gathered to simulate a hairline source of light, and in
particular a hairline source of light centered on the focus or
optical center of the reflector.
In accordance with this invention, there is provided a lighting
fixture for producing enhanced lamp light output density. The
fixture includes a reflector having two ends, a fixture optical
centerline extending between the ends, and a fixture length along
the fixture optical centerline. At least one lampholder is mounted
substantially adjacent each of the ends of the reflector, each
lampholder being mounted at its respective location such that a
projection of each lampholder along the fixture optical centerline
toward the other lampholder partially overlaps the other
lampholder. Each lampholder has a lampholder length. The fixture
further includes at least two elongated lamps, each lamp having a
plug portion for mating with one of the lampholders, the plug
portion having a plug portion length, a distal portion opposite the
plug portion, a lamp longitudinal axis running from the plug
portion to the distal portion, and a lamp length along the lamp
longitudinal axis from the plug portion to the distal portion. Each
of the lamps is mounted in one of the lampholders such that the
lamp longitudinal axes of the lamps are substantially parallel to
the optical centerline and are offset from one another. A portion
of the plug portion remains exposed when the lamp is mounted in the
lampholder. The exposed portion has an exposed plug portion length.
The fixture length is sufficiently greater than the sum of: (1) the
lamp length of one of said lamps, (2) the exposed plug portion
length of that one of the lamps, (3) the lampholder length of one
of the lampholders associated with that one of the lamps, (4) the
exposed plug portion length of the plug portion of another of the
lamps, and (5) the lampholder length of the lampholder associated
with the other of the lamps, that for adjacent lamps, being
associated with lampholders mounted adjacent different ends of the
reflector, the distal portion of any one of the lamps
longitudinally clears the lampholder associated with, and the
exposed plug portion of, any of the lamps adjacent that one of the
lamps; and the lamps together form a lamp optical centerline
substantially coincident with the fixture optical centerline.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects and advantages of the invention will be
apparent upon consideration of the following detailed description,
taken in conjunction with the accompanying drawings, in which like
reference characters refer to like parts throughout, and in
which:
FIG. 1 is a front view of preferred embodiment of a lighting
fixture according to the present invention containing two
lamps;
FIG. 2 is a perspective view of the lighting fixture of FIG. 1;
FIG. 3A is a cross-sectional view of the lighting fixture of FIG.
1, taken from line 3A--3A of FIG. 1;
FIG. 3B is a cross-sectional view of the lighting fixture of FIG.
1, taken from line 3B--3B of FIG. 1;
FIG. 4A is a cross-sectional view, similar to FIG. 3A, of the
lighting fixture of FIG. 1 with the lamps removed; and
FIG. 4B is a cross-sectional view, similar to FIG. 3B, of the
lighting fixture of FIG. 1 with the lamps removed.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides an arrangement for lighting fixtures
that produces a greater lamp light output density--i.e., more
luminous flux (measured in lumens) from a smaller, more compact
array of lamps--than could otherwise be obtained. This is achieved
by mounting the lampholders for adjacent lamps on opposite
sideplates of the lighting fixture and by increasing the inside
dimension of the lighting fixture enough to accommodate the
presence of lampholders at both ends. In this way, the lampholder
for each lamp does not interfere with any portion of any adjacent
lamp and the lampholders are no longer a limiting factor in how
close the lamps can be to one another. The lamps can therefore be
mounted close enough together so that they are tightly gathered and
simulate a hairline source having an effective optical centerline
substantially coincident with the optical centerline, or focus, of
the reflector of the lighting fixture.
A preferred embodiment of a lighting fixture designed according to
the present invention, with two compact fluorescent lamps, is
illustrated in FIGS. 1-4B. Lighting fixture 10 includes a reflector
11 and sideplates 20 and 21. Reflector 11 preferably is the
elliptical-parabolic reflector referred to above, which has a
focus, or optical centerline, 22. One lampholder 30, illustrated in
FIG. 4A as a standard 4-pin compact fluorescent lampholder, is
mounted on sideplate 20. The other lampholder 31, illustrated in
FIG. 4B as also being a standard 4-pin compact fluorescent
lampholder, is mounted on sideplate 21. Lamp 40 is plugged into
lampholder 30, while lamp 41 is plugged into lampholder 31. Lamps
40 and 41 are illustrated in FIGS. 1, 2, 3A and 3B as being
twin-tube compact fluorescent lamps.
Sideplates 20, 21 are illustrated as preferably being full plates,
e.g. in FIG. 2. However, this need not be the case. Sideplates 20,
21 may also preferably be cutaway (skeletal) plates, or brackets,
or any other structure suitable for holding lampholders 30, 31
without occluding light, and therefore suitable for enabling
continuous rows of luminaires to be made.
As seen in FIGS. 2, 3A and 3B, the widths of lampholders 30, 31 are
greater than the widths of lamps 40, 41. Therefore, if lampholders
30, 31 were both mounted on sideplate 20 or both mounted on
sideplate 21, a substantial gap, approximately 100% to 120% of the
diameter of the light-emitting tubes 50, 51 of lamps 40, 41, would
necessarily exist between light-emitting tubes 50, 51. This
arrangement is not conducive to maximum optical control.
In the embodiment illustrated in FIGS. 1-4B, however, optical
control of lighting fixture 10 is enhanced through placement of the
light-emitting tubes 50, 51 of lamps 40, 41 close together, in an
arrangement approaching a hairline source having an optical
centerline 32, indicated by the intersection of lines 33, 34
passing through the tube centers of tubes 50, 51. Lampholder 30 is
mounted on sideplate 20, while lampholder 31 is mounted on
sideplate 21. The lampholders are positioned so that a portion of
the projection of lampholder 30 onto sideplate 21 overlaps a
portion of lampholder 31. By mounting lampholders 30, 31 in this
manner, the gap between lamps 40, 41 that would otherwise be
necessitated by mounting lampholders 30, 31 on the same sideplate
may be partially or completely eliminated, as desired. As shown,
optical centerline 32 of the effective hairline source formed by
tightly gathered lamps 40, 41 substantially coincides with focus or
optical centerline 22 of reflector 11, allowing maximum control by
reflector 11 of the light output.
The inside dimension 60 of the lighting fixture 10 illustrated in
FIGS. 1 and 2 along its longitudinal axis (the axis running from
sideplate 20 to sideplate 21) is greater than essentially the
combination of the lengths of either lampholder 30 and lamp 40 or
lampholder 31 and lamp 41, which is essentially all that would have
been required in a standard luminaire (plus room for
installation/removal). Increased length 60 of the inside of
lighting fixture 10 allows the distal end 42 of lamp 40 (the "U"
portion connecting the two linear portions of the light-emitting
tubes) to longitudinally clear the lampholder 31 and the plug
portion of lamp 41. Similarly, the distal end 43 of lamp 41
longitudinally clears lampholder 30 and the plug portion of lamp
40. This feature allows the placement of the light-emitting tubes
50, 51 of lamps 40, 41 as close together as may be desirable.
In the preferred embodiment illustrated in FIGS. 1-4B, using
standard 4-pin plug-in compact fluorescent lampholders and standard
4-pin plug-in lamps, the inside dimension 60 of the lighting
fixture 10 is approximately 1.5" greater than either
lamp/lampholder combination. The actual increase necessary in this
dimension, however, is dependent on the particular lampholder and
lamp being utilized. For lampholders that present a greater
profile, a larger increase may be necessary. In any event, the
increase in the inside dimension of the lighting fixture must be
large enough to allow the distal end of each lamp to clear the plug
portion and lampholder of the other lamp, so that the
light-emitting tubes of two adjacent lamps could, if desired, be
mounted in contact with each other, and to allow room for
installation/removal.
In the preferred embodiment, the plane of one lamp, defined by the
longitudinal axes of the lamp's two cylindrical legs, is parallel
to the corresponding plane of the other lamp. The four
tube-centers, in cross-section, form a square, or a nearly-square
rectangle.
As seen in FIG. 1, in the preferred embodiment, lampholders 30, 31
have been mounted on sideplates 20, 21 such that the longitudinal
axis of lamp 40 when mounted in lampholder 30 is elevated slightly
relative to the longitudinal axis of lamp 41 when mounted in
lampholder 31.
In the embodiment disclosed in FIGS. 1-4B, a small gap is provided
between the lamps 40, 41. This gap serves several purposes. First,
the gap between the adjacent lamps 40, 41 allows for relatively
unencumbered emission of light, whether that light is direct
radiation or reflected light. Rather than being forced to travel
through the light-emitting tubes of the adjacent lamp before
exiting the luminaire, a greater portion of the light emitted from
an individual lamp will have a direct transmission route from the
luminaire through this space. Second, this gap facilitates the
circulation of cooling air. If the light-emitting tubes of adjacent
lamps touched, a portion of the path otherwise travelled by
circulating air would be eliminated. Finally, this gap provides for
access by a screwdriver or other tool, for example for removal of
screws securing the reflector, in situations where such access
might not otherwise be available. The recommended gap between lamps
40, 41 is between about 20% and about 40% of the diameter of the
light-emitting tubes 50, 51 of lamps 40, 41.
It should be apparent that any number of lampholders may be used in
lighting fixtures designed according to the present invention,
provided the lampholder for each individual lamp is mounted on a
different sideplate (or bracket) from the lampholder for any lamps
directly adjacent that individual lamp.
Thus it is seen that a lighting fixture for providing greater lamp
light output density with better optical control is provided. One
skilled in the art will appreciate that the present invention can
be practiced by other than the described embodiments, which are
presented for purposes of illustration and not of limitation, and
the present invention is limited only by the claims which
follow.
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