Note: Descriptions are shown in the official language in which they were submitted.
CA 02731820 2013-01-18
LUMINAIRES AND LIGHT ENGINES FOR SAME
Field of the Invention
Embodiments of the invention relate to luminaires and light engines for
same.
Background of the Invention
The use of light emitting diodes in luminaires is becoming more prevalent.
However, light emitting diodes have thermal management issues in that they
heat
up and lose efficiency in the process. Moreover, the light from light emitting
diodes is emitted at angles that can create hot spots (typically at nadir)
above the
light emitting diodes, rendering them undesirable in certain applications,
such as
uplight applications whereby light is directed onto the ceiling above the
luminaire.
Summary of the Invention
In one aspect, the present invention provides a luminaire comprising at
least one light engine comprising: a. a reflector comprising a reflective
surface; b.
at least one light emitting diode; and c. a heat sink comprising a linear
substrate
having a plurality of perforations that extend entirely through the substrate.
In
another aspect, the reflector comprises a base and a curved reflective surface
and
the at least one light emitting diode is retained on the base and the curved
reflective surface extends at least partially around the at least one light
emitting
diode. A portion of the reflector may be sandwiched between the at least one
light emitting diode and the heat sink.
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CA 02731820 2013-01-18
In some embodiments, an end of the reflector terminates above the light
emitting diodes to reduce the concentration of light directly above the light
emitting diodes but rather distribute the light outwardly from the luminaire.
Brief Description of the Figures
FIG. 1 is an exploded view of a light engine according to one embodiment of
the invention.
FIG. 2 is a side elevation view of the embodiment of the light engine shown
in FIG. 1 assembled.
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CA 02731820 2011-02-15
FIG. 3 is an exploded view of one embodiment of a luminaire that uses the
embodiment of the light engine shown in FIG. 1.
FIG. 4 is a top perspective view of the luminaire of FIG. 3 assembled but with
an end cap removed.
FIG. 5 is bottom perspective view of the luminaire shown in FIG. 3 assembled.
FIG. 6 is a top perspective view of the luminaire shown in FIG. 3 assembled.
FIG. 7 is an exploded view of another embodiment of a luminaire that uses
the embodiment of the light engine shown in FIG. 1.
FIG. 8 is bottom perspective view of the luminaire shown in FIG. 7 assembled.
FIG. 9 is a top perspective view of the luminaire shown in FIG. 7 assembled.
Detailed Description of Embodiments of the Invention
Embodiments provide a light engine 10 particularly suitable, but certainly not
limited, for use in luminaires for uplight applications (i.e., whereby the
light emitted
from the fixture is directed upwardly). In some embodiments, the light engine
10
includes a heat sink 12, a reflector 14, a plurality of light emitting diodes
16
mounted on a printed circuit board 18, and optionally an auxiliary optical
component 34.
Embodiments of the heat sink 12 can be formed from any metallic material
(such as, but not limited to, aluminum sheet metal) and can be perforated.
Perforations 20 of any geometric shape are contemplated herein, including, but
not
limited to, square, circular, oval, rectangular, triangular, hexagonal,
octagonal, etc.
Embodiments of the reflector 14 can also be formed of a metallic material
(such as, but not limited to, aluminum) and can include a base 22, an arm 24
that
extends upwardly from the base 22 and has a reflective surface 32, and two
ends 26,
28 that define an opening 30 therebetween. The reflective surface 32 of the
arm 24
may be of any shape but preferably is at least partially curved. In some
embodiments, the reflective surface 32 is semi-parabolic in shape. In some
embodiments, end 26 of the reflector arm 24 is designed to terminate above the
light
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emitting diodes 16 positioned in the reflector 14 (as described below). In
some
embodiments, the reflector arm 24 terminates above the light emitting diodes
16
between 00 to 30 (inclusive) off nadir. In some embodiments, the reflector
arm 24
terminates above the light emitting diodes 16 substantially at nadir.
The reflective surface 32 of the reflector 14 preferably has an extremely high
surface reflectivity, preferably, but not necessarily, between 96%-99.5%,
inclusive
and more preferably 98.5-99%. To achieve the desired reflectivity, in one
embodiment the reflective surface 32 comprises polished metals such as, but
not
limited to, polished aluminum. In some embodiments a reflective material for
use
in the reflector 14 comprises Miro reflective aluminum materials, available
from
Alanod-Solar GmbH & Co. Alternative materials include micro cellular
polyethylene ("MCPET"), available from Furukawa. In some embodimentsõ the
reflectivity of the reflective surface 32 can be further enhanced by the
application of
reflective coatings, including reflective paints, or other reflective
compositions. The
reflective surface 32 may include a layer of a reflective flexible sheet of
material such
as one or more of the materials sold under the tradenames GL-22, GL-80, GL-30
or
OptilonTM, all available from DuPont.
Light emitting diodes 16 (mounted on a printed circuit board 18) are
positioned on the base 22 of the reflector 14. The heat sink 12, reflector 14,
and
printed circuit board 18 may be secured together via any mechanical or
chemical
retention method. In one embodiment, they are fastened together with screws or
other mechanical fasteners (not shown).
In use, when the light emitting diodes 16 emit light, approximately half of
the
light is emitted upwardly and outwardly unencumbered from the light engine 10.
However, the light emitted from the side of the light emitting diodes 16
adjacent the
reflector arm 24 encounters the reflective surface 32, which reflects the
light to
asymmetrically distribute it at high angles. In this way, the amount of light
emitted
directly above the light emitting diodes 16 is significantly reduced and
redirected so
as to avoid the appearance of a hot spot (an area where the light appears
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particularly bright) directly above the light emitting diodes (i.e., at nadir)
but rather
creates the appearance of a more even and uniform light distribution.
Embodiments of the light engine 10 described herein have unique thermal
management properties built into their designs. First, use of a perforated
heat sink
12 allows air to circulate up and intimately around the light emitting diodes
16 for
convective cooling. Obviously the size, shape, and density of the perforations
20
provided in the heat sink 12 impact cooling efficiencies. Second, because the
reflector base 22 is sandwiched between the heat sink 12 and the printed
circuit
board 18 (with associated light emitting diodes 16), the reflector 14 becomes
an
integral part of the heat sinking mechanism. Intimate contact between the
reflector
14 and the printed circuit board 18 provides a direct path for conductive heat
transfer away from the light emitting diodes 16.
The light engine 10 optionally may include auxiliary optical components. In
one embodiment, a diffuser 34 is supported within the opening 30 between the
two
ends 26, 28 of the reflector 14 (see FIG. 2). Other optical components,
including, but
not limited to, films, lenses (perforated, colored, etc.), color filters, and
obstruction
media, may be so supported. One of skill in the art will understand that the
diffuser
34 (or other optical component) can be supported by the reflector 14 in a
variety of
ways. In some embodiments, the diffuser 34 is snapped or slid between the ends
26,
28 of the reflector (see FIG. 2). While the diffuser 34 may be permanently
affixed to
the reflector 14, it may be desirable to attach the diffuser 34 to the
reflector so as to
be easily removable from the reflector 14. In this way, auxiliary optical
components
maybe be easily switched out or substituted in the light engine 10 to tailor
or
customize the light distribution and/or appearance emitted from the light
engine.
In some embodiments, the diffuser 34 extends between the ends 26, 28 of the
reflector 14 in a straight or a concave plane. However, as discussed below, in
some
applications it may be beneficial for the diffuser to bow convexly outwardly
from
the opening 30.
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The light engine 10 may be incorporated into a variety of different types of
luminaires, only a few of which are described and shown herein for purposes of
illustration. It is by no means applicants intention to limit the utility of
embodiments of the light engines 10 described herein to these illustrated
luminaires.
Moreover, the light engine 10 may be provided in any length or other
dimension.
Multiple light engines 10 (or components thereof) may be linearly arranged and
electrically connected in a single luminaire.
Figures 3-6 illustrate an embodiment of a luminaire designed to be mounted
on a wall to direct light upwardly from the luminaire (hereinafter "wall mount
luminaire" 50). The wall mount luminaire 50 includes a base housing 52 and a
back
plate 54. The light engine 10 seats in the base housing 52 and the base
housing 52,
the light engine 10, and the back plate 54 may be secured together using any
mechanical fastening means, including screws (not shown). End caps 58 are
mounted on each end of the luminaire 50. The wall mount luminaire 50 may be
mounted on the wall using any mechanical retention method, all of which are
readily know by those of skill in the art. In the disclosed embodiment, a
bracket 60
is mounted on the wall and the back plate 54 includes a hook 53 that engages
the
bracket to retain the wall mount luminaire on the wall (see FIG. 4). When so
mounted, the bottom of the base housing 52 is visible from the floor. It may
be
desirable, but certainly not required, to provide an aesthetically pleasing
decorative
cover 62 below the base housing 52. Such a cover 62 might be wood, glass,
acrylic,
etc.
When the wall mount luminaire 50 is mounted on the wall and in use, the
light emitting diodes 16 are oriented upwardly in the luminaire 50. As
described
above, approximately half of the light emitted from the wall mount luminaire
50 is
emitted upwardly and outwardly from the luminaire 50 (i.e., onto the ceiling
in a
direction away from the wall). The other approximate half of the light emitted
from
the light emitting diodes 16 encounters the reflector 14, which emits the
light at a
high angle to reduce the concentration of light directly above the luminaire
50 (and
CA 02731820 2011-02-15
thus avoid hot spots) but rather distribute the light, and thereby increase
the
brightness, outwardly across the ceiling. Because the wall mount luminaire 50
is an
open fixture, heat generated by the light emitting diodes 16 is able to
dissipate from
the fixture. Heat dissipation is facilitated by the convective cooling effect
of the
perforated heat sink 12 as well as the conductive cooling effect of the
reflector 14, as
described above.
As alluded to earlier, it may be beneficial to incorporate an auxiliary
optical
component, such as a diffuser 34, into the light engine 10. The diffuser 34
may be
retained by the reflector 14, as discussed above. It may be desirable, but
certainly
not required, to position the diffuser 34 in the reflector 14 so that the
diffuser 34
bows outwardly from the reflector 14. In this way, the diffuser 34 is able to
direct
light onto the wall above the luminaire.
Figures 7-9 illustrate another embodiment of a luminaire 70 in which
embodiments of the light engine 10 described herein may be used. The luminaire
70
illustrated in Figures 7-9 is a pendant uplight that is suspended from the
ceiling. It
is noteworthy that the same base housing 52 and light engine 10 (as well as
optional
cover 62) used in the wall mount luminaire 50 can be used in the pendant
luminaire
70. To create the pendant luminaire version, essentially two light engines 10
and
two base housings 52 are positioned back to back (see FIG. 7) and secured
together
to each make up a half of the pendant luminaire 70. End caps 72 designed for
the
pendant luminaire 70 are provided on the ends of the luminaire 70. Moreover,
clips
73 may span adjacent light engines 10. Suspension means for the luminaire 70
(such
as cables or stems 74) may engage clips 73 to suspend the pendant luminaire 70
from the ceiling. Obviously, one of skill in the art will understand that a
variety of
different mechanical structures may be used to suspend the luminaire 70.
Because the light engines 10 and base housings 52 of each of the wall mount
50 and the pendant luminaires 70 can be identical, the manufacturer need only
manufacture one assembly of them and the supplier need only stock one such
assembly. A wall mounting kit (which would include the wall bracket 60 and the
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wall mount end caps 58) would be provided if the wall mount luminaire 50 was
requested by a purchaser. In contrast, a pendant mounting kit (which would
include clips 73, the cables or stems 74 (or other means by which to suspend
the
fixture from the ceiling), and the pendant end caps 72) would be provided if
the
pendant luminaire 70 was requested by the purchaser.
In use, light emitted from the light emitting diodes 16 in the pendant
luminaire 70 is distributed substantially outwardly from both sides of the
fixture so
as to avoid the creation of hot spots on the ceiling directly above the
luminaire but
rather widely spread the light onto the surrounding ceiling space. Different
auxiliary optical components (e.g., a diffuser) may be coupled to the
reflector 14 to
tailor the distribution into a specific architectural space to achieve smooth
uniformities typically not achievable with traditional sources. It may be
desirable,
but certainly not required, to position the diffuser 34 in the reflector 14 so
that the
diffuser 34 bows outwardly from the reflector 14. In this way, the diffuser 34
on
each side of the pendant luminaire 70 is able to direct light onto the ceiling
between
the two sides of the pendant luminaire 70 where a dark spot might appear
otherwise. In this way, the diffusers 34 help to merge the light on each side
of the
pendant luminaire 70 to create a uniform distribution of light above the
pendant
luminaire.
The distributions attained by use of the light engines 10 disclosed herein
render such light engines 10 particularly suitable for use in fixtures
positioned in
close proximity (e.g., 12 to 18 inches) to the ceiling. Such distributions
emit a far-
reaching, uniform pattern of light across the ceiling which permits wide
spacing
between adjacent luminaires (e.g., spacing from 10 to 14 feet) while
maintaining
ceiling uniformities better than 3 to 1 max to mm and maintaining high
luminaire
efficiencies typically above its florescent counterparts.
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