U.S. patent application number 11/116962 was filed with the patent office on 2005-11-24 for light emitting diode light source.
This patent application is currently assigned to OPTOLUM, INC.. Invention is credited to Dry, Joel M..
Application Number | 20050258439 11/116962 |
Document ID | / |
Family ID | 22561183 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050258439 |
Kind Code |
A1 |
Dry, Joel M. |
November 24, 2005 |
Light emitting diode light source
Abstract
A light source that utilizes light emitting diodes that emit
white light is disclosed. The diodes are mounted on an elongate
member having at least thermally conductive portions coupled
together. At least one light emitting diode is mounted on an outer
surface of the elongate member. The elongate member is thermally
conductive and is utilized to cool the light emitting diode by
transferring heat to fluid contained by said elongate member.
Inventors: |
Dry, Joel M.; (Phoenix,
AZ) |
Correspondence
Address: |
DONALD J LENKSZUS
PO BOX 3064
CAREFREE
AZ
85377
US
|
Assignee: |
OPTOLUM, INC.
Scottsdale
AZ
|
Family ID: |
22561183 |
Appl. No.: |
11/116962 |
Filed: |
April 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11116962 |
Apr 27, 2005 |
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10430696 |
May 5, 2003 |
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10430696 |
May 5, 2003 |
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10156810 |
May 29, 2002 |
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6573536 |
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Current U.S.
Class: |
257/88 |
Current CPC
Class: |
F21V 19/001 20130101;
F21K 9/20 20160801; F21V 29/75 20150115; F21V 29/83 20150115; F21Y
2103/10 20160801; F21V 29/74 20150115; F21S 4/22 20160101; F21V
29/777 20150115; F21Y 2115/10 20160801; F21Y 2107/30 20160801; F21V
29/00 20130101; F21V 29/54 20150115; F21S 4/28 20160101 |
Class at
Publication: |
257/088 |
International
Class: |
H01L 029/18 |
Claims
What is claimed is:
1. A light source comprising: an elongate thermally conductive
member having an outer surface, said elongate thermally conductive
member comprising at least two thermally conductive portions
coupled together; a plurality of light emitting diodes carried on
said elongate member outer surface at least some of said light
emitting diodes being disposed in a first plane and others of said
light emitting diodes being disposed in a second plane not
coextensive with said first plane; and said elongate thermally
conductive member being configured to conduct heat away from said
light emitting diodes to fluid contained by said elongate thermally
conductive member.
2. A light source in accordance with claim 1, wherein: said outer
surface extends over said at least two thermally conductive
portions.
3. A light source in accordance with claim 1, wherein: said
elongate thermally conductive member comprises one or more surface
discontinuities to enhance heat dissipation
4. A light source in accordance with claim 1, wherein: said fluid
contained by said elongate thermally conductive member is a cooling
medium other than air.
5. A light source in accordance with claim 1, wherein: said
elongate thermally conductive member comprises a tube.
6. A light source in accordance with claim 5, wherein: said tube
has a cross-section in the shape of a polygon.
7. A light source in accordance with claim 5,wherein: said tube has
a cross-section having flat portions.
8. A light source in accordance with claim 1, wherein: said
elongate thermally conductive member comprises a channel.
9. A light source in accordance with claim 1, wherein: each of at
least two thermally conductive portions comprises an extrusion.
10. A light source in accordance with claim 9, wherein: each said
extrusion is an aluminum extrusion.
11. A light source in accordance with claim 1, wherein: each of
said light emitting diodes emits white light.
12. A light source in accordance with claim 1, wherein: at least
some of said light emitting diodes emit colored light.
13. A light source in accordance with claim 1, comprising: one or
more electrical conductors carried by said elongate thermally
conductive member and connected to at least one of said plurality
of light emitting diodes to supply electrical power thereto.
14. A light source comprising: an elongate thermally conductive
member having an outer surface, said elongate thermally conductive
member comprising at least two thermally conductive portions
coupled together; at least one light emitting diode carried on said
elongate member outer surface; said elongate thermally conductive
member being configured to conduct heat away from said at least one
light emitting diode.
15. A light source in accordance with claim 14, wherein: said outer
surface extends over said at least two thermally conductive
portions.
16. A light source in accordance with claim 14, wherein: said
elongate thermally conductive member comprises one or more surface
discontinuities to enhance heat dissipation
17. A light source in accordance with claim 14, wherein: said fluid
contained by said elongate thermally conductive member is a cooling
medium other than air.
18. A light source in accordance with claim 14, wherein: each of at
least two thermally conductive portions comprises an extrusion.
19. A light source in accordance with claim 18, wherein: each said
extrusion is an aluminum extrusion.
20. A light source in accordance with claim 14, comprising: one or
more electrical conductors carried by said elongate thermally
conductive member and connected to said at least one light emitting
diode to supply electrical power thereto.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of my co-pending
application Ser. No. 10/430,696 filed May 05, 2003 which is a
continuation-in-part of my co-pending application Ser. No.
10/156,810 filed May 29, 2002, now U.S. Pat. No. 6,573,536.
FIELD OF THE INVENTION
[0002] This invention pertains to lighting sources, in general, and
to a lighting source that utilizes Light Emitting Diodes (LED's),
in particular.
BACKGROUND OF THE INVENTION
[0003] LED's have many advantages as light sources. However, in the
past LED's have found application only as specialized light sources
such as for vehicle brake lights, and other vehicle related
lighting, and recently as flashlights. In these prior applications,
the LED's are typically mounted in a planar fashion in a single
plane that is disposed so as to be perpendicular to the viewing
area. Typically the LED planar array is not used to provide
illumination, but to provide signaling.
[0004] Recent attempts to provide LED light sources as sources of
illumination have been few, and generally unsatisfactory from a
general lighting standpoint.
[0005] It is highly desirable to provide a light source utilizing
LED's that provides sufficient light output so as to be used as a
general lighting source rather than as a signaling source.
[0006] One problem that has limited the use of LED's to specialty
signaling and limited general illumination sources is that LED's
typically generate significant amounts of heat. The heat is such
that unless the heat is dissipated, the LED internal temperature
will rise causing degradation or destruction of the LED.
[0007] It is therefore further desirable to provide an LED light
source that efficiently conducts heat away from the LED's.
SUMMARY OF THE INVENTION
[0008] In accordance with the principles of the invention, an
improved light source is provided. The light source includes an
elongate thermally conductive member having an outer surface. A
plurality of light emitting diodes is carried on the elongate
member outer surface. At least some of the light emitting diodes
are disposed in a first plane and others of said light emitting
diodes are disposed in a second plane not coextensive with the
first plane. Electrical conductors are carried by the elongate
thermally conductive member and are connected to the plurality of
light emitting diodes to supply electrical power thereto. The
elongate thermally conductive member conducts heat away from the
light emitting diodes to a thermally conductive fluid medium. A
cooling device is utilized to remove heat from the light emitting
diodes. In one aspect of the invention, the cooling device
comprises a fluid moving device utilized to cause the fluid medium
to flow to cause cooling of the elongate thermally conductive
member and therefore to dissipate heat from the light emitting
diodes. In another aspect of the invention, the cooling device may
be an electronic or solid state device such as a Piezoelectric
device or a device that uses the Peltier effect, known as a Peltier
device.
[0009] In the illustrative embodiment of the invention, the fluid
medium is air and the fluid moving device is an air moving
device.
[0010] In accordance with one aspect of the invention, an
illustrative embodiment of the invention utilizes light emitting
diodes that emit white light. However, other embodiments of the
invention may utilize light emitting diodes that are of different
colors to produce monochromatic light or the colors may be chosen
to produce white light or other colors.
[0011] In accordance with another aspect of the invention the
elongate thermally conductive member transfers heat from the light
emitting diodes to a medium within said elongate thermally
conductive member. In the illustrative embodiment of the invention,
the medium is air.
[0012] In accordance with another aspect of the invention, the
elongate thermally conductive member has one or more projections or
fins to enhance heat transfer to the medium. The projections or
fins may be disposed on the outer surface or inner surface of the
elongate thermally conductive member or may be disposed on both the
outer and inner surfaces.
[0013] In accordance with another aspect of the invention the
elongate thermally conductive member comprises a tube. In one
embodiment of the invention, the tube has a cross-section in the
shape of a polygon. In another embodiment of the invention, the
tube has a cross-section having flat portions.
[0014] In accordance with another embodiment of the invention, the
elongate thermally conductive member comprises a channel.
[0015] In accordance with the principles of the invention, the
elongate thermally conductive member may comprise an extrusion, and
the extrusion can be highly thermally conductive material such as
aluminum.
[0016] In one preferred embodiment of the invention the elongate
thermally conductive member is a tubular member. The tubular member
has a polygon cross-section. However, other embodiments my have a
tubular member of triangular cross-section.
[0017] In one embodiment of the invention, a flexible circuit is
carried on a surface of said elongate thermally conductive member;
the flexible circuit includes the electrical conductors.
[0018] In another aspect of the invention, the flexible circuit
comprises a plurality of apertures for receiving said plurality of
light emitting diodes. Each of the light emitting diodes is
disposed in a corresponding one of the apertures and affixed in
thermally conductive contact with said elongate thermally
conductive member.
[0019] The elongate thermally conductive member includes a thermal
transfer media disposed therein in a flow channel.
[0020] At least one clip for mounting the elongate thermally
conductive member in a fixture may be included.
BRIEF DESCRIPTION OF THE DRAWING
[0021] The invention will be better understood from a reading of
the following detailed description of a preferred embodiment of the
invention taken in conjunction with the drawing figures, in which
like reference indications identify like elements, and in
which:
[0022] FIG. 1 is a planar side view of a light source in accordance
with the principles of the invention;
[0023] FIG. 2 is a top planar view of the light source of FIG.
1;
[0024] FIG. 3 is a perspective view of the light source of FIG. 1
with mounting clips;
[0025] FIG. 4 is a planar side view of the light source of FIG. 3
showing mounting clips separated from the light source;
[0026] FIG. 5 is a top view of the light source and mounting clips
of FIG. 4;
[0027] FIG. 6 is a partial cross-section of the light source of
FIG. 1;
[0028] FIG. 7 is a top view of an alternate elongate thermally
conductive member; and
[0029] FIG. 8 is a side view of the member of FIG. 7.
DETAILED DESCRIPTION
[0030] A light source in accordance with the principles of the
invention may be used as a decorative lighting element or may be
utilized as a general illumination device. As shown in FIG. 1, a
light source 100 in accordance with the invention includes an
elongate thermally conductive member or heat sink 101. Elongate
heat sink 101 is formed of a material that provides excellent
thermal conductivity. Elongate heat sink 101 in the illustrative
embodiment of the invention is a tubular aluminum extrusion. To
improve the heat dissipative properties of light source 100,
elongate heat sink 101 is configured to provide convective heat
dissipation and cooling. As more clearly seen in FIG. 2, tubular
heat sink 101 is hollow and has an interior cavity 103 that
includes one or more surface discontinuities or heat dissipating
protrusions 105. In the illustrative embodiment the surface
discontinuities or heat dissipating protrusions 105 are triangular
shaped fins, but may take on other shapes. In yet other
embodiments, the surface discontinuities may include apertures or
blind bores either alone or in combinations with heat dissipation
protrusions. Protrusions 105 are integrally formed on the interior
of elongate heat sink 101. In the illustrative embodiment movement
of a medium 102 through elongate heat sink 101 provides cooling.
Medium 102 utilized in the illustrative embodiment is air, but may
in some applications be a fluid other than air to provide for
greater heat dissipation and cooling.
[0031] Cooling device 199 is coupled to elongate thermally
conductive member 101 to enhance cooling of the LED's. Cooling
device in one embodiment of the invention is a medium moving device
in fluid coupling with elongate thermally conductive member 101 to
enhance the movement of medium 102. Medium moving device 199 is
utilized to enhance fluid medium 102 to flow to cause cooling of
the elongate thermally conductive member and therefore to dissipate
heat from the light emitting diodes. Medium moving device 199 in a
first illustrative embodiment is a fan and may be an
electromechanical fan, electronic fan, or solid-state device such
as a piezoelectric fan. In a second embodiment of the invention,
cooling device 199 may comprise one or more solid state cooling
devices utilizing the Peltier effect, otherwise known as Peltier
devices. Although cooling device 199 is shown at one end of the
light source 100, it will be appreciated by those skilled in the
art that where solid state devices are utilized, a plurality of
solid state devices may be positioned at locations other than on an
end of the light source 100. It will also be appreciated by those
skilled in the art that solid state cooling devices such as
Piezoelectric and Peltier devices are known.
[0032] The exterior surface 107 of elongate heat sink 101 has a
plurality of Light Emitting Diodes 109 disposed thereon. Each LED
109 in the illustrative embodiment comprises a white light emitting
LED of a type that provides a high light output. Each LED 109 also
generates significant amount of heat that must be dissipated to
avoid thermal destruction of the LED. As noted above cooling device
199 provides cooling to avoid thermal destruction. By combining a
plurality of LEDs 109 on elongate thermally conductive member or
heat sink 101, a high light output light source that may be used
for general lighting is provided.
[0033] Conductive paths 129 are provided to connect LEDs 109 to an
electrical connector 111. The conductive paths may be disposed on
an electrically insulating layer 131 or layers disposed on exterior
surface 107. In the illustrative embodiment shown in the drawing
figures, the conductive paths and insulating layer are provided by
means of one or more flexible printed circuits 113 that are
permanently disposed on surface 107. As more easily seen in FIG. 6,
printed circuit 113 includes an electrically insulating layer 131
that carries conductive paths 129. As will be appreciated by those
skilled in the art, other means of providing the electrically
conductive paths may be provided.
[0034] Flexible printed circuit 113 has LED's 109 mounted to it in
a variety of orientations ranging from 360 degrees to 180 degrees
and possibly others depending on the application. Electrical
connector 111 is disposed at one end of printed circuit 113.
Connector 113 is coupleable to a separate power supply to receive
electrical current. Flexible printed circuit 113, in the
illustrative embodiment is coated with a non-electrically
conductive epoxy that may be infused with optically reflective
materials. Flexible printed circuit 113 is adhered to the tube 101
with a heat conducting epoxy to aid in the transmission of the heat
from LEDs 109 to tube 101. Flexible printed circuit 113 has
mounting holes 134 for receiving LEDs 109 such that the backs of
LEDs 109 are in thermal contact with the tube surface 107.
[0035] Tubular heat sink 101 in the illustrative embodiment is
formed in the shape of a polygon and may have any number of sides.
Although tubular heat sink 101 in the illustrative embodiment is
extruded aluminum, tubular heat sink 101may comprise other thermal
conductive material. Fins 105 may vary in number and location
depending on particular LED layouts and wattage. In some instances,
heat dissipation protrusions or fins may be added to the exterior
surface of tubular heat sink 101. In addition, apertures may be
added to the tubular heat sink to enhance heat flow.
[0036] FIGS. 7 and 8 show an alternate elongate thermally
conductive member 201 that has both exterior surface
discontinuities or heat dissipation protrusions or fins 205 in
addition to interior surface discontinuities or heat dissipation
protrusions or fins 241.
[0037] Light source 100 is mounted into a fixture and retained in
position by mounting clips 121,123 as most clearly seen in FIGS. 3,
4, and 5. Each of the clips is shaped so as to engage and retain
light source 100. Each clip is affixed on one surface 122, 124 to a
light fixture.
[0038] Although light source 100 is shown as comprising elongate
tubular thermally conductive members or heat sinks 101, 201, other
extruded elongate members may be used such as channels.
[0039] In the illustrative embodiment shown, cooling by flow of air
through elongate thermally conductive members or tubular heat sinks
101, 201 is utilized such that cool or unheated air enters elongate
thermally conductive members 101, 201 by fluid movement device 199,
passes over the surface discontinuities or heat dissipation
protrusions, and exits from the opposite end of elongate thermally
conductive member 101, 201 as heated air. In higher wattage light
sources, rather than utilizing air as the cooling medium, other
fluids may be utilized. In particular, convective heat pumping may
be used to remove heat from the interior of the heat sink.
[0040] In one particularly advantageous embodiment of the
invention, the light source of the invention is configured to
replace compact fluorescent lighting in decorative
applications.
[0041] It will be appreciated by those skilled in the art that
although the invention has been described in terms of light
emitting diodes, the invention is equally applicable to other
non-filament miniature lights sources such as organic light
emitting diodes (OLED's) and polymer type light sources. It is
intended that the term "light emitting diode" or "LED" as used in
the claims is intended to not be limited to solid state light
emitting diodes, but is intended to include such other miniature
light sources.
[0042] It has further been determined that the uniformity of light
distribution of a light source having an elongate thermally
conductive member with heat dissipation protrusions or fins 205 on
the outer surface of the elongate thermally conductive member 201
is enhanced by utilization of an appropriately selected coating or
treatment to the outer or exterior surfaces of elongate thermally
conductive member 201. In particular, in a comparison of various
surface coatings or treatments, it has been found that the use of a
non-reflective or black surface on the protrusions or fins 205
provides a more uniform light output. It has been determined that
the use of reflective or white surfaces on protrusions results in
the protrusions producing shadows in the light output.
[0043] As will be appreciated by those skilled in the art, the
principles of the invention are not limited to the use of light
emitting diodes that emit white light. Different colored light
emitting diodes may be used to produce monochromatic light or to
produce light that is the combination of different colors.
[0044] Although the invention has been described in terms of
illustrative embodiments, it is not intended that the invention be
limited to the illustrative embodiments shown and described. It
will be apparent to those skilled in the art that various changes
and modifications may be made to the embodiments shown and
described without departing from the spirit or scope of the
invention. It is intended that the invention be limited only by the
claims appended hereto.
* * * * *