U.S. patent application number 14/398944 was filed with the patent office on 2015-04-30 for lamp with heat sink and active cooling device.
The applicant listed for this patent is Stevn DARBIN, GE LIGHTING SOLUTIONS, LLC, Daniel Grimm, Lee JONES, Jeffrey Kelley, Raghav Mahalingham, Andrew POYNOT, Randall Williams. Invention is credited to Steven Darbin, Daniel Grimm, Lee Jones, Jeffrey Kelley, Glenn Howard Kuenzler, Raghav Mahalingham, Jeremias Anthony Martins, Andrew Poynot, Anthony Michael Rotella, Randall Williams.
Application Number | 20150117019 14/398944 |
Document ID | / |
Family ID | 48446663 |
Filed Date | 2015-04-30 |
United States Patent
Application |
20150117019 |
Kind Code |
A1 |
Kuenzler; Glenn Howard ; et
al. |
April 30, 2015 |
LAMP WITH HEAT SINK AND ACTIVE COOLING DEVICE
Abstract
A lamp comprising a light source comprising at least one solid
state emitter. The lamp comprises a heat sink body in thermal
communication with said light source. At least one air flow nozzle
is present in the lamp to direct air flow across at least a portion
of the heat sink body. The lamp further comprises an active cooling
device, in which the active cooling device is in fluid
communication with the at least one air flow nozzle and is
configured to provide a flow of air to the at least one air flow
nozzle. The lamp further comprises driver electronics configured to
provide power to each of the light source and the active cooling
device, wherein the driver electronics are remote from the active
cooling device.
Inventors: |
Kuenzler; Glenn Howard;
(Beachwood, OH) ; Martins; Jeremias Anthony;
(Twinsburgh, OH) ; Rotella; Anthony Michael;
(Cleveland, OH) ; Darbin; Steven; (Austin, TX)
; Jones; Lee; (Austin, TX) ; Poynot; Andrew;
(Austin, TX) ; Mahalingham; Raghav; (Austin,
TX) ; Grimm; Daniel; (Austin, TX) ; Williams;
Randall; (Austin, TX) ; Kelley; Jeffrey;
(Austin, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DARBIN; Stevn
JONES; Lee
POYNOT; Andrew
Mahalingham; Raghav
Grimm; Daniel
Williams; Randall
Kelley; Jeffrey
GE LIGHTING SOLUTIONS, LLC |
Austin
Austin
Austin
Austin
Austin
Austin
Austin
East Cleveland |
TX
TX
TX
TX
TX
TX
TX
OH |
US
US
US
US
US
US
US
US |
|
|
Family ID: |
48446663 |
Appl. No.: |
14/398944 |
Filed: |
May 3, 2013 |
PCT Filed: |
May 3, 2013 |
PCT NO: |
PCT/US2013/039513 |
371 Date: |
November 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61643056 |
May 4, 2012 |
|
|
|
Current U.S.
Class: |
362/294 ;
362/373 |
Current CPC
Class: |
Y02B 20/30 20130101;
F21V 3/02 20130101; F21V 7/28 20180201; F21V 13/08 20130101; F21Y
2113/13 20160801; F21V 7/0091 20130101; F21V 7/048 20130101; F21V
29/74 20150115; F21V 7/041 20130101; F21Y 2105/00 20130101; F21V
29/63 20150115; F21V 29/70 20150115; F21Y 2115/15 20160801; G02B
27/0972 20130101; F21V 29/67 20150115; F21V 29/83 20150115; F21Y
2105/10 20160801; F21V 29/507 20150115; F21V 29/75 20150115; F21K
9/232 20160801; F21V 29/87 20150115; F21K 9/60 20160801; F21Y
2115/10 20160801; F21V 29/60 20150115; F21V 23/009 20130101; F21V
29/773 20150115; F21K 9/238 20160801 |
Class at
Publication: |
362/294 ;
362/373 |
International
Class: |
F21V 29/60 20060101
F21V029/60; F21V 29/67 20060101 F21V029/67; F21V 29/75 20060101
F21V029/75; F21V 29/70 20060101 F21V029/70 |
Claims
1. A lamp comprising: a light source comprising at least one solid
state emitter; a heat sink body in thermal communication with the
light source; at least one air flow nozzle to direct air flow
across at least a portion of the heat sink body; an active cooling
device, wherein the active cooling device is in fluid communication
with the at least one air flow nozzle and is configured to provide
a flow of air to the at least one air flow nozzle; and driver
electronics configured to provide power to each of the light source
and the active cooling device, and remote from the active cooling
device.
2. The lamp in accordance with claim 1, wherein the at least one
active cooling device comprises at least one of synthetic jet, fan
or piezojet.
3. The lamp in accordance with claim 1, wherein the lamp further
comprises one or more optical element for distributing light,
wherein the one or more optical element is configured to provide a
substantially uniform omnidirectional light distribution from the
lamp when the lamp is in operation.
4. The lamp in accordance with claim 1, wherein the lamp comprises
a geometric configuration which substantially conforms to the ANSI
A19 volumetric profile.
5. The lamp in accordance with claim 1, wherein the lamp is
configured to operate on a power level greater than 15 W of input
power and possesses sufficient cooling ability for an efficiency of
at least 60 LPW when the lamp is in operation.
6. The lamp in accordance with claim 1, wherein the heat sink body
comprises a cavity, and the active cooling device is disposed at
least partially within the cavity, and wherein the driver
electronics are not disposed at least partially within the
cavity.
7. The lamp in accordance with claim 1, wherein the at least one
air flow nozzle is formed as an aperture in, or is integral to, the
heat sink body.
8. The lamp in accordance with claim 1, wherein the heat sink body
further comprises a plurality of fins, wherein the plurality of
fins comprise a first set of fins of a relatively greater axial
length and a second set of fins of a relatively lesser axial
length.
9. The lamp in accordance with claim 8, wherein at least the second
set of fins do not block light emitted from the lamp, or are in the
shadow of the lamp.
10. The lamp in accordance with claim 1, wherein the at least one
air flow nozzle comprises an air flow divider internal to the
nozzle.
11. The lamp in accordance with claim 10, wherein the air flow
divider comprises a blade edge or ship-hull shape.
12. The lamp in accordance with claim 1, wherein a flow of air to
the at least one nozzle is caused to turn at an angle of 90.degree.
or greater, and wherein the flow of air which is caused to turn
traverses a rounded surface.
13. The lamp in accordance with claim 1, wherein air flow from the
at least one nozzle, when the lamp is in operation, is
characterized by a value for Re(d) of about 50 to about 800.
14. The lamp in accordance with claim 1, wherein the heat sink
comprises a plurality of fins, wherein the at least one air flow
nozzle is proximate to a selected fin, and wherein, when the lamp
is in operation, the air flow along the selected fin is
characterized by a value for Re(FL) of about 500 to about
13000.
15. The lamp in accordance with claim 1, wherein the lamp possesses
sufficient cooling ability for an efficiency of at least 60 LPW
when in operation and/or an L70 lifetime of at least about 25000
hours.
16. (canceled)
17. (canceled)
18. A lamp comprising: a light source comprising at least one solid
state emitter; a heat sink body in thermal communication light
source, the heat sink body further comprising a plurality of fins,
wherein a majority of the plurality of fins are in a shadow area of
the lamp; at least one air flow nozzle to direct air flow across at
least a portion of the heat sink body; an active cooling device,
wherein the active cooling device is in fluid communication with
the at least one air flow nozzle and is configured to provide a
flow of air to the at least one air flow nozzle; and driver
electronics configured to provide power to each of the light source
and the active cooling device, and optionally remote from the
active cooling device.
19. The lamp in accordance with claim 1, further comprising: a
housing, wherein a surface of the housing and a surface of the heat
sink body form the at least one air flow nozzle.
20. The lamp in accordance with claim 19, wherein a boundary of the
at least one nozzle is defined by both a surface of the housing and
a surface of a heat sink.
21. A lamp comprising: a light source comprising at least one solid
state emitter; a heat sink body in thermal communication with the
light source, the heat sink body further comprising at least one
fin having two lateral sides; at least one air flow nozzle to
direct air flow across at least a portion of the heat sink body; an
active cooling device, wherein the active cooling device is in
fluid communication with the at least one air flow nozzle, and the
active cooling device is configured to provide a flow of air to the
at least one air flow nozzle; wherein air is axially directed
adjacent both lateral sides of the at least one fin; and driver
electronics configured to provide power to each of the light source
and the active cooling device, and optionally remote from the
active cooling device.
22. The lamp in accordance with claim 21, wherein at least two air
flow nozzles are positioned adjacent an end of the at least one fin
to direct air in an axial direction adjacent both lateral sides of
the at least one fin.
23. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to, and the benefit of,
Provisional Patent Application Ser. No. 61/643,056 filed on May 4,
2012, the disclosure of which is incorporated herein by reference
in its entirety.
BACKGROUND
[0002] The subject matter of the present disclosure relates
generally to a lamp having an active cooling device that provides
air flow over a heat sink to cool the lamp.
[0003] Lamps based on solid state light emitting sources, such as
light-emitting diode (LED)-based lamps, typically require operation
at relatively low temperatures for device performance and
reliability reasons. For example, the junction temperature for a
typical LED device should be below 150.degree. C., and in some LED
devices should be below 100.degree. C. or even lower. At these low
operating temperatures, the radiative heat transfer pathway to the
ambient is weak compared with that of conventional light sources.
In LED light sources, the convective and radiative heat transfer
from the outside surface area of the lamp or luminaire can both be
enhanced by the addition of a heat sink. A heat sink is a component
providing a large surface for radiating and convecting heat away
from the LED devices. In a typical design, the heat sink is a
relatively massive metal element having a large engineered surface
area, for example by having fins or other heat dissipating
structures on its outer surface. The large mass of the heat sink
efficiently conducts heat from the LED devices to the heat fins,
and the large area of the heat fins provides efficient heat egress
by radiation and convection. For high power LED-based lamps it is
also known to employ active cooling using fans or heat pipes or
thermo-electric coolers or pumped coolant fluid to enhance the heat
removal.
[0004] However, there remains a need to devise systems for
efficient removal of heat from high power LED-based lamps, for high
efficiency.
SUMMARY
[0005] In one aspect of embodiments of the invention, is provided a
lamp comprising a light source comprising at least one solid state
emitter. The lamp comprises a heat sink body in thermal
communication with said light source. At least one air flow nozzle
is present in the lamp to direct air flow across at least a portion
of the heat sink body. The lamp further comprises an active cooling
device, in which the active cooling device is in fluid
communication with the at least one air flow nozzle and is
configured to provide a flow of air to the at least one air flow
nozzle. The lamp further comprises driver electronics configured to
provide power to each of the light source and the active cooling
device, wherein the driver electronics are remote from the active
cooling device.
[0006] In another aspect of embodiments of the invention is
provided a lamp, comprising a light source comprising at least one
solid state emitter and a heat sink body in thermal communication
with said light source, and having at least one air flow nozzle to
direct air flow across at least a portion of the heat sink body.
The at least one air flow nozzle is formed as an aperture in the
heat sink body. The lamp further comprises an active cooling
device, wherein the active cooling device is in fluid communication
with the at least one air flow nozzle and is configured to provide
a flow of air to the at least one air flow nozzle. The lamp further
comprises driver electronics configured to provide power to each of
the light source and the active cooling device, which driver
electronics may be remote from the active cooling device.
[0007] In another aspect of embodiments of the invention is
provided a lamp comprising a light source comprising at least one
solid state emitter, and a heat sink body in thermal communication
with the light source. The heat sink body further comprises a
plurality of fins, wherein the plurality of fins comprise a first
set of fins of a relatively greater axial length and a second set
of fins of a relatively lesser axial length, wherein the axis may
be generally parallel with a longitudinal axis of the lamp. The
lamp further comprises at least one air flow nozzle to direct air
flow across at least a portion of the heat sink body, and an active
cooling device, wherein the active cooling device is in fluid
communication with the at least one air flow nozzle and is
configured to provide a flow of air to the at least one air flow
nozzle. The lamp further comprises driver electronics configured to
provide power to each of the light source and the active cooling
device, and the driver electronics may be remote from the active
cooling device.
[0008] In another aspect of an embodiment of the invention, is
provided a lamp comprising a light source comprising at least one
solid state emitter, and a heat sink body in thermal communication
with the light source. The heat sink body further comprises a
plurality of fins, wherein a majority of the plurality of fins are
in a shadow area of the lamp. The lamp comprises at least one air
flow nozzle to direct air flow across at least a portion of the
heat sink body, and an active cooling device, wherein the active
cooling device is in fluid communication with the at least one air
flow nozzle and is configured to provide a flow of air to the at
least one air flow nozzle. The lamp further comprises driver
electronics configured to provide power to each of the light source
and the active cooling device, which driver electronics may be
remote from the active cooling device.
[0009] In another aspect of an embodiment of the invention, is
provided a lamp comprising a light source comprising at least one
solid state emitter, and a heat sink body, the heat sink body in
thermal communication with the light source. The lamp further
includes at least one air flow nozzle configured to direct air flow
across at least a portion of the heat sink body, and an active
cooling device in fluid communication with the at least one air
flow nozzle, which cooling device is configured to provide a flow
of air to the at least one air flow nozzle. The lamp further
comprises a housing. A surface of the housing and a surface of the
heat sink body form the at least one air flow nozzle. The lamp
further comprises driver electronics configured to provide power to
each of the light source and the active cooling device, which
driver electronics may be remote from the active cooling
device.
[0010] In another aspect of embodiments of the invention, is
provided a lamp comprising a light source comprising at least one
solid state emitter, and a heat sink body in thermal communication
with the light source. The heat sink body further comprises at
least one fin having two lateral sides. The lamp includes at least
one air flow nozzle to direct air flow across at least a portion of
the heat sink body, and an active cooling device in fluid
communication with the at least one air flow nozzle. The active
cooling device is configured to provide a flow of air to the at
least one air flow nozzle. In operation of the lamp, air is axially
directed adjacent both lateral sides of the at least one fin. The
lamp further comprises driver electronics configured to provide
power to each of the light source and the active cooling device,
which driver electronics may be remote from the active cooling
device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth in the specification, which makes
reference to the appended figures, in which:
[0012] FIG. 1 is a perspective view of a lamp of a first specific
embodiment.
[0013] FIG. 2 is a front view of a lamp of a first specific
embodiment.
[0014] FIG. 3 is a top view of a lamp of a first specific
embodiment.
[0015] FIG. 4 is a sectional view of a lamp of a first specific
embodiment.
[0016] FIG. 5 is a sectional view of a heat sink and active cooling
device of a first specific embodiment.
[0017] FIG. 6 is a sectional view of a heat sink of a first
specific embodiment.
[0018] FIG. 7 is a sectional view showing cooling air flow,
according to a first specific embodiment.
[0019] FIG. 8 is another a sectional view showing cooling air flow,
according to a first specific embodiment.
[0020] FIG. 9 is a perspective view of a lamp of a second specific
embodiment.
[0021] FIG. 10 is a cutaway view of components of a lamp of a
second specific embodiment.
[0022] FIG. 11 is another cutaway view of components of a lamp of a
second specific embodiment.
[0023] FIG. 12 is a transparent sectional view of components of a
lamp of a second specific embodiment.
[0024] FIG. 13 is a perspective view of a lamp of a third specific
embodiment.
[0025] FIG. 14 is a sectional view of a lamp of a third specific
embodiment.
[0026] FIG. 15 shows air flow through a heat sink in accordance
with a third specific embodiment.
[0027] FIG. 16 is a front view of a lamp in accordance with a
fourth specific embodiment.
[0028] FIG. 17 is a sectional view of a lamp in accordance with a
fourth specific embodiment.
[0029] FIG. 18 is a front view of a lamp in accordance with a fifth
specific embodiment.
[0030] FIG. 19 is a cutaway front view of a lamp in accordance with
a fifth specific embodiment.
[0031] FIG. 20 is a top transparent view of a lamp in accordance
with a fifth specific embodiment.
[0032] FIG. 21 is a side closeup view of the cooperation of a fin
and nozzle of a lamp in accordance with a fifth specific
embodiment.
[0033] FIG. 22 is an view of the interior of a nozzle showing a
diverter.
[0034] FIG. 23 is a sectional view showing air flow from a nozzle
of a lamp in accordance with a fifth specific embodiment.
[0035] FIG. 24 is an exploded view of a lamp in accordance with a
fifth specific embodiment.
[0036] FIG. 25 is a side view of a lamp in accordance with a sixth
specific embodiment.
[0037] FIG. 26 is a transparent side view of a lamp in accordance
with a sixth specific embodiment, exposing an active cooler.
[0038] FIG. 27 is a side view of a heat sink employed in a lamp in
accordance with a sixth specific embodiment.
[0039] FIG. 28 is a perspective view of a heat sink employed in a
lamp in accordance with a sixth specific embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0040] As noted, embodiments of the invention provide a lamp,
comprising a light source comprising at least one solid state
emitter, and a heat sink body in thermal communication with the
light source. The lamp includes at least one air flow nozzle to
direct air flow across at least a portion of said the sink body,
and an active cooling device, wherein the active cooling device is
in fluid communication with the at least one air flow nozzle and is
configured to provide a flow of air to the at least one air flow
nozzle. The lamp further includes driver electronics configured to
provide power to each of the light source and the active cooling
device, and the driver electronics may be remote from the active
cooling device.
[0041] As used herein, the term "lamp" may be taken as being
generally equivalent to any of the following alternative
phraseology: "lighting device"; "lighting apparatus";
"light-emitting apparatus"; "illumination device". A "light source
comprising at least one solid state emitter" typically may comprise
an LED-based light engine such as an array of LED chips or dies; a
"lamp" includes further components in addition to this light
source, such as optical elements for distribution of emitted light,
a heat sink body for thermal management, and an active cooling
device for generating a flow of cooling fluid such as air. It is to
be understood that "air" may be replaced by any fluid which is
suitable for heat dissipation.
[0042] In accordance with embodiments of the invention, a heat sink
body (and any attendant heat dissipating surface area enhancing
structures, e.g., fins) may comprise one or more high thermal
conductivity materials. A high conductivity material will allow
more heat to move from the thermal load to ambient and result in a
reduction in temperature rise of the thermal load. Exemplary
materials can include metallic materials such as alloy steel, cast
aluminum, extruded aluminum, and copper; or the like. Other
materials can include engineered composite materials such as
thermally-conductive polymers as well as plastics, plastic
composites, ceramics, ceramic composite materials, nano-materials,
such as carbon nanotubes (CNT) or CNT composites. Other
configurations may include a plastic heat sink body comprising a
thermally conductive (e.g., copper) layer disposed thereupon, such
as disclosed in US Patent Publication 2011-0242816, hereby
incorporated by reference. Exemplary materials can exhibit thermal
conductivities of about 50 W/m-K, from about 80 W/m-K to about 100
W/m-K, 170 W/m-K, 390 W/m-K, and from about 1 W/m-K to about 50
W/m-K, respectively. In order to maximize light output, a heat sink
body and/or fin may comprise a reflective layer, such as a
reflective layer which has a reflectivity for visible light of
greater than about 90%. Reflective heat sinks which may be employed
are those described and enabled in US Patent Publication
2012-0080699, which is hereby incorporated by reference.
[0043] In accordance with embodiments of this disclosure, any heat
sink body and/or heat sink fin and/or heat sink finlet may
individually comprise a metallic material or generally, any
material having an effective thermal conductivity. For example, a
heat sink may comprise regions of differing thermal conductivity.
For example, it may be attractive to seat an array of LED chips on
a board, on a region (e.g., a copper slug) comprising copper metal
(for its very high thermal conductivity), and the region comprising
copper metal is affixed to an aluminum heat sink (for its
acceptable thermal conductivity and acceptable cost).
[0044] The heat sink body of lamps in accordance with embodiment of
this invention will be in thermal communication with at least the
light source. This is for the purpose of transferring heat energy
from the light source to the heat sink body during operation of
lamp, so that the LEDs may operate efficiently. The phrase "thermal
communication" generally refers to heat transfer that occurs
between (or among) the two (or more) items that are in thermal
communication, regardless of how the heat is transferred between or
among the items (e.g., conduction, convection, radiation, or any
combinations thereof, directly or indirectly). In some
situations/embodiments, the majority of the heat transferred from
solid state light emitters is transferred to a heat sink body by
conduction; in other situations/embodiments, the majority of the
heat may be transferred by convection, or a combination of
conduction and convection.
[0045] In accordance with embodiments of this disclosure, the at
least one active cooling device may comprise at least one of
synthetic jet, fan or piezojet; or the like. As would be generally
understood by persons skilled in the art, a synthetic jet typically
provides an oscillating air flow which may efficiently and
effectively direct relatively cooler air from the ambient, towards
the proximity of a heat sink body and/or fins, so as to carry heat
away from the lamp. Many synthetic jet actuators/active cooling
devices which are described in Provisional Patent Application Ser.
No. 61/643,056 filed on May 4, 2012 (the disclosure of which is
incorporated herein by reference in its entirety), may be
employed.
[0046] In general, any active cooling device of the present
disclosure (such as a synthetic jet or synthetic jet actuator) may
be characterized by its efficiency expressed in terms of flow rate
of air from the cooling device, per watt of power input to the
cooling device. The flow rate of air is the volume of air displaced
by the movement of the diaphragms of the cooling device, per unit
time (but volume of air here typically does not include the volume
of any entrained air). In accordance with some embodiments, the
cooling device comprises a synthetic jet operating at less than
about six cubic feet per minute (CFM) per watt. "Watts of input
power" for this purpose, only refers to the power consumption of
the cooling device itself, not necessarily the power required to
operate a lamp as a whole. In other, narrower embodiments, a
cooling device of the present disclosure may be characterized by an
efficiency of less than about 4 CFM/W (e.g., 1-4 CFM/W), or less
than about 2 CFM/W, or about 1 CFM/W. By configuring a cooling
device for such efficiency values, one may achieve lower cost,
through using fewer and/or less expensive permanent magnet(s).
[0047] Nozzles generally permit air to be alternately taken in by a
synthetic jet, and then propelled from the synthetic jet, depending
upon which cycle of the "breathing" mode of operation this type of
active cooling device is operating. In some embodiments, at least
one air flow nozzle is formed as an aperture in, or is integral to,
the heat sink body. In some embodiments, at least one air flow
nozzle comprises an air flow divider which is internal to the
nozzle. Such air flow divider may comprise a wall effective to
divide a flow of air, yet usually without creation of significant
acoustic noise when air is flowing past the divider. In certain
embodiments, such air flow divider comprises a blade edge or
ship-hull shape.
[0048] In certain embodiments, the heat sink body may further
comprise a plurality of heat dissipating surface area enhancing
structures such as fins (e.g., thermal fins). These may be made of
the same or different material than the heat sink body. In some
embodiments of the present disclosure, the plurality of heat
dissipating surface area enhancing structures comprise a first set
of fins of a relatively greater axial length and a second set of
fins of a relatively lesser axial length. That is, if a lamp
defines a generally longitudinal profile, there will be a geometric
axis to the lamp, and the two respective sets of fins are disposed
generally parallel to the axis. Their respective lengths measured
along the axial direction, may be different, as above. Where such
second set of fins are employed, they generally are disposed such
that they do not block light emitted from the lamp, or are in the
shadow of the lamp. That is, these shorter "finlets" may enhance
heat dissipation from the lamp while minimizing obstruction of
emitted light. As a general design principle, the number, size and
shape, and geometric configuration of the fins in the lamp are
selected to optimize high convective heat transfer with low
obstruction of light when the lamp is in operation.
[0049] In some embodiments, and independent of the presence of
finlets, at least some or a majority of the plurality of heat
dissipating surface area enhancing structures do not block light
emitted from the lamp, or are in the shadow of the lamp.
[0050] With respect to the air flow employed in many embodiments of
actively cooled lamp described herein, the air flow should
generally comprise a Reynolds number (as defined below) which is
selected to optimize high/maximum convective cooling with
low/minimum noise from the air flow. Air flow may be selected to be
turbulent, laminar, or combination thereof.
[0051] In selected embodiments, air flow from the at least one
nozzle (when the lamp is in operation), comprises a Reynolds number
Re at peak air flow velocity selected to optimize high/maximum
convective cooling with low/minimum noise from the air flow. For
example, the air flow from the at least one nozzle may be
characterized by a value for Re(d) (defined below) of from about 50
to about 800, or more narrowly, from about 100 to about 350.
[0052] Inventors of the present specification has found that
specified flow parameters (such as Re) for air flowing from a
nozzle in an actively cooled lamp can have important technical
effects. Air flow from a nozzle with a Re value which is too high
will generally result in an unacceptable acoustic noise level,
while too low a value for Re typically results in insufficient
cooling of an actively cooled lamp. Therefore, investigations by
the present inventors have ascertained preferred parameters,
described as follows.
[0053] As would be understood by the persons of ordinary skill in
the art, Reynolds numbers for air can be calculated by a product of
the fluid velocity (U), a characteristic length (L.sub.char), and
the inverse of a fluid kinematic viscosity (v):
Re=(U*L.sub.char)/v.
[0054] For an actively cooled lamp having an active cooling device
(e.g., a synthetic jet), it may sometimes be convenient to
determine fluid velocity U as a ratio of the volume flow rate Q for
air from the synthetic jet, to the number of nozzles times the
total area of the nozzle openings.
[0055] Note that for air as a cooling fluid, many relevant
parameters (e.g., viscosity) are known. Thus, all that is
reasonably needed to measure to obtain a Re value, is the
characteristic length and the fluid velocity (U). The velocity is
generally measured at the egress of the relevant nozzle. However,
since the velocity of air ejected from a given nozzle may be
continuously changing (e.g., in a sinusoidal manner due to the
cyclic behavior of a synthetic jet), this disclosure will define
peak velocity (the maximum velocity with respect to space and with
respect to time) as the relevant fluid velocity U. Peak velocity
can be measured by any effective means, as would be understood by
the artisan of ordinary skill, including many known means such as
hotwire anemometer, or by calculation.
[0056] The characteristic length (L.sub.char) is defined as either
the hydraulic diameter (d) of a given nozzle; or, alternatively,
L.sub.char is a distance (FL) from a nozzle exit to the furthest
extent of an adjacent heat dissipating structure along which the
air flows after leaving the nozzle. In one example, a heat
dissipating structure is a fin which is proximate to a nozzle, and
so therefore, FL would be measured as a distance from the nozzle to
the point of the fin (e.g., its far tip) which is most distal from
the nozzle. In other examples, the heat dissipating structure may
have other configurations, e.g., tubes, pins, walls, prongs, etc.
Regardless, FL is distance from opening of nozzle to most distal
point of the heat dissipating structure relative to the nozzle.
[0057] Note that FL is not necessarily the length of a heat
dissipating structure itself; if a heat dissipating structure is
spaced apart from a nozzle, FL will be the sum of the length of the
heat dissipating structure and the distance of the heat dissipating
structure from the nozzle. In either event, FL is a characteristic
length pertaining to the distance air flow travels along a heat
dissipating structure when ejected from a nozzle. Since there are
two different types of characteristic lengths, there are two
different Reynolds numbers which are relevant to this disclosure:
Re(d) and Re(FL). The value for Re(d) is the Reynolds number using
the hydraulic diameter (d) of a given nozzle as the characteristic
length; and the value for Re(FL) is the Reynolds number using FL as
the characteristic length.
[0058] Now that the two different types of Reynolds numbers
(namely, Re(d) and Re(FL)) have been defined, certain lamp
embodiments with selected values of Re(FL) are now described.
Re(FL) depends upon the use of a heat dissipating surface area
enhancing structure, such as a fin. Therefore, in some embodiments,
the heat sink body comprises a plurality of heat dissipating
surface area enhancing structures, wherein the at least one air
flow nozzle is proximate to a selected heat dissipating surface
area enhancing structure. In such embodiment (when the lamp is in
operation), the air flow along the selected heat dissipating
structure is characterized by a value for Re(FL) of from about 500
to about 13000, or more narrowly, from about 1200 to about 6400. In
such embodiment, the lamp may further exhibit values (when in
operation) for Re(d) of from about 50 to about 800.
[0059] Importantly, embodiments of the present invention may be
capable of achieving a noise level of about 20 dBA or less (e.g.,
from about 16 dBA to about 20 dBA, or from about 16 dBA to about 17
dBA), when an actively cooled lamp is driven at a power of about 27
W. Noise levels are generally measured in terms of sound pressure
at an observer distance of 1 meter. One technical effect for the
selection of the above-noted Reynolds numbers may include these
values for acoustic noise. Another technical effect may include
enhanced cooling of the lamp.
[0060] In certain embodiments, the above noted ranges for Re(d) and
Re(FL) are taken as being relevant to actively cooled lamps having
lumen output equal to or greater than 1600 lumens and conforming to
the ANSI A19 profile; however, these ranges should not be construed
as limited to such type of actively cooled lamp.
[0061] In accordance with some embodiments, other measures may be
taken to reduce acoustic noise. In one embodiment, the lamp may
comprise a heat sink body which comprises at least one curved lower
edge adapted to allow air to flow around such edge with reduced air
flow noise. As a general design principle, it is preferable that
air flow, especially "turned" air flow, substantially does not turn
around a sharp edge; or stated differently, any turned air flow
substantially always turns around a rounded edge. Therefore, in
accordance with some embodiments, a flow of air to the at least one
nozzle is caused to turn at an angle of 90.degree. or greater,
wherein this turned flow of air passes or traverses rounded edges
or rounded surfaces. For example, a flow of air which is caused to
turn at an angle of 90.degree. or greater, only encounters a
rounded surface of the lamp when it is being turned. Specifically,
heat sink body and/or housing may typically be configured such that
whenever air is turned (e.g., in any angle>90.degree.), it
should be made to flow around at least some rounded edges; for
example, whenever air must turn in direction around an angle of
>90.degree., substantially no edges which are traversed or
passed are sharp edges. Although not limited by the following
theory, it is believed that rounded edges contribute to reduced
acoustic noise reduction by avoiding the formation of vortices. In
embodiments of the disclosure, air is generally guided gently
around turns; in contrast, if air is guided around sharp edges, a
vortex may be created which can contribute to acoustic noise.
[0062] The driver electronics of the lamp (e.g., electronic
driver(s) and controller(s) such as ASIC) typically are dedicated
to driving and providing the proper electrical signals for both the
one or more light sources (such as array of LED dies), and for the
active cooling device. Driver electronics may typically comprise a
light emitting diode (LED) power supply and a synthetic jet power
supply on a single circuit board (e.g., PCB). The active cooling
device may be further configured to direct an air flow for cooling
the driver electronics.
[0063] In many embodiments, the driver electronics of a lamp are in
a location remote from the active cooling device. For example, if
an active cooling device such as a synthetic jet assembly is at
least partially enclosed by a heat sink body, the driver
electronics for the active cooling device may be in a separate
driver housing. In other words, the heat sink body may comprise a
cavity, such as an inverted cup-shaped cavity, and the active
cooling device may be disposed at least partially within this
cavity, but the driver electronics generally are not disposed at
least partially within this cavity. In general, the active cooling
device typically does not have its associated circuitry (e.g.,
ASIC) in the same enclosure with the active cooling device. This
may have the technical effect of allowing for miniaturization of
the active cooling device. A smaller active cooling device, e.g., a
smaller synthetic jet assembly than those heretofore available, may
allow a lamp to substantially fit within the ANSI A19 volumetric
profile.
[0064] In some embodiments, a lamp may comprise a geometric
configuration which substantially conforms to the ANSI A19
volumetric profile, while being configured to operate on a power
level greater than 15 W of input power and possessing sufficient
cooling ability for an efficiency of at least 60 LPW when the lamp
is in operation. In many embodiments, a lamp of the present
invention, when in operation, may be capable of providing a lumen
output of 1600 lumens or greater (e.g., greater than 1700 lumens),
when operating on a power level greater than 15 W (e.g., greater
than 20 W) of input power. These parameters are technical features
of many of the embodiments of the invention, such as those
described hereinbelow. However, embodiments of the invention and
the principles of its design and operation are not limited to the
A19 lamp envelope. Rather, they are applicable to all suitable lamp
profiles globally. Illustratively, such lamp envelopes may include:
A series (e.g., A19), B series, C-7/F series, G series, P-25/PS-35
series, BR series, R series, RP-11/S series, PAR series, T series,
and MR-n series.
[0065] As would be understood by persons of skill in the art, it is
usual for a lamp based upon solid state light emitting sources to
have a lifetime measured as "L70", which refers to a number of
operational hours in which the light output of the lamp does not
degrade by more than 30%. Therefore, embodiments of the present
disclosure may provide an expected L70 lifetime of at least about
25000 hours, preferably up to about 50000 hours.
[0066] Typically, a lamp may include a driver housing which can be
constructed e.g., from a plastic material, which facilitates the
manufacture of features such as air flow nozzles, if present in
this driver housing. A driver housing may be connected with a base
(e.g, an Edison base) that may include threads for connection into
a conventional socket to provide electrical power to operate lamp.
Other constructions may also be employed for connecting a lamp with
a power source as well.
[0067] In many embodiments, the lamp may further comprise one or
more optical element for distributing light. As used herein, the
term "optical element" may generally refer to a combination of
diffuser(s), any reflector(s), and any associated light management
facility(ies) (e.g, lenses). In many embodiments, an optical
element may comprise a diffuser/and or reflector. Any of the
diffusers described herein, regardless of shape or construction,
may exhibit a white appearance when the lamp is not operating.
[0068] Typically, the one or more optical element is configured to
provide a substantially uniform omnidirectional light distribution
from the lamp when the lamp is in operation. For example, such a
substantially uniform omnidirectional light distribution provides
illumination across a latitude span of from 0.degree. to
135.degree. which is uniform in intensity within about +/-20%.
[0069] The term "omnidirectional" with respect to light
distribution may be described or defined in contemporaneous Energy
Star guidelines, or e.g., refers to a light distribution which
varies in intensity by a value of no more than +/-about 20% from
any point taken from the zenith of a lamp, to a point disposed at
an angle of about 135.degree. from the zenith. Many optical
elements which are described in Provisional Patent Application Ser.
No. 61/643,056 filed on May 4, 2012 (the disclosure of which is
incorporated herein by reference in its entirety), may be employed.
Other possible optical element may be any of those which are
disclosed in the following commonly owned US patent applications,
each of which is hereby incorporated by reference in the entirety:
U.S. patent application Ser. No. 13/189,052, filed 22 Jul. 2011 (GE
Docket 254037); U.S. patent application Ser. No. 13/366,767, filed
6 Feb. 2012 (GE Docket 256707); US patent Publication 2012-0080699,
published 5 Apr. 2012 (GE Docket 245224); 2011-0169394, published
14 Jul. 2011 (GE Docket 241019); US patent Publication
2011-0080740, published 7 Apr. 2011 (GE Docket 240966).
[0070] Referring now to FIGS. 1 and 2, these figures refers to a
first embodiment of an actively cooled lamp 1000 in accordance with
this disclosure. FIG. 1 is a perspective line view of the exterior
of such lamp 1000, hereinbelow described from a top end T to a
bottom end B. Note that the top end T and bottom end B are only
used for convenience' sake, since lamp 1000 may be used in any
orientation. FIG. 2 is an isometric side view of such lamp 1000.
Lamp 1000 is seen to comprise a diffuser 1001 of generally
curvilinear outline (shown here as substantially ovoid in shape and
having an axis of rotational symmetry which is parallel and/or
coincident with an axis of lamp 1000; see line A-A in FIG. 1),
which functions to diffuse and distribute light emitted from one or
more solid state light sources (not specifically shown), such as an
array of LED dies. Typically, LED devices or chips may be mounted
on a circuit board, which is optionally a metal core printed
circuit board (MCPCB). In many embodiments, all of the solid state
light emitting sources may be inorganic light emitting diodes,
although it is possible in certain embodiments to replace some or
all of these with other solid state light emitting sources such as
solid state lasers or organic electroluminescent devices
(OLED).
[0071] A plurality of light emitting diode (LED) devices are
typically selected to provide light which appears white. That, is,
one or more LED chips may be selected having respective spectra and
intensities that are capable of being mixed to generate white light
of a desired color temperature and color rendering ability. For
example, one or more LEDs may emit substantially red light, while
one or more other LEDs may emit substantially green light, while
one or more yet further LEDs may emit substantially blue light.
There are numerous other configurations of LEDs to achieve white
light which would be readily apparent to the person having skill in
the art, such as configurations which employ phosphor coating
either in proximity to at least one LED and/or phosphor coating
remote from at least one LED. For example, a lamp may employ at
least one blue LED having a YAG phosphor, or all of the LEDs in a
lamp may be blue LEDs with YAG phosphor.
[0072] Elsewhere in this disclosure, the combination of a diffuser
and a plurality of solid state light sources may be referred to as
an "optical element", and it is to be understood that what is shown
here as a diffuser 1001 is merely the exterior of an optical
element. As is also described elsewhere in this disclosure, there
may be also numerous other facilities (not shown here) contained
within a diffuser 1001, such as reflectors, waveguides, lenses,
and/or other facilities for manipulating light.
[0073] Diffuser 1001 may be capable of providing substantially
"omnidirectional" light, e.g., as that term may be described in
contemporaneous Energy Star guidelines, or e.g., refers to a light
distribution which varies in intensity by a value of no more than
+/-about 20% from any point taken from the zenith Z of lamp 1000 to
a point disposed at an angle of about 135.degree. from zenith
Z.
[0074] With continuing reference to FIGS. 1 and 2, the diffuser
1001 is generally received within a thermal management system 1005,
which may comprise a heat sink having a main body 1003 and a
plurality of heat radiating surface-area enhancing structures, such
as fins 1002. Although eight fins 1002 are shown here, this should
not be taken as limiting, as a greater or lesser number may be
employed, depending upon numerous factors including one or more of:
the amount of heat needed to be dissipated to the ambient;
optimization of air flow from nozzles (to be described below);
and/or blockage or passage of light from the diffuser 1001. Fins
1002 are generally disposed as protrusions from the body 1003 and
are placed in a circumferential disposition relative to the
diffuser 1001. In many lamp embodiments of this disclosure, fins
are made to be substantially planar and configured to lay in
constant longitude planes. This has the technical effect of
minimizing the impact of the fins on the uniformity of longitudinal
light intensity. In some embodiments of this disclosure, any heat
dissipating surface area enhancing structure (e.g., fin) can be
integral with the heat sink body, or can be attached (e.g., by
adhesive, welding, bolts, screws, rivets, etc.) to it. Multiple
fins may be provided as part of a unitary structure, as individual
structures or as any suitable combination of unitary and combined
structures.
[0075] Generally, thermal management system 1005 may comprise a
material having a high thermal conductivity, such as a metal such
as aluminum and/or copper. The body 1003 of such system 1005 may be
cast from metal, and the fins 1002 may be welded to body 1003 or
similarly cast as one piece or several pieces. In this embodiment,
there may also be "finlets" (i.e., fins of lesser axial length than
fins 1002) provided in an interstitial position between some or all
of fins 1002. Finlets may be sized and positioned in such a manner
that they are in the shadow area, i.e., they typically do not block
light emission from the optical element or diffuser of the
lamp.
[0076] Received within the body 1003 is an active cooling unit or
active cooler or cooling device (not shown here since it is not
visible from this exterior view of lamp 1001), which active cooler
may comprise a synthetic jet assembly. A synthetic jet provides an
oscillating air flow which may efficiently and effectively direct
relatively cooler air from the ambient, towards the proximity of
fins 1002, so as to carry heat away from lamp 1001. To facilitate
the directing of air, a plurality of nozzles 1006 are provided in
body 1003. These nozzles may be holes drilled in, or otherwise
provided as through-holes in the main body 1003. The nozzles 1006
may be provided in a mid-section of the heat sink body 1003, as
measured from the uppermost portion of the body 1003 to a lowermost
portion, relative to zenith Z. As shown on this embodiment, each
fin 1002 may have a pair of nozzles 1006 proximate to a basal edge
1002a of each fin 1002. Their function and effect will be described
hereinbelow.
[0077] In this embodiment, a driver housing 1007, which may be of
generally frustoconical profile, is affixed to the thermal
management system 1005. Housing 1007 encloses electrical and
electronic driver(s), controller(s), and associated wiring (not
shown here since they are obscured by the housing 1007). The
electrical and electronic driver(s) and controller(s) typically are
dedicated to driving and providing the proper electrical signals
for both the one or more solid state light sources (such as array
of LED dies), and for the active cooler. That is, the active cooler
enclosed in body 1003 typically does not have its associated
circuitry (e.g., ASIC) enclosed in body 1003; its associate
circuitry is rather enclosed in housing 1007 and is remote from
body 1003. Finally, at bottom end B of lamp 1001 is base 1008,
which may be a typical Edison-base for screwing to sockets to
receive electrical current, or may be other base for receiving
current, such as pins, prongs, bayonet bases or caps, bi-post,
bi-pins; or the like.
[0078] Turning now to FIG. 3, is depicted a line drawing of a top
view of the lamp 1000 of the first embodiment, showing view of top
of diffuser 1001 from zenith Z, and fins 1002, and a ledge of body
1003.
[0079] FIG. 4 is intended to show a cross-sectional view of lamp
1000, to visualize the interior of diffuser 1001 and to show at
least a portion of the active cooling unit 1011. The plane of cross
section in FIG. 4 is one which is collinear with the major axis of
lamp 1000. Although the diffuser 1001 may have many configurations
as described in detail elsewhere to enable substantially
omnidirectional light output, in this embodiment diffuser 1001
encloses a reflector 1010. More particularly, this view shows an
active cooling unit 1011 (e.g., synthetic jet) substantially
enclosed in a cavity within heat sink body 1003.
[0080] FIG. 5 depicts a partial cross section view of a lamp of the
first embodiment, in which all components are hidden, except for
the thermal management system 1005 comprising a heat sink body 1003
and fins 1002, and active cooling unit 1011. The view of FIG. 6 is
intended to more clearly depict the manner in which the heat sink
body 1003 is itself a "housing" for the active cooling unit 1011;
that is, the active cooling unit (e.g., synthetic jet) 1011
typically does not itself have its own dedicated housing. Although
not described in detail here, effective electrical wiring is
received in active cooling unit 1011 from the driver electronics in
housing 1007 (FIG. 1). Such wiring provides current with an
appropriate signal to drive the actuation of the active cooling
unit 1011. Also, there exists effective electrical wiring received
in active cooling unit 1011 from the driver in driver housing 1007,
which then extends to the solid state light source so as to power
the solid state light source (array of LED chips). Such wires may
extend through the cavity which receives (or contains) the active
cooling unit 1011, and typically are routed around the active
cooling unit 1011 itself. In this embodiment, an array of LED
chips/dies (not shown) is positioned (directly or preferably
indirectly) on a substantially planar upper platform 1012 of heat
sink body 1003. For example, the LED chips may be placed on a MCPCB
(metal core printed circuit board), which may be affixed using a
thermal paste. The array of LEDs are thus in thermal communication
with the thermal management system and heat sink body 1003. FIG. 6
is similar to the view of 5 except that the view of the active
cooling unit 1011 is also hidden, so as to reveal the cavity 1013
within the heat sink body 1003 within which the active cooling unit
1011 is substantially enclosed. Also revealed in FIG. 6 is a
divider plate 1014 which separates (and, e.g., electrically
insulates) the active cooling unit 1011 from the housing 1007.
[0081] Turning now to FIGS. 7 and 8, these are partial depictions
of lamp 1000 in a simplified cross-section, showing numerous fins
removed and a simplified version of the active cooling unit 1011.
These latter two Figures are intended to depict some salient
features of the active cooling of the lamp when in a typical normal
mode of operation. Since synthetic jets function in an oscillatory
manner, drawing air in during one cycle, and then expelling air out
during another cycle, any given nozzle 1006 may at one time be an
intake nozzle for drawing air in, and at another time be an exhaust
for jetting air out. FIG. 7 shows one portion of a cycle, where air
1020i is taken in from the ambient ("i" for in) to a nozzle 1006 on
a right hand side of lamp 1000; and, then from another nozzle 1006
in a different location, cooling air is jetted or expelled so as to
flow generally upwards in stream 1020o (letter "o" for out). The
smaller arrows generally parallel to the arrow for 1020o
schematically depicts air from the ambient which is entrained along
with the flow of expelled air 1020o. Therefore, based on the
position of the nozzles 1006 at the basal edge 1002a (FIG. 1) of
fin 1002, cooling air 1020o is made to flow along essentially an
entire axial length of fin 1002, so as to provide effective heat
dissipation. FIG. 8 shows another portion of the cycle, in which
the nozzle 1006 which had expelled air, is now the intake for air
1020i, and the nozzle which previously drew air in, now expels air
in a flow 1020o along the length of another fin (not shown, removed
for clarity).
[0082] Referring now to a second embodiment of an actively cooled
lamp, FIG. 9 depicts a perspective external view of an actively
cooled lamp 1100, characterized at least in part by a diffuser 1101
having, in this embodiment, a substantially toroidal shape with an
axis parallel to a major axis of lamp 1100. This view in FIG. 9
permits arrays of individual solid state light emitting elements
(e.g. LED chips) 1112 to be seen for explanation's sake, although
in practice the diffuser will be substantially translucent such
that individual LED chips 1112 will typically not be perceptible
either when the lamp is either energized or not energized. In this
embodiment, diffuser 1101 at least partially encircles a heat sink
body 1105, which is provided as a cast metallic barrel
substantially coaxial to the major axis of lamp 1100. That is, the
heat sink body 1105 is in a central position relative to a
peripheral diffuser 1101. Heat sink body 1105 is shown here as
having a "snowflake" cross-section, but it is to be understood that
the heat sink body may be any shape provided that it comprises
channels 1110a for cooling air to flow from an active cooler (1111,
FIG. 12) proximate a lower axial portion of heat sink body 1105, to
an upper axial portion of body 1105.
[0083] FIG. 10 shows a portion of lamp with the diffuser and solid
state light sources hidden. For example FIG. 10 shows body 1105 as
having bored or cast through holes 1114 which permit cooling air to
flow from an active cooler proximate a lower axial portion of heat
sink body 1105, to an upper axial portion of body 1105.
[0084] Returning to FIG. 9, the channels 1110a are defined by the
slats or fins 1110 which may extend radially (relative to a circle
defined by toroidal diffuser 1101) from body 1105. These slats or
fins 1110 are surface-area enhancing heat dissipating elements. The
channels permit air ejected from nozzles 1106 to flow over
substantially the entire axial length of heat sink body 1105. The
lamp 1100 comprises a plurality of nozzles 1106 directed
substantially axially upward (relative to a base 1108 being a
"bottom" and a heat sink 1105 being a "top" of a lamp) to permit
air to be passed through a plurality of channels 1110a and
proximate the length of slats or fins 1110. Nozzles 1106 also
permit air to be alternately taken in by an active cooler (e.g.,
synthetic jet, not specifically shown) and then propelled from the
active cooler, depending upon which cycle of the "breathing" mode
of operation the active cooler is operating.
[0085] In a similar manner to the first embodiment described above,
lamp 1100 also comprises a driver housing 1107 which may enclose
driver/controller electronics for both the active cooler and for
the solid state light sources (e.g., LED chips 1112).
[0086] The array of LED chips 1112 depicted in FIG. 9 are disposed
on a lateral surface of the substantially barrel-shaped heat sink
body 1105. In this embodiment, heat sink body 1105 has a polygonal
cross section, and the LED chips 1112 are mounted, generally
indirectly, on a planar side of this heat sink body having a
polygonal cross section. For example, the LED chips may be placed
on a MCPCB (metal core printed circuit board), which may be affixed
using a thermal paste. Mounting may be accomplished in any
effective manner provided that efficient thermal communication is
established between the LED chips 1112 and the heat sink body 1105.
For example, one convenient manner in which to dispose LED chips is
to provide a plurality of LED chips premounted on a board 1113.
Although not specifically shown here, one embodiment comprises
providing a thin flexible board 1113 onto which LED chips are
premounted, which may have a thickness of 0.01 inches or less,
which is then wrapped around a circumferential periphery of the
heat sink, akin to a rim on a wheel. Such flexible board may be
adhered to the heat sink 1105 by an ultra-thin epoxy adhesive. The
plurality of LED chips 1112 emit light radially in this embodiment
towards the interior of the diffuser 1101, which latter element
functions to re-direct light so as to provide a substantially
uniform, preferably "omnidirectional" (as defined above) light
radiating pattern from lamp 1100. For provision of electrical
current, a base 1108 is provided, which may be a standard
Edison-type screw base or any other effective manner of connecting
lamp 1100 to an external source of current, such as pins or
pegs.
[0087] Turning now to FIG. 11, a bottom perspective view of a
portion of an actively cooled lamp in accordance with this second
embodiment is shown, but with several elements hidden: diffuser,
LED chips and board, and cover for active cooler. This view is
intended to show the positioning of an active cooler (active
cooling unit, synthetic jet) 1111 beneath/below a barrel-shaped
heat sink body 1105 having longitudinal channels or through-holes
1114. While this view does not accurately represent the actual air
flow from the active cooler 1111 into the channels 1114, it is
intended to be illustrative of the source of the air flow (cooler
1111) and its position of ingress into the body of the heat sink
(viz., channel 1114).
[0088] FIG. 12 is a top perspective sectional view of a lamp 1100
according to this second embodiment. In this figure, the heat sink
body 1105 is chosen as having the snowflake-shaped cross section,
of which 1110 is one representative slat/fin, although of course
the body can be any shape, preferably substantially cylindrically
symmetrical. In this figure, a synthetic jet 1111 is visible. A
plurality of nozzles 1106 permit cooling air to be alternately
pulled in to the synthetic jet and ejected from the synthetic jet,
depending on the stage in the cycle of operation of the synthetic
jet. Here, an air flow into one nozzle 1106 is shown as air flow
1116 on the left side of this schematic depiction; owing to the
operation of the synthetic jet, a directed air flow 1117 is
directed generally upwardly from another nozzle, and then into a
space between the slats 1110 of this heat sink body 1105, so as to
remove heat to the ambient.
[0089] FIGS. 13-15 depict various views of a third embodiment of an
actively cooled lamp 1200 in accordance with certain aspects of
this disclosure. In this embodiment, actively cooled lamp 1200 is
characterized, in part, by an active cooler 1211 which is in a
spaced-apart relationship with a heat sink 1205, to permit a
greater possibility of entrainment of air into/with air that is
emitted from active cooler 1211. In particular, FIG. 13 is a top
perspective line-drawing view of a lamp 1200 having a heat sink
body 1205 possessing a barrel-shape with a substantially polygonal
or annular cross section, which has an axis parallel/coincident
with a major axis of lamp 1200. It is substantially encircled at
its periphery by a substantially toroidal diffuser 1201, which
re-directs light emitted from solid state light emitting elements
such as LED dies 1212; these dies 1212 emit light within the
diffuser in a substantially radially direction, which is then
mixed/diffused/re-directed to give an appropriate external light
emission, e.g., an omnidirectional light emission pattern. The LEDs
1212 may be placed on a flexible board which wraps a
circumferential periphery of the heat sink body 1205. In this
regard, this third embodiment shares similarities to the second
embodiment. However, heat sink body 1205 here does not possess
through holes or channels which penetrate from a bottom of a heat
sink body to a top of a heat sink. Rather, in this embodiment, the
heat sink may comprise slats or fins 1210 extending or protruding
in a substantially downward axial direction. Slats/fins 1210 may
also be replaced in part or in whole by a pin or pin forest or
other heat-dissipating, surface area enhancing shapes.
[0090] Slats or fins 1210 are better seen in cross-sectional side
view FIG. 14, in which pairs of the plurality of slats 1210 define
radial channels 1214. This view also depicts the positioning of
heat sink body 1205 on a stanchion, post, or pin 1204 so as to
attain its spaced-apart relationship from active cooler 1211.
Although in this view, the active cooler 1211 is shown to be a
vertically positioned synthetic jet, it may also be a synthetic jet
positioned in any effective orientation, or any other active cooler
such as a fan or piezojet.
[0091] Although active cooler 1211 is generally substantially
contained within an enclosure, air ejected therefrom is directed
towards slats 1210 and heat sink body 1205 by passage through slots
1206. FIG. 15 is a bottom perspective cutaway operational view,
depicting passage of air 1217. Active cooler 1211, if operated in
an oscillating mode (as would a synthetic jet), is seen to take
inflowing air 1216 through one slot 1206. Substantially
simultaneously, ejected air 1217 flows outward from another slot
and impinges the slats/fins 1210, and may flow into the channels
(1214; FIG. 14) defined by slats/fins 1210. The slots are shown
here as extending along a line which is substantially normal to the
channels 1214, so as to enhance "air-turning" of the ejected air,
as well as entrainment of ambient air which has not been ejected
from active cooler 1211. However, slots above the active cooler and
the channels defined by slats can be at any effective angle
relative to each other, e.g., parallel.
[0092] Returning to FIG. 13: driver housing 1207 may enclose
electronic circuitry (not shown) for driving/controlling both the
active cooler and the plurality of LED dies 1212. Current may be
provided to the LED dies 1212 by extending wiring (not shown)
through troughs or holes in post 1204 and body 1205. Base 1208 may
be an Edison base or any other base capable of providing mains
current to lamp 1200.
[0093] In this fourth embodiment, shown in side view in FIG. 16 and
cross section in FIG. 17, a lamp 1300 comprises heat dissipating
surface area enhancing structures of at least two types. These heat
dissipating surface area enhancing structures include, in this
embodiment, a plurality of fins 1302 of relatively longer axial
length and a plurality of finlets 1304 of relatively shorter axial
length, wherein the number of finlets is greater than the number of
fins. In this embodiment, an active cooler 1311 (e.g., synthetic
jet) propels cooling air out through nozzles (not shown) which
comprise positions at a location proximate the axial bottom of
finlets 1304. Generally, such nozzles may be formed as holes in the
driver housing 1307, rather than as apertures in heat sink 1303;
however, it is also possible for nozzles to be formed in any
combination of apertures in the heat sink 1303 and apertures in the
driver housing 1307. Generally, this embodiment exemplified a lamp
wherein nozzles may eject a cooling air stream to flow along
essentially the entire length of at least one heat dissipating
surface area enhancing structure (e.g. a finlet 1304). In
operation, the ejected cooling air stream may entrain ambient air
to increase the mass flow of air which functions to cool the
lamp.
[0094] The optical element 1301 (e.g., optical management system,
which may comprise at least a diffuser and a reflector 1310)
functions, in operation, to distribute light emitted from a
plurality of solid state light sources (e.g., LED chips, not
shown). The plurality of solid state light sources are positioned
on an upper, outer surface of heat sink 1303, and in thermal
communication therewith. The plurality of solid state light sources
emit light in an generally axially upward fashion in this
embodiment. Generally, this embodiment exemplifies a lamp having a
majority of its heat dissipating surface area enhancing structures
(e.g., fins) positioned in the shadow of the light distributed by
the optical element. That is, in this embodiment, all of the
finlets 1304 are sized and positioned such that they do not block
light emitted from the optical element 1301, while the optical
element 1301 distributes light in an omnidirectional fashion (e.g.,
a light distribution which varies in intensity by a value of no
more than +/-20% from any point taken from the zenith of a lamp to
a point disposed at an angle of 135.degree. from the zenith).
[0095] In a fifth embodiment of a lamp in accordance with this
disclosure, lamp 1400 is depicted in a side view in FIG. 18. In
this schematic embodiment, a lamp 1400 is sized and shaped to
conform essentially to the form factor of an A19 profile is
provided, but it is to be understood that features of this
embodiment, as well as the features of the other embodiments
described in this disclosure, may independently be adapted for use
in a wide variety of lamp profiles. Optical element 1401 is
intended to embrace a plurality of components to manage light
emitted by a plurality of solid state light emitting sources (e.g.,
LED chips, not shown in this view). Such optical element may
comprise any configuration effective to disperse light emitted from
LED chips, including many known configurations. In one embodiment,
the optical element is adapted to provide a substantially
"omnidirectional" distribution of light, as that term is elsewhere
defined and described. Element 1401 generally comprises a dome
shaped diffuser 1401a. Although generally not visible to the eye
when viewed from an exterior vantage point (since diffuser 1401a
may be translucent or opaque), a reflector 1410 is shown in this
schematic view. Reflector 1410 may act to redirect light initially
emitted in an upward axial direction, towards an obtuse angle
relative to the top of the lamp. The "top" of the lamp is shown as
T in this FIG. 18 for convenience, but it is to be understood that
the lamp may be operated or viewed from any position.
[0096] The solid state light emitting sources (e.g., LED chips or
LED array, not shown here) of lamp 1400 are the main source of heat
which must be dissipated to the ambient, and so therefore such
solid state light emitting sources are mounted (generally in a
substantially planar configuration) in thermal communication with
heat sink 1403, preferably at an substantial zenith of the heat
sink 1403 and disposed below an axis of reflector 1410. Extending
from heat sink 1403 are a plurality of fins 1402 (e.g., thermal
fins or heat dissipating surface area enhancing structures), which
comprise a thin arcuate shape. The fins 1402 may be described as
spaced apart from each other along a circumferential direction of
the heat sink 1403. As also described elsewhere, fins are
configured to facilitate the conduction of heat from the heat sink
to the ambient. Although a given number of fins may be deduced from
this and other figures of this embodiment, it is to be noted that
the number of fins is not strictly limited.
[0097] Also protruding from heat sink 1403 are a plurality of
(optional) finlets 1404, which may be defined as heat dissipating
surface area enhancing structures akin to a fin, but with a lesser
axial length dimension than fins 1402. That is, one may describe
the pattern shown in 18 as having a plurality of relatively long
fins and a plurality of relatively short fins (i.e., these being
the finlets). In this embodiment, the finlets 1404 are seen to
alternate circumferentially with the fins 1402, although they may
coexist in any pattern or be absent. The axial dimension of fins
1402 is usually sufficient to extent from a base of heat sink 1403
to a region proximate a diffuser 1401a.
[0098] Although not visible in the view of FIG. 18, an active
cooling device (e.g., synthetic jet) is received within a cavity
defined by an interior of heat sink 1405. The active cooler may be
any known active cooler, such as a fan, but is more usually a
synthetic jet. The active cooler of lamp 1400 (in operation)
creates an air flow which (after appropriate diversion) is
propelled to flow (at least in part) in an axial direction from a
bottom lip of the heat sink 1403 along substantially the full
length of at least one fin 1402 (as will be described in greater
detail below in reference to FIGS. 21-23). Preferably, air flow is
propelled to flow (at least in part) in an axial direction from a
bottom lip of the heat sink 1403 along substantially the full axial
length of the heat sink.
[0099] A housing (e.g., driver housing) 1407, which may be made at
least in part of a plastic or polymeric material, is positioned
below the heat sink and exists to enclose and protect driver and
electronic controller circuitry (not shown) used to drive and
control the solid state light source (e.g., LED chips) and the
active cooler. The housing 1407 is generally of an inverted
frustoconical shape, with its annular base proximate to the heat
sink.
[0100] Importantly, in this embodiment, nozzles or apertures from
which air may be ejected, are generally not wholly formed as holes
in either heat sink 1403 or housing 1407. Rather, the nozzles may
be formed as a gap created after housing 1407 and heat sink 1403
are mated, joined, or affixed. The gaps are better seen from the
top view of FIG. 20 as element 1405a. To facilitate the formation
of gaps, the housing 1407 may comprise at least one notch 1406 in a
region of the housing 1407 which is proximate to bottom of heat
sink 1403, each of which notch 1406 is axially beneath a finlet
1404. The notches 1406 in the housing 1407 alternate with regular
portions 1405 of the housing 1407; that is, the notches 1406 are an
irregular inward deviation from the regularity of the inverted
frustoconical profile of housing 1407, while the regular portions
are merely the residual portion 1405 of the housing which maintains
this profile. In this embodiment, each regular portion 1405 is
axially beneath a fin 1402. Although not visible in this view,
cooling air may flow axially along an interior surface of a regular
portion 1405. Lamp 1401 is provided with mains current by a base
1408, shown here as an Edison base, although it is not limited to
this type of base.
[0101] FIG. 19 is a side view of a lamp 1400 with housing 1407
removed from view, so as to reveal a lower portion of an active
cooler 1411. Although a majority of the active cooler 1411 along an
axial length dimension may be enclosed by heat sink 1403, a small
portion of active cooler may extend into an interior of housing
1407. Also revealed in this view are female apertures 1412 along a
bottom rim or lip of heat sink 1403, which act to receive suitable
male projections from an interior surface of housing 1407. That is,
housing 1407 and heat sink 1403 generally mate (e.g., snap fit,
e.g., a one way snap fit) in this embodiment, and apertures 1412
facilitate this. Of course, this disclosure is not limited to this
particular manner of affixing housing 1407 to heat sink 1403, as
one may contemplate other manners of affixing, including those
which employ grooves, notches, friction fit, threading, screws,
bolts, adhesives, or any appropriate connecting means. Finally,
1413 is a schematic depiction of a driver/controller chamber.
[0102] FIG. 20 is a top view of lamp 1400, but with the optical
element 1401 (i.e., including 1401a, 1410) removed. This reveals a
mounting area 1414, upon which may be mounted a plurality of solid
state light emitters (e.g. LED chips; not specifically shown),
generally disposed to radiate light axially upward towards top T
(FIG. 18). Mounting area 1414, which itself may be a planar shelf
at a zenith of the heat sink 1403, is in thermal communication with
heat sink 1403, so that heat sink 1403 acts as the primary intended
conduit for conducting heat away from the plurality of solid state
light emitters. Also visible in the top view 20 is the plurality of
fins 1402 and finlets 1404, seen in axial cross section. Each fin
1402 bisects or traverses a gap 1405a which is defined by the
interior surface of regular portion 1405 of the housing 1407. In
operation of the lamp, cooling air (not shown) is ejected through
gap 1405a (or alternately is taken into a gap 1405a and is ejected
through that same gap 1405a, if the active cooler is a synthetic
jet).
[0103] FIG. 21 is a perspective close-up view of lamp 1400 at the
juncture of the heat sink 1403 and housing 1407, showing in better
detail how gaps 1405a are formed by cooperation between the bottom
edge of heat sink 1403 and regular portion of housing 1407. Note
that air flow is shown as axial arrows emanating in a generally
upward direction, to flow (at least in part) in a pathway adjacent
a side of a fin 1402. Ultimately, air is made to flow along
essentially the entire axial length of fin 1402. In this
embodiment, air flows generally upwards on both sides of fin 1402
from each gap 1405a. That is, when a gap 1405a is acting as a
nozzle for ejected air, it may be positioned to allow air to flow
in an axially upwards pathway adjacent both lateral sides of a fin
1402.
[0104] FIG. 22 depicts a view of the interior contour of housing
1407 at a location adjacent to the annular "base" of the inverted
frustoconical shaped housing. It is an expanded view of an interior
surface of regular portion 1405 (seen from the exterior in FIGS. 18
and 21), as well as part of an interior surface of notch 1406.
Importantly, the gap 1405a is divided at its interior into two
regions by a diverter 1415, which may comprise a blade edge 1416.
The bladed diverter 1415 acts (in operation) to divert air flow
propelled from an active cooler into two separate streams, as air
flow impinges blade edge 1416; the division of air flow is
schematically depicted in FIG. 22 by a single upward arrow and two
angled arrows. One possible technical effect enabled by the
provision of a bladed air flow diverter is to significantly reduce
acoustic noise as air passes through and out from gap 1405a. In
fact, such or similar bladed air flow diverter may be employed
within a nozzle in any embodiments of the disclosure for the same
purpose. A bladed air flow diverter may comprise plastic and/or
metal.
[0105] FIG. 23 is a schematized view of an assembled lamp 1400 in
operation, showing a region where cooling air flow is ejected from
active cooler 1411 to escape through gap 1405a. Where active cooler
1411 comprises a synthetic jet, movement of diaphragms may cause
air to flow around an end of a rounded lobe of heat sink 1403,
impinge diverter 1415, and flow out gap 1405a. Only one size of
divided gap 1405a is shown here. The rounded end of lobe of heat
sink 1403 also may contribute to acoustic noise reduction when air
flows around such end. Importantly, in this embodiment, at least
some of the air flow emanating from synthetic jet 1411 must be
turned in direction. Therefore, the heat sink and housing may
typically be configured such that whenever air is turned (e.g., in
any angle>90.degree.), it should be made to flow around at least
some rounded edges; for example, whenever air must turn in
direction around an angle of >90.degree., substantially no edges
which are traversed or passed are sharp edges. Although not limited
by the following theory, it is believed that the rounded end of
lobe of heat sink 1403 and other rounded edges, contribute to
reduced acoustic noise reduction by avoiding the formation of
vortices. In embodiments of the disclosure, air is generally guided
gently around turns; in contrast, if air is guided around sharp
edges, a vortex may be created which can contribute to acoustic
noise.
[0106] The exploded view shown in FIG. 24 permits one to describe
one embodiment in which lamp 1400 may be assembled. While a
specific ordering is described herein, it should be understood that
any effective order of assembly may be employed in this and other
embodiments of actively cooled lamps of this disclosure. Generally,
a mounted assembly 1422 of LED chips, e.g., on a printed circuit
board is placed into thermal communication with a substantially
planar shelf 1414 of heat sink 1403, and the assembly 1422 is
thereafter framed by mount 1423, which holds down or otherwise
fastens assembly 1422 to shelf 1414. The mount may generally
comprise a thermoplastic material, and may alternatively be
attached to a heat sink or shelf by a thermal process which
partially melts a part of the mount. Alternatively, the mount may
comprise protrusions which pass through holes in the heat sink, and
the portion which passes through the holes is at least partially
melted to secure the mount and the assembly of LED chips to the
heat sink, without the use of screws.
[0107] In certain embodiments, any plastic material which is used
to form the substantially planar shelf 1414, the mounted assembly
1422 of LED chips, and/or the mount 1423, is selected to be
partially or fully specular.
[0108] The optical element 1401 may comprise a hemispherical
diffuser cap (e.g., diffuser dome 1401a), which had been visible in
other views in several figures described above; a reflector 1410,
and a complementary hemispherical diffuser part 1401c having a
bottom aperture sized and configured to encircle mount 1423. Thus,
complementary hemispherical diffuser part 1401c is placed over
mount 1423 so that the mounted assembly 1422 of LED chips may emit
light axially upwards in operation through the bottom aperture of
complementary hemispherical diffuser part 1401c; then the
circumferential rim of reflector 1410 is seated on an upper rim of
complementary hemispherical diffuser part 1401c, and diffuser dome
1401a is affixed to the reflector 1410 and part 1401c. The LED
chips may be within the envelope of the diffuser, or may be spaced
apart from the envelope of the diffuser.
[0109] After assembling synthetic jet 1411 (not described in detail
here), the substantially complete synthetic jet 1411 is placed into
a substantially cylindrical interior cavity (not shown) of heat
sink 1403. In lamp 1400, there typically exists a divider plate
1420 to separate the synthetic jet 1411 from the electronic
driver/controllers (not shown) to be enclosed by housing 1407. This
divider plate 1420 is placed on a bottom end of synthetic jet 1411
after its placement into heat sink 1403. Such a divider may avoid
the possibility of blowing air unnecessarily into the interior of
the housing, and may contribute to preventing electrical shorts.
Although not specifically shown, housing 1407 will enclose
electronic driver/controllers; housing 1407 will be snap-fit or
otherwise securely fastened to heat sink 1403. Item 1421 is the
threading required to fasten lamp 1400 into an Edison socket.
[0110] In a sixth embodiment of an actively cooled lamp, FIGS. 25
and 26 depict schematic side views of a lamp 1500 comprising a
diffuser 1501, heat sink 1503 comprising heat dissipating surface
area enhancing structures 1502, a compartment 1506 for an active
cooler (such as synthetic jet 1511), and driver housing 1507. In
FIG. 26, diffuser 1501 is made to be transparent for purposes of
the view. The heat sink 1503 comprises an upper portion 1504 with
generally bolt shape and a lower portion comprising parallel slats
1502 projecting downwardly. The heat sink 1503 used in the
embodiment of lamp 1500 is more clearly shown in front view and
perspective view FIGS. 27-28, respectively. An outer lateral
surface of upper portion 1504 supports a plurality of solid state
light emitting sources (e.g., LED chips, not shown). Diffuser 1501
comprises a generally toroidal shape, with its concave inner
surface being essentially hollow. Light from the plurality of solid
state light emitting sources emit light radially (e.g.,
substantially normal to major axis of lamp 1500) to impinge upon an
inner circumferential surface of diffuser 1501, and thereby be
redirected. The compartment 1506 is a generally truncated cylinder,
with a closure at the top for seating the heat sink 1503, and an
open bottom and cavity for receiving an active cooler 1511. In FIG.
26, compartment 1506 is made to appear transparent, to expose
active cooler 1511. Driver housing 1507 comprises driver
electronics and controllers for both the active cooler 1511 and the
plurality of solid state light emitting sources.
[0111] Any of the actively cooled lamps described or suggested by
embodiments of the present disclosure, may be designed as direct
"plug in" components that mate with a lamp socket via: a threaded
Edison base connector (sometimes referred to as an "Edison base" in
the context of an incandescent light bulb); a bayonet type base
connector (i.e., bayonet base in the case of an incandescent light
bulb), or other standard base connector to receive standard
electrical power (e.g., 110 volts A.C., 60 Hz in the United States;
or 220V A.C., 50 Hz in Europe; or 12 or 24 or other d.c. voltage).
Since many actively cooled lamps of this disclosure do not rely
predominantly upon conduction of heat into the lamp socket via the
base, actively cooled lamps of this disclosure may be used in any
standard threaded light socket without concern about thermal
loading of the socket or adjacent hardware.
[0112] Actively cooled lamps in accordance with embodiments of this
disclosure may be particularly well suited for retrofitting higher
wattage incandescent bulbs, such as incandescent bulbs in the 60 W
to 100 W or higher range. In some aspects of the present
disclosure, there are provided actively cooled lamps that may
provide lumen output of at least 600 lumens, and in some
embodiments at least 800 lumens, at least 950 lumens, at least 1300
lumens, at least 1500 lumens, at least 1700 lumens, at least 1800
lumens, or in some cases even higher lumen output. For example,
certain actively cooled lamps in accordance with the present
disclosure may output substantially the same lumens as a standard
100 watt tungsten filament incandescent lamp, but at a fraction of
the power input (e.g., when driven at approximately 27 W).
[0113] In general, actively-cooled lamp embodiments of embodiments
of the present invention are capable of simultaneously achieving
all of the following parameters when in operation: (1) a lumen
output of 1600 lumens or greater (e.g., greater than 1700 lumens);
(2) a distribution of emitted light which is omnidirectional (e.g.,
illumination is provided across a latitude span of from 0.degree.
to 135.degree. which is uniform in intensity within about +/-20%);
(3) a geometric configuration which fits within the A19 envelope
(or which conforms to the ANSI A19 volumetric profile); and (4)
possesses sufficient cooling ability for an efficiency of at least
60 LPW (e.g., >65 lumens per Watt) and/or an L70 lifetime of at
least about 25000 hours. Optionally, actively cooled lamps of
embodiments of the present invention may also further
simultaneously exhibit a correlated color temperature for light
emitted from the optical element of from 2700 K to 3000 K.
Optionally, actively cooled lamps of embodiments of the present
invention may also further simultaneously exhibit a color rendering
index for light emitted from the optical element of greater than
about 80.
[0114] Any appearance of the phrase "solid state emitter" may be
taken to mean the same thing as "solid state light emitting
source", and vice versa. Any appearance of "synthetic jet", without
more, may be taken to mean the same thing as "synthetic jet
actuator", and vice versa. Any appearance of "active cooling
device" may be taken to mean the same thing as "active cooler", and
vice versa. Furthermore, it is to be understood that "air" may be
replaced by any fluid which is suitable for heat dissipation.
[0115] As used herein, approximating language may be applied to
modify any quantitative representation that may vary without
resulting in a change in the basic function to which it is related.
Accordingly, a value modified by a term or terms, such as "about"
and "substantially," may not be limited to the precise value
specified, in some cases. The modifier "about" used in connection
with a quantity is inclusive of the stated value and has the
meaning dictated by the context (for example, includes the degree
of error associated with the measurement of the particular
quantity). "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, or that the
subsequently identified material may or may not be present, and
that the description includes instances where the event or
circumstance occurs or where the material is present, and instances
where the event or circumstance does not occur or the material is
not present. The singular forms "a", "an" and "the" include plural
referents unless the context clearly dictates otherwise. All ranges
disclosed herein are inclusive of the recited endpoint and
independently combinable. In the foregoing description, when a
preferred range, such as 5 to 25 (or 5-25), is given, this means
preferably at least 5 and, separately and independently, preferably
not more than 25.
[0116] While the invention has been described in detail in
connection with only a limited number of embodiments, it should be
readily understood that the invention is not limited to such
disclosed embodiments. Rather, the invention can be modified to
incorporate any number of variations, alterations, substitutions or
equivalent arrangements not heretofore described, but which are
commensurate with the spirit and scope of the invention.
Additionally, while various embodiments of the invention have been
described, it is to be understood that aspects of the invention may
include only some of the described embodiments. Accordingly, the
invention is not to be seen as limited by the foregoing
description, but is only limited by the scope of the appended
claims.
* * * * *