Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02687529 2009-12-03
LED LIGHT BULB
FIELD OF THE INVENTION
The present invention relates to a lighting apparatus and more particularly,
to a
light emitting diode (LED) light bulb having a centralized light source to
provide up and
down lights with an effective forward cooling. The LED light bulb of the
present
invention may be used as a replacement of existing bulbs for both indoor and
outdoor
applications, such as retrofits for incandescent and fluorescent light bulbs.
BACKGROUND OF THE INVENTION
As the public awareness and commitment to carbon reduction worldwide
strengthen, solid state lighting or Light emitting diode (LED) lighting
becomes one of
the solutions to a greener world. Nevertheless, the problems in optical
designs and
thermal management associated with LED bulbs are common and yet to be
improved. It
is known that a significant percentage of the power supplied to LEDs is not
being
converted into light but waste heat that must be handled in order to prevent
damages to
the LEDs, especially for high power LEDs. Additionally, as LEDs are currently
being
packaged into modules having a single light emitting side of a relatively
small area,
designs of light bulbs utilizing LED module(s) must too consider the beam
angles of the
LED modules for a desired illumination.
With regard to the thermal management of LED light bulbs, especially for high
power LED light bulbs, the design utilizing a "back" side or backward cooling
with a
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back-end heat sink is one solution (the analogy of "back" or backward and
"front" or
forward may also be interpreted with respect to the light emitting side of
LED). For
example, U.S. Pat. No. 6,864,513 to Lin, U.S. Pat. No. 7,524,089 to Park, U.S.
Pat. No.
7,581,856 to Kang, EP. No. 2 065 633 to Konaka and JP. No. 2009-37995 to
Morikawa
disclose LED lamps having a heat sink attached to the back side of LED
module(s) to
dissipate the heat via the back heat sink to the ambient. One common problem
associated with backward cooling, either passive or forced-air cooling, of
existing LED
bulbs is the insufficient room and/or air flow available to the heat sink as
the back of the
bulb is installed onto the socket of a lighting fixture. Therefore, such LED
light bulb
may not be optimal for existing lighting fixtures without modifications.
The limits to the angle of illumination of an LED light bulb having a back-
side
heat sink may be better understood with the illustration of a particular
instance chosen
only as an emphasis example. FIG. 1 shows a situation where a common lighting
fixture
of a ceiling-type chandelier having multiple LED bulbs B installed on the
stands facing
toward the ceiling. It can be perceived that as the LED bulbs B are installed
facing
toward the ceiling rather than downward to the floor of the room, due to the
back-side
heat sink occupying the lower portion of the bulb B, the illumination is
significantly
limited and the area directly below the light bulbs may in fact receive no
direct lights.
Different approaches and designs intended to achieve greater angle of
illumination
can be found in other known LED light apparatus; however, the abovementioned
thermal problem associated with LEDs still commonly exists. A known solution
for
wider illumination is to spread the distribution of a plurality of LEDs or
modules within
a lamp such that the outcome of the illumination covers larger angles. U.S.
5,688,042 to
Madadi, U.S. Pat. No. 6,425,678 to Verdes, U.S. Pat. No. 6,709,132 to
Ishibashi; U.S.
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Pat. No. 7,086,756 to Maxik and U.S. Pat. No. 7,086,767 to Sidwell disclose
LED
lamps having LEDs spatially arranged in multiple axes in the lamp to shine
lights in
different directions to achieve greater angle of illumination. Nevertheless,
in terms of
thermal management, the design of cooling to the back of the LED substrates
and heat
sinks may not be sufficient, especially for high power LEDs that require
better heat
dissipation. These light bulbs with spread out light sources may be further
treated as
"frosted" lamps since human eyes in general (being long adapted to lights from
tradition
bulbs in many aspects) may need to be adjusted to adapt to a light source
having point
lights spaced apart to such extend that may not be perceived as a uniform
light source.
Therefore, it may be significant that the angle of illumination of an LED
light bulb is to
be considered along with thermal management.
In view of the forgoing, the challenge is to provide an LED light bulb that
can
effectively dissipate the waste heat generated by the LED light source in the
light bulb
while providing a greater illumination angle relatively similar to that of a
traditional
lamp including at least up and down lights. In addition, it is preferable to
provide an
effective and efficient cooling mechanism utilizing available spaces within
the light
bulb and preferably with passive cooling involving less moving parts to
prevent or
reduce the likelihood of component failures.
SUMMARY OF THE INVENTION
The present invention provides a novel lighting apparatus. According to one
aspect
of the present invention, an LED light bulb capable of effectively dissipating
waste heat
generated by an LED light source with forward cooling utilizing the space
and/or
structure directly in front of the light emitting side(s) of the light source
is provided.
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Another aspect of the present invention is to provide an LED light bulb having
an
LED light source such that the angle of illumination of the LED light bulb is
increased
and the light distribution is uniform to include at least up and down lights
and
preferably without excess use of reflective means or modification to existing
fixtures.
A further aspect of the present invention is to provide an LED light bulb
having an
upper lighting unit and a lower lighting unit capable of providing both up and
down
lights from a light source with an effective forward cooling utilizing the
front space and
structures arranged and configured at a front portion of the light bulb to
dissipate heat to
the front of the light source and via the entire surface of the bulb as a
whole rather than
to the back or the base socket of the light bulb.
According to one embodiment of the present invention, an LED light bulb
capable
of providing at least up and down lights with a forward cooling comprises a
light
transmissive shell, a stem assembly having conductive structures extending
away from a
support block toward both the upper and lower portions of the shell
respectively and an
LED light source arranged and mounted on opposite sides of the support block
to
provide at least up and down lights toward the upper and lower portions of the
shell
along the conductive structures extending directly to a front of light
emitting sides of
the LED light source. The heat originated from the LED light source may then
be
dissipated away from the support block via the conductive structures toward
both the
upper and lower portions of the shell by a way of forward cooling that
utilizes the
structures and the inner space in the front portion of the light bulb as well
as directly
toward the front of the light emitting sides of the light source.
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According to another embodiment of the present invention, an LED light bulb
having a centralized light source with forward cooling comprises a light
transmissive
shell; a stem assembly having first and second conductive structures extending
away
from a support block and toward upper and lower portions of the shell
respectively; an
LED light source comprising LED rings arranged and mounted on opposite sides
of the
support block to provide a uniform lighting including up and down lights;
wherein the
LED rings include light emitting sides toward the upper and lower portions of
the shell
and along the first and second conductive structures extending directly to a
front thereof
and joined to the upper and lower portions of the shell respectively such that
heat
originated from the LED light source is conducted away from the support block
via the
first and second conducive structures to the shell and subsequently the entire
surface of
the shell in the front portion of the light bulb as a whole.
According to still another embodiment of the present invention, an LED light
bulb
capable of providing at least up and down lights with a forward cooling
comprises an
upper lighting part and a lower lighting part attached to a thermally
conducive support
block disposed therebetween and arranged at a front portion of the light bulb.
The upper
lighting part comprises a light transmissive upper envelope, a first
conductive structure
extending away from the support block toward a top portion of the upper
envelope and a
first LED light source comprising a plurality of LEDs facing toward the upper
envelope
to provide up lights. The lower lighting part comprises another light
transmissive lower
envelope, a second conducive structure extending away from the support block
toward a
bottom portion of the lower envelope and a second LED light source comprising
a
plurality of LEDs facing toward the lower envelope to provide down lights. As
the first
and second conductive structures of the stem assembly extend directly to a
front of the
first and second LED light sources, heat originated from the LED light sources
may be
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conducted away to the front thereof toward both the upper and lower envelopes
and
dissipated to the ambient by a way of forward cooling that utilizes the
conducive
structures as well as the support block physically arranged and configured at
the front
portion of the light bulb rather than the back.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other features and advantages of the invention will be more
fully understood from the following descriptions of various embodiments of the
invention and the accompanying drawings. In the drawings like reference
numerals
generally refer to similar elements throughout. The drawings are not
necessarily to scale,
emphasis instead being placed upon illustrating the principles of the
invention.
FIG. 1 is a schematic illustration showing a common chandelier installed with
existing LED bulbs having back-side heat sinks and facing toward a ceiling;
FIG. 2 is a side view of an embodiment of an LED light bulb of the invention;
FIG.3 is an exploded view of an embodiment of the LED light bulb in FIG. 2;
FIG. 4 is an exploded view of another embodiment of the LED light bulb in FIG.
2;
FIG. 5 is an exploded view of another embodiment of the LED light bulb in FIG.
2;
FIG. 6 is a side view of an embodiment of an LED light bulb of the invention;
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FIG. 7A is a side view of an embodiment of a stem assembly of an LED light
bulb
of the invention;
FIG. 7B is a side view of another embodiment of a stem assembly of an LED
light
bulb of the invention;
FIG. 8 is a side view of another embodiment of an LED light bulb of the
invention;
FIG. 9 is an exploded view of an embodiment of the LED light bulb in FIG. 8;
FIG. 10 is a perspective view of another embodiment of an LED light bulb of
the
invention;
FIG. I l is an exploded view of an embodiment of an LED light bulb in FIG.10;
FIG. 12 is an exploded view of an embodiment of an LED light bulb in FIG. 10;
FIG. 13 is a side view of an LED light bulb in FIG. 10 in an upright position;
FIG. 14A shows a plan layout of an LED light source;
FIG. 14B shows another plan layout of an LED light source;
FIG. 14C shows another plan layout of an LED light source; and
FIG. 15 shows a schematic perspective view of an LED stem assembly.
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DESCRIPTION OF EMBODIMENTS OF THE INVENTION
An LED light bulb of the present invention is compatible with existing sockets
for
incandescent, filament or fluorescent light bulb. According to one embodiment
of the
present invention as shown in FIG. 2 and 3, an LED light bulb 10 comprises a
shell 20
having an inner space 23 enclosed by a light transmissive upper envelope 22
and a
lower sealing member 26 along a central axis A; an axially extending,
thermally
conducive stem assembly 30 comprising a first conductive structure 32 and a
second
conductive structure 36 attached to opposite sides 37, 39 of a support block
34; said first
conductive structure 32 extending toward the upper envelope 22 and said second
conductive structure 36 extending toward the lower sealing member 26 and
attached
thereto along the central axis A of the shell 20; an LED light source 40
arranged and
mounted on said support block 34 of the stem assembly 30, comprising a
plurality of
LEDs 43, 45 centralized around a center C of the support block 34 and
including a first
light emitting side 42 and a second light emitting side 46 facing toward the
upper
envelope 22 and the lower sealing member 26 of the shell 20 respectively to
provide up
and down lights along the first and second conductive structures 32, 36 of the
stem
assembly 30 extending directly in front of the first and second light emitting
sides 42,
46 of the LED light source 40; and a base 50 attached to the shell 20 and
configured to
receive an internal circuitry 70 therein; said internal circuitry being
electrically
connected to the LED light source 40. The sealing member 26 may be joined or
sealed
to the upper envelope 22 by means of for example, thermal fusion or heat, or
adhesives.
The base 50 may further comprise an end cap 90, such as an Edison/contact
socket. In
addition, the base 50 may further include a flange 56 to be attached to an
opening of the
upper envelope 22 of the shell 20, preferably beneath the sealing member 26 of
the shell
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20, by means of for example, adhesives, fastening threads and so forth.
The first and second light emitting sides 42, 46 of the LED light source 40
are
preferably on a plane substantially perpendicular to the central axis A of the
shell 20
such that up and down lights may be provided directly toward the upper
envelope and
the lower sealing member 22, 26 of the shell 20 along the first and second
conducive
structures 32, 36 of the stem assembly 30 disposed in front of the light
emitting sides 42,
46 of the LED light source 40. A first LED module 43 of the LED light source
40 may
include first light emitting side 42 facing toward the upper portion 22 of the
shell 20 and
a second LED module 45 may include the second light emitting side 46 facing
toward
the lower portion 26 of the shell 20; wherein the first and second modules 43,
45 may
comprise a plurality of LEDs or emitters soldered onto substrates 47, 49 and
arranged to
centralize and surround the center C of the support block 34. In addition, it
is preferably
that the LED light source 40 may further comprise side-view LEDs or emitters
41
having a lateral light emitting side 44 on a plane substantially parallel to
the central axis
A of the shell 20 and facing toward a side of the shell 20 to provide lateral
lights.
In one embodiment, the first conductive structure 32 of the stem assembly 30
comprises an elongated column axially extending away from support block 34
toward
the upper envelope 22 of the shell 20. The second conductive structure 36 of
the stem
assembly 30 comprises an axially extending column, preferably a hollow column,
attached to one protruded end 24 of the lower sealing member 26 of the shell
20. The
first and second conducive structures 32, 36 may effectively conduct the heat
generated
by the LED light source 40 away from the support block 34 by a way of forward
cooling to the front of the light source 40, and particularly to the front of
the light
emitting sides 42, 26. While utilizing said first and second conductive
structures 32, 36
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of the stem assembly 30, the shell 20 and the inner space 23 of the shell 20
in the front
portion of the light bulb 10, the light bulb 10 may effectively dissipate the
heat to the
ambient via for example, heat radiation, conduction and/or convection of an
internal gas
in the inner space 23 as well as the circumferential surface of the shell 20
as a whole. In
another embodiment, the first and/or second conducive structure 32, 36 of the
stem
assembly 20 may too include a heat pipe envelope or structure extending away
from the
support block 34 to facilitate the heat dissipation away from a hot end or
heat source
(light source) to a cooler end near the shell away from the heat source.
In terms of the means of attachment and securement of parts, the support block
34
of the stem assembly 30 may further comprise a center mounting hole 38 to
receive a
portion 33, 35 of the first conductive structure 32 and second conductive
structure 36
attached thereon. The support block 34 of the stem assembly 30 may be further
provided with a threaded portion 38' preferably at an inner surface of the
center
mounting hole 38 to fasten said the ends 33, 35 of the first and/or second
conducive
structures 32, 36 attached thereon. It can be understood that the first and
second
conductive structure 32, 36 may be affixed to the support block 34 to form a
stem
assembly 30 by means of for example, adhesives, press-fitting, fixations such
as screws
and bolts and so forth; in addition, the stem assembly 30 may too be
integrally formed
as one piece by means of for example, thermal fusion by heat or molding, such
as
injection or rotation molding.
FIG. 4 and 5 depict further explanatory variations and embodiments of an LED
light bulb 10 of the invention. As mentioned previously, the first and second
conductive
structures 32, 36 of the stem assembly 30 may be integrally formed as one
piece of an
elongation. According to one embodiment of the present invention as shown in
FIG. 4,
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the second conductive structure 36 of the stem assembly 30 may be joined to
the lower
sealing member 26 as well as the base 50, which may too be integrally formed
as one
piece. It may be preferably that the stem assembly 30 is joined to the base 50
via the
sealing member 26 and integrally formed. The support block 34 onto which the
LED
light source is mounted may be attached to the conductive structures 32, 36 by
means of
for example, fastening threads 38' and/or adhesives, press-fitting, fixations
such as
screws and bolts. FIG. 5 shows another embodiment in which the first
conductive
structure 32 extending away from the support block 34 may be joined to a top
portion
21 of the upper envelope 22 of the shell 20 by means of for example,
adhesives,
fixations such as screws and bolts and so forth; it may too be preferably that
the first
conducive structure 32 and the upper envelope 22 are integrally formed by
means of for
example, molding or thermal fusion by heat. As the first and second conducive
structures 32, 36 may be integrally formed as an elongated column, the support
block 34
may also be further secured to conducive structures via for example, fastening
threads
38'. Such explanatory variations in structure and configuration are provided
as
examples to demonstrate possible embodiments of the invention having a reduced
or
combined number of separated parts for a reliable and cost-effective design in
terms of
for example, material and manufacturing costs. It too can be understood that
the first
and second conductive structures may be of other shapes and configurations of
elongated bodies including winding, spirals and so forth.
Additionally, the stem assembly 30 may further comprise at least one
perforation
31 fluidly connected to the inner space 23 of the shell 20. The sealing member
26 may
be joined to the upper envelope 22 of the shell at an inner space or a bottom
portion 28
thereof, making the inner space 23 an airtight closure. The inner space 23 of
the shell 20
may be evacuated to contain at least a partial vacuum and/or filled with a
high thermal
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conductive medium or internal gas such as helium, argon, nitrogen, carbon
dioxide,
hydrogen, metal halides and mixtures thereof, preferably via a perforation 29
formed on
the lower sealing member 26 of the shell 20 or via the perforations 31 formed
on the
stem assembly 30 such that heat dissipation is enhanced by the
conduction/convection
of the internal gas. In another embodiment, a shear thickening fluid with the
property of
increased viscosity in relation to the rate of shear or having a significant
increase in the
resistance to flow while subject to a sudden impact on its surface such as, a
silicon oil
solution with a non-conducive particle of starch suspensions, may be filled
into the
inner space 23 of the shell 20 to enhance heat dissipation via fluid
conduction/convection and to prevent sudden leakage of the fluid upon
accidental
impacts to the bulb. Additionally, an electric connector 48, such as lead
wire, is
provided to form part of the electrical connection between the first and
second LED
modules 43, 45 of the LED light source 40. Said perforations 31 may too
facilitate
electrical connectors 58, such as lead wires, from the base 50 to pass
therethrough to
connect to the LED light source 50.
FIG. 6 shows another embodiment of an LED light bulb 100 of the present
invention; wherein the first and second conductive structures 132, 136 of the
stem
assembly 130 may comprise a plurality of axially extending fins attached to
the support
block 134 and radiating away from the center C of the support block 134. It is
preferably that the first and second conducive structures 132, 136 may be
joined as
elongated bodies of fins having one end extending toward the top portion of
the upper
envelope 122 of the shell 120 and the other end extending toward the lower
sealing
member 126 of the shell 120 and attached thereto via a fixation collar 160.
The support
block 134 and the fixation collar 160 may further comprise a plurality of
slots 161 to
receive and secure the first and/or second conductive structures 132, 136
thereon. The
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LED light source 140 may include first and second LED modules 143, 145, having
first
and second light emitting sides 142,146 facing toward the upper envelope 122
and the
lower sealing member 126 of the shell 120 respectively. It is also preferably
to include
side-view LED emitters 141 to provide lateral lights in addition to said up
and down
lights. The base 150 may further include an end cap 190, such as an
Edison/contact
socket, electrically connected to the internal circuitry 170 enclosed therein.
FIG. 7A and 7B shows further explanatory embodiments of a stem assembly 130
comprising variations and combinations of first and second conducive
structures. In a
further embodiment as shown in FIG. 7A, a stem assembly 130 for an LED light
bulb of
the invention comprises a first conductive structure 132 of an elongated
column
extending away from the support block 134 and a second conducive structure 136
of a
plurality of fins radiating away from the support block 134 and attached to
corresponding slots 161 of a fixation collar 160 on one protruded end of a
sealing
member 126. Likewise FIG. 7B shows another embodiment of a stem assembly 130
having a reversed first and second conductive structures 132, 136 of the ones
of FIG. 7A.
The first conducive structure 132 extending away from the support block 134
and
toward the top portion may be a plurality of fins attached to the support
block 134 with
slots (not shown); whereas the second conductive structure 136 may be an
elongated
column extending away from the support block 134 and attached to a protruded
end 124
of the sealing member 126. The LED light source 140 includes a first LED
module 143
having a first light emitting side 142 facing away from a second light
emitting side 146
of a second LED module 145. The first and second LED modules 143, 145 may be
of
dissimilar (or similar) output powers or arrangements while providing up and
down
lights from said light emitting sides 142, 146 in a direction along said first
and second
conducive structures 132, 136 of the stem assembly 130.
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According to another embodiment of the present invention as shown in FIG. 8
and
9, an LED light bulb 200 comprises a shell 220 having an inner space 222
enclosed by a
light transmissive upper envelope 226 and a lower sealing member 226 along a
central
axis A; an axially extending, thermally conducive stem assembly 230 comprising
a first
conductive structure 232 and a second conductive structure 236 attached to a
first
surface 237 and a second surface 239 of a support block 234; wherein the first
surface
237 is preferably to be directly opposite to the second surface 239. The first
conductive
structure 232 extends toward the upper envelope 222; whereas, the second
conductive
structure 236 extends toward the lower sealing member 226 and is attached to a
protruded end 224 thereof along the central axis A of the shell. The first
conductive
structure 232 may be further joined to a top portion 221 and the lower sealing
member
126 may further joined to a bottom portion 228 of the upper envelope 222. The
LED
light bulb 200 also comprises an LED light source 240 arranged and mounted on
said
support block 234 of the stem assembly 230; said LED light source 240 includes
a first
LED module 243 and a second LED module 245 configured around a center C of the
support block 234, having a first light emitting side 242 and a second light
emitting side
246 facing toward the upper envelope 222 and the lower sealing member 226 of
the
shell 220 respectively to provide up and down lights along the first and
second
conductive structures 232, 236 of the stem assembly 230 extending directly in
front of
the light source 240 and particularly, in front of the light emitting sides
242, 246. A
connection mans 248, such as lead wire, may be further provided, forming part
of the
electrical connection between the first and second LED modules 243, 245 of the
LED
light source 240. The sealing member 226 may be sealed to the bottom portion
228 of
the upper envelope 222 by means of for example, thermal fusion or heat, or
adhesives.
An inert or dielectric base 250 configured to receive an internal circuitry
270 therein is
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attached to the bottom portion 228 of the shell 220; wherein the internal
circuitry 270 is
electrically connected to the LED light source 240 via for example, lead wires
258 from
the bases 250. The base 250 includes an end cap 290, such as an Edison/contact
socket,
electrically connected to the internal circuitry 270 enclosed therein.
The LED light source 240 may be arranged and configured to surround the center
C of support block 240 to provide both up and down lights. In addition, the
first and
second light emitting sides 242, 246 of the first and second LED modules 242,
246 of
the LED light source 240 mounted on opposite sides 237, 239 of the support
block 240
are preferably to be on a plane substantially perpendicular to the central
axis A of the
shell 220. In one embodiment, the first and second LED modules 243, 245
comprising a
plurality of LEDs may be in a form of LED rings. The first and second LED
rings 243
and 245 may be formed on ring-shaped substrates surrounding the center C of
the
support block 234 as for example, multi-chip modules on PCB or MCPCB (metal
core
PCB) utilizing flip-chip packaging technology or chip on board (COB) or
surface mount
technology (SMT) connecting a plurality of LEDs to form an area light source.
In addition, it may be preferable that the first and second LED rings 243, 245
are
formed of dissimilar diameters away from the center C of the support block 234
to
avoid overlapping the LED rings on opposite sides 237, 239 of the support
block 234
for a uniform distribution of heat on the support block 234. For example, the
first LED
ring 243 may be an inner ring having an outer diameter Dl_ont and an inner
diameter
Di-in, capable of providing up lights while the second LED ring 245 may be an
outer
ring having an outer diameter D2,,,t and an inner diameter 132-in capable of
providing
down lights; in one instance, Dl-o,,t of the first LED ring 243 may be less
than or equal
to D2_in (D1-out D2-in) and another example such as, D2- ,t < D1_in is also
possible.
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The stem assembly 230 comprises first and second thermally conducive
structures
232, 236 extending away from the support block 234. In one embodiment, the
first
conductive structure 232 of the stem assembly 230 may comprise an elongated
column
axially extending away from support block 234. It may too be preferable that
the first
conductive structure 232 of the stem assembly 230 extends toward the upper
envelope
222 of the shell 220 and joined to a top portion 221 of the upper envelope 222
of the
shell 220 to conduct heat originated from the LED light source 240 away from
the
support block 234 toward the top portion 221 of the shell 220 and subsequently
the
circumferential surface area of the shell 220 as a whole for heat dissipation
to the
ambient. The second conductive structure 236 of the stem assembly 230 may too
comprise an axially extending column, preferably a hollow column, attached to
one
protruded end of said sealing member 226. In a further embodiment, the heat
from the
LED light source 240 may be conducted away from the support block 234 to the
shell
220 via both the upper and lower portions 222, 226 of the shell 220 via the
top potion
221 and bottom portion 228 joined to the conductive structures 232, 236 of the
stem
assembly 230 such that the heat is transmitted to the entire circumferential
surface of the
shell 220 for dissipation to the ambient. As the first conductive structure
232 extending
toward the upper envelope 222 of the shell 220 is joined to the top portion
221 and the
lower sealing member 226 of the shell 220 onto which the second conducive
structure
236 is attached is further sealed to the bottom portion 228 of the upper
envelope 222,
heat from the LED light source 240 is effectively and efficiently conducted
away from
via the first and second conductive structures 232, 236 to the shell for heat
dissipation.
Similarly, the heat dissipation may be further enhanced by an internal gas or
fluid
filled into the inner space 223 of the shell 220 of an LED light bulb 200 of
the present
invention. In one embodiment, the stem assembly 230 further comprises a
perforation
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231 fluidly connected to the inner space 223 of the shell 220. As the sealing
member
226 may be joined to the upper portion 222 of the shell 220, making the inner
space 223
an airtight closure, the inner space 223 of the shell 220 may then be
evacuated to
contain at least a partial vacuum, which may also be filled with a high
thermal
conductive medium or internal gas such as helium, argon, nitrogen, carbon
dioxide,
hydrogen, metal halides and mixtures thereof, via a perforation 229 formed on
the lower
sealing member of the shell or the perforation 231 formed on the stem assembly
230.
The heat may then be further dissipated by way of for example,
conduction/convection
of said internal medium and subsequently via the shell 220 to the ambient. As
mentioned previously, in another embodiment, a shear thickening fluid with may
too be
filled into the inner space 223 of the shell 220. The perforation 231 may too
facilitate
electrical connectors such as lead wires 258 from the base 250 to pass
therethrough to
the LED light source 250.
The base may be configured to receive an internal circuitry in accordance with
the
types of LEDs used, including for example, direct current (DC) and alternate
current
(AC) LEDs. As shown in FIG. 8 and 9, in one embodiment, the LED light source
240
may be an AC LED module such that the dimension of the base 250 of the light
bulb
200 may be reduced to include electronic component(s) such as resistor,
capacitor
and/or positive temperature coefficient (PTC) thermistor. For DC LED light
source of
an LED light bulb of the present invention, the base of the light bulb may
include an
internal circuitry having a power supply, AC/DC-converter, driver and/or
bridge.
According to still another embodiment of the present invention as shown in
FIG.
and 11, an LED light bulb 300 having a dual lighting including an upper
lighting part
and a lower lighting part is capable of providing a uniform illumination
including at
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least up and down lights from an LED light source 340 with an effective
forward
cooling. As the support block 343 onto which the LED light source 340 may be
mounted is physically positioned at a front portion of the light bulb 300 a
distance away
from the base 350, heat dissipation via the front may be facilitated in
addition to the fact
that the heat is also being conducted away from the support block 334 directly
to the
front of the light emitting sides 342, 346 of the LED light source 340 rather
to the back.
In one embodiment of the LED light bulb 300, the LED light bulb 300 comprises
a light transmissive upper envelope 322 having an enclosed top portion 321 and
a
bottom opening 324 along a central axis A; a light transmissive lower envelope
326
having a top opening 325 and a bottom portion 328, arranged away from the
bottom
opening 324 of the upper envelope 322 along the central axis A thereof. A
support block
334 is further provided and includes a first side 337 attached to the bottom
opening 324
of the upper envelope 322 to enclose an upper inner space 323 and a second
side 339
attached to the top opening 325 of the lower envelope 326. Said first side 337
of the
support block 334 further comprises a first conducive structure 332 extending
toward
the top portion 321 of the upper envelope 322 and said second side 339 further
comprises a second conducive structure 336 extending toward the bottom portion
328 of
the lower envelope 326.
The support block 334 is preferably configured and arranged to be at a front
portion of the LED light bulb 300. In one embodiment, the support block 334
having an
diameter Ds may be positioned at the front portion of the LED light bulb 300
and a
distance or height H away from an end 356 of the base 350 and wherein the end
356 is
attached to the lower envelope 326 such that said Ds may be substantially
equivalent to
or greater than a bulb diameter DB of the light bulb 300; wherein the bulb
diameter DB
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refers to the diameter of the largest cross sectional area of the light bulb
300. As shown
in FIG. 11 and 12, said H may too refer to height of said lower envelope 326.
In another
embodiment, said distance H of the support block 334 positioned on top of the
lower
envelope 326 may be at least greater than or equal to 1/2 of the total length
L of the
LED light bulb 300 and preferably, said H may be of 2/3 of the total length L
of the bulb.
Furthermore, the bottom opening 324 of the upper envelope 322 and the top
opening
325 of the lower envelop 326 may too be of diameters substantially equivalent
to the Ds
of the support block 334. In a further embodiment, the support block 334 may
be
configured and positioned at a height H greater than or equal to 4/5 of the
total length L
of the bulb 300 such that Ds of the support block 334 may be less than said
bulb
diameter DB. In addition, the thickness Ts of the support block 334 may be
suitably
selected in accordance with the height H to allow optimal heat dissipation as
well as up
and down lights. It can be understood that the upper and lower envelopes 322,
326
together with the support block 334 may form a bulb shape according to various
standards including A/G/PS type bulbs.
As shown in FIG. 10 and 11 again, the LED light bulb 300 further comprises an
LED light source 340, which may be for example, AC or DC LED module(s) as
previously mentioned. The LED light source 340 further comprises a first LED
module
343 and a second LED module 345 arranged and mounted on said first and second
sides
337, 339 of the support block 334 respectively; wherein said first LED module
343
having a first light emitting side 342 facing toward the top portion 321 of
the upper
envelope 322 to provide up lights along the first conductive structure 332
extending
directly in front of the first light emitting side 342, and said second LED
module 345
having a second light emitting side 346 facing toward bottom portion 328 of
the lower
envelope 326 to provide down lights along the second conductive structure 336
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extending directly in front of the second light emitting side 346. In
addition, to provide
direct up and down lights, the first and second light emitting sides 342, 346
of the first
and second LED modules 343, 345 may preferably be on a plane substantially
perpendicular to the central axis A of the upper envelope 322. A connection
means, such
as lead wire 348, may be further provided to connect the LED modules 343, 345.
According to one embodiment of an LED light bulb 300 of the present invention,
various shapes of the first and second conducive structures 332, 336 and the
support
block 334 disposed therebetween may form a stem assembly 330. In one
embodiment,
the first conductive structure 332 may be an axially extending column, and the
second
conductive structure 336 may too be an axially extending column, preferably a
hollow
column. The first and second conducive structures 332, 336 may be attached to
the
support block 334, preferably at the center C of the support block 334 by
means of for
example, fastening threads, adhesives, fixations such as screws and bolts and
so forth.
Furthermore, it can be understood that the first and second conductive
structures 332,
336 may be of different configurations of elongated bodies including radiating
fins as
mentioned previously or winding, spirals and so forth.
Furthermore, an inert or dielectric base 350 may be attached to the bottom
portion
328 of the lower envelope 326 on one end 356 to enclose a lower inner space
329 of the
lower envelope 326 and may too be configured to receive an internal circuitry
370
therein; the internal circuitry 370 is also electrically connected to the LED
light source
340. As shown in the figures, in one embodiment, the base 350 may further
comprise a
sealing member 352 joined to the bottom portion 328 of the lower envelope 326
and
attached to one end of the second conducive structure 336 of the support block
334 by
means of for example, thermal fusion or heat, or adhesives. To facilitate the
electrical
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connections such as lead wires 358 from the base 350 to the LED light source
340, the
support block 334 may also include an opening P connecting both upper and
lower inner
spaces 323, 329 of the envelopes; it may too be a cut-out or notch on an edge
portion of
the support block 334 fluidly connected to both sides 337, 339 thereof. The
opening P
may too facilitate electrical connectors 358 such as, lead wires from the base
350 to pass
therethrough to the LED light source 340. The base 350 further includes an end
cap 390
such as, an Edison/contact socket, electrically connected to the internal
circuitry 370.
The upper and lower inner spaces 323, 329 of the upper and lower envelopes
322,
326 may be evacuated to contain at least a partial vacuum and/or filled with a
high
thermal conductive medium selected from any one of the following gases:
helium,
argon, nitrogen, carbon dioxide, hydrogen, metal halides and mixtures thereof.
The
evacuation of air and filling of an internal gas may be achieved via
perforations 331
provided on the stem assembly 330 or the second conducive structure 336.
Furthermore,
in another embodiment, the upper and lower inner spaces of the upper and lower
envelopes may be filled with a shear thickening fluid as mentioned previously
to
enhance heat dissipation via fluid conduction/convection and to prevent sudden
leakage
of the fluid upon sudden impacts to the bulbs.
FIG. 12 shows another embodiment of an LED light bulb 300 of the present
invention. The upper and lower envelopes 322, 326 may be integrally formed
with the
first and second conducive structures 332, 336 respectively of a material
selecting from
any one of the following: transparent ceramics, glass and silicon based
material. The
first conducive structure 332 may be joined or attached to the top portion 321
of the
upper envelope 322 and may preferably be formed as one piece by means of for
example, molding or thermal fusion by heat. Similarly, the second conducive
structure
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336 may be joined or attached to the bottom portion 328 of the lower envelope
326 and
preferably be formed together with the abovementioned sealing member 356 as
one
piece. A fastening threaded portion 338 may too be provided on the portions of
the
conductive structures and the support block 334 for securement thereto. The
heat from
the LED light source 340 may then be conducted away from the support block 334
toward both the top and bottom of the envelopes 322, 326 via the first and
second
conducive structures 332, 336 and subsequently utilizing the entire surface of
the
envelopes and structures at the front portion of the light bulb for forward
cooling to
dissipate the heat to the ambient effectively and efficiently.
In one embodiment, an outer ring 380 may be further provided on the light bulb
300 and preferably surrounding or enclosing the outer circumferential surface
of the
support block 334. The outer ring 380 may be of an inner diameter DR
substantially
equivalent to abovementioned Ds of the support block 334. The outer ring 380
may be
made of a dielectric material as a safety measure to prevent possible leakage
of current
from the LED light source 340 to the support block 334. The outer ring 380 may
too be
of a material of relatively good thermal conductivity to facilitate the heat
dissipation
away from the support block 334 to the ambient; for example, the outer ring
380 may be
made of a ceramics and/or transparent ceramics.
FIG. 13 is explanatory illustration showing heat dissipation from an LED light
source of an LED light bulb in an upright position. As shown by the "arrows"
in FIG. 13,
heat generated by the LED light source 340 during operation may be dissipated
via
conduction Cc, convection Cv of an internal gas and radiation CR. By means of
conduction CC, the heat is conducted away toward the shell body 320 comprising
an
upper envelope 322 and a lower envelope 326, via the thermally conductive
structures
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332, 336 extending in front of the light source 340. As heat tends to travel
in an upward
direction (relative to the ground), the first and second conductive structures
332, 336
provide an effective conduction means allowing the heat to be transmitted away
from
the heat source (light source) toward the shell 320 and subsequently utilizing
the entire
surface thereof, preferably including the circumferential surface of the
support block
334, for further dissipation to the ambient via the front portion of the light
bulb that may
be oriented in an upright or upside-down position. It may be preferably that
the tips or
ends 333, 335 of the first and second conductive structures 332, 336 are
joined to the
upper and lower portions of the envelopes 322, 326 of the shell 320 to
facilitate the heat
conduction to the front portion of the light bulb including the structures and
the shell as
a whole. As mentioned previously, the inner front spaces 323, 329 may too be
filled
with an internal gas G of high thermal conductivity to enhance heat
dissipation via
convection Cv in addition to the heat radiation CR away to the ambient via the
shell 320.
FIG. 14A -14C show further details of an LED light source according to
embodiments of an LED light bulb of the present invention. As mentioned
previously,
the LED light source may be either DC or AC LED module; For DC LED modules ,
the
internal circuitry in the base may include power supply, AC/DC-converter,
driver and/or
bridge; whereas for AC LED modules, the internal circuitry may including
component(s)
such as resistor, capacitor and/or positive temperature coefficient (PTC)
thermistor. As
shown in the figures, "a, b, c, c', d, e" may refer to electrodes and may be
connected in
series with "a" and "e" attached to an internal circuitry of an LED light
bulb.
FIG. 14A is an explanatory circuit layout of an embodiment of an LED light
source
40. The right and left sides of the figure refer to first and second modules
43, 45 of an
LED light bulb of the invention ("up" toward the upper portion of the shell;
"down"
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toward the lower portion thereof). As shown on the right, a first LED module
43
comprising a plurality of LEDs or LED emitters may be affixed to a first
substrate
47and electrically connected to each other, preferably in series; likewise,
the left shows
a second LED module 45 affixed to a second substrate 49. The LED modules may
be
multi-chip modules on PCB or MCPCB utilizing flip-chip packaging technology or
may
be provided via chip on board or surface mount technology. The LED emitters
are
arranged preferably to be centralized and surrounding the center C (or around
the
abovementioned central axis A of the shell 20) on the first and second
substrates 47, 49
of the LED modules 43, 45. It may be preferable that the LEDs are arranged
spaced
apart in an alternate manner such that they may not directly overlap in a
longitudinal or
vertical direction on the opposite sides of the support block. Additionally,
side-view
LEDs or emitters 41 may be further provided surrounding the center C. It can
be
understood that the first LED module 43 and the second LED module 45 may be
axially
symmetrical having the same power; e.g. each of the first and second modules
43, 45 is
a 4.2W module consisting of three I W LED emitters and six 0.2W side-view LED
emitters in series and further connected to each other, preferably in series,
to provide an
LED light source 40 with a total output power of 8.4W. In another example, the
first and
second LED modules are connected in parallel to produce a designed or desired
output;
furthermore, the first and second LED modules may too be of dissimilar powers.
FIG. 14B shows an LED light source 340 according to another embodiment of an
LED light bulb of the invention. The LED light source 340 comprising a
plurality of
LEDs or emitters affixed on a first substrate 347 and a second substrate 349
to form a
first LED module 343 (right) and a second LED module 345 (left) to provide up
and
down lights respectively may preferably be centralized around the center C in
an
alternate manner. The first LED module 343 and the second LED module 345 may
be
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CA 02687529 2009-12-03
axially symmetrical to be of the same power; e.g. each of the first and second
modules
343, 345 is a 5W module consisting of a plurality of LED emitters all in
series to
provide an LED light source 340 with a total output power of 10W. It can be
understood
that the first and second LED modules may too be connected in parallel
depending on
the desired output; in another example, they may be of dissimilar powers, e.g.
the first
module 343 is a 6W module and whereas the second module 45 is a 4W module
together forming a lOW LED light source 340.
FIG. 14C shows another embodiment of an LED light source 540 includes a
plurality of LEDs electrically connected to each other on substrates 547 and
549 to form
a first LED ring 543 (right) and a second LED ring 545 (left) surrounding the
center C;
wherein the first LED ring and a second LED ring are formed of dissimilar
diameters
away from the center of the support block. The first and second LED rings 543,
545
may preferably be provided as an area light source and for example, multi-chip
modules
on PCB or MCPCB utilizing flip-chip packaging technology or may be provided
via
chip on board or surface mount technology. For an even distribution of heat
during
operation of the LED light source 540, in one embodiment, the first LED ring
543 may
be of an inner diameter D1, and the second LED ring 545 may be of an outer
diameter
D2 such that in one embodiment, D1 may be less than or equal to D2 (i.e. Dl
<D2) as
mentioned previously. The first and second LED rings 543, 545 may be axially
symmetrical modules packaged to be of the same power; e.g. they may each be a
5W
LED ring connected in series to provide an output of lOW; or in parallel for a
total
output of 5W; in still another embodiment, the first and second LED rings 543,
545 may
be modules of dissimilar powers.
Furthermore, the support block of the stem assembly onto which the LED light
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source is mounted may be of various shapes and forms, comprising a plurality
of
surfaces joined to form any one of the following shapes of: disc column, cube,
pyramid
and diamond. FIG. 15 shows an LED light source 640 according to a further
embodiment of an LED light bulb of the present invention. The LED light source
640
may too be attached to a support block 634 of a geometric shape having
multiple
surfaces, such as a diamond-like shape. A number of first and second
substrates 647,
649 may be mounted and connected on the supporting block 634. Again, the LEDs
on
the first and second substrates 647, 649 may be provided as a plurality of
area light
sources formed by means of for example, multi-chip LED modules on PCB or MCPCB
utilizing flip-chip packaging technology or may be provided via chip on board
or
surface mount technology. A stem assembly 630 having a plurality of thermally
conductive structures 632 in a form of such as plates or tubes may extend away
from the
center C of the supporting block 634 toward a bulb shell. It can be understood
that other
shapes are possible such as cube, sphere and so forth.
The materials disclosed herein are for illustrative purposes and aimed to
facilitate
the realization of various explanatory embodiments of the present invention
only, which
shall not be treated as limitations to the present invention.
The shell or envelope of an LED light bulb of the present invention may be
formed
of a transparent material with or without surface treatment. The transparent
material of
the shell may include glass, silicon based material, plastic, or transparent
ceramics such
as transparent alumina (A12O3). An example of a transparent ceramic is
provided by
General Electric Company (GE) and marketed as Lucalox ceramic, a
polycrystalline
translucent aluminum oxide ceramic. The Lucalox ceramic is hard and capable
of
withstanding to a high pressure (25, 000 psi) and melting point (1800 Q. It
also
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exhibits high dielectric strength as insulation. The Lucalox ceramic is also
capable of
transmitting a wide spectrum of wavelengths including visible spectrums. The
thermal
conductivity of Lucalox ceramic is found to be equally good or better than
some
metals. While subject to heat, the ceramic also shows a relatively uniform
thermal
expansion in all directions. The shell may also be of various forms and shapes
according
to different standards including, A/G/PS type bulbs and tubular bulbs. In one
embodiment, the outer surface of the shell may be further treated or coated
with surface
irregularities to reflect, refract and/or deflect lights for a more uniform
light distribution.
The stem assembly including the conductive structures and support block may
too
be made of materials of high or relatively good thermal conductivity, for
example,
ceramic, carbon composite, metal or metal alloy and a combination thereof, to
facilitate
the heat transferred from the LED light source. It may also be preferable that
the
conductive structures are made of a dielectric material such that it acts as
an insulation
to prevent reaction with an internal gas and/or to prevent possible electric
leakage
conducted from the LED. light source or the supporting block; in one example,
the
thermally conductive material is a ceramic with good thermal conductivity such
as
aluminum nitride (A1N). It may too be preferable that the conductive
structures are
made of transparent ceramics, such as the abovementioned Lucalox ceramic from
GE.
In another embodiment, carbon composites may too be used for the stem assembly
including thermally conducive structures. One further advantage to the use of
carbon
composites is that they are structurally destructible under certain impacts
such that the
elongated bodies of the conductive structures may not physically endanger
others and
the environment as sharpened objects, especially in the case of accidental
breakages of
the bulb from a height. In another embodiment, the stem assembly and the
conductive
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CA 02687529 2009-12-03
structure may too be formed of a metallic material such as copper, aluminum
and so
forth, with high thermal conductivity. In still a further embodiment, the
conductive
structures of the stem assembly may also comprise heat pipe envelope(s), such
as heat
pipe or flat plate heat pipe, attached to the supporting block as mentioned
previously.
Furthermore, the outer surface of the conductive structures of the stem
assembly may be
coated with a thin reflective film on the surface thereof to enhance light
reflection rather
than absorption. The inner surface of hollow columns of conductive structures
of the
stem assembly, on the other hand, may be coated with a dielectric film to
prevent
possible leakages of current from the light source and/or lead wires.
As shown in various embodiments of an LED light bulb of the present invention,
parts and elements of the LED light bulb may be integrally formed as one piece
of a
material. In one embodiment, the stem assembly including the conductive
structures and
the support block may be integrally formed by means of for example, molding
including
injection, rotation molding and so forth. Likewise, in another embodiment, the
shell and
the conductive structures of the stem assembly may be integrally formed.
Furthermore,
the base may be formed of a dielectric material such as plastic with a metal
Edison
contact socket as the end cap.
According to one embodiment of an LED light bulb of the present invention, an
outer ring may be further provided on the light bulb and preferably
surrounding or
enclosing the outer circumferential surface of the support block. The outer
ring may be
made of a metal or metal alloy to assist heat transfer; it may too be a
dielectric material
such as ceramics or transparent ceramics to provide better safety measures to
prevent
possible leakage of current from the LED light source to the support block.
The ring
may also be further coated with paints and/or markings for decorative
purposes.
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As the inner space of the shell may be evacuated to contain at least a partial
vacuum and filled with an internal gas or fluid of relatively high thermal
conductivity to
enhance heat dissipation, in one embodiment, said internal gas or medium may
be
selected from any one of the following: helium, argon, nitrogen, carbon
dioxide,
hydrogen, metal halides and mixtures thereof such that the heat may be
transferred via
conduction/convection of the internal gas to the shell and to the ambient; and
in another
embodiment, the filled fluid may be a shear thickening fluid such as a silicon
oil with
non-conductive suspensions including for example, starch to also prevent
sudden
leakages of fluids under impacts to the light bulb. The non-conductive
suspensions in
the fluid may too be nano-sized to prevent aggregations and precipitation of
these
particles over time.
The claims in the subsequent content should not be read as limitations to the
described order or elements unless stated to that effect. While the invention
has been
particularly shown and described with reference to specific illustrative
embodiments, it
should be understood that various changes in form and detail may be made
without
departing from the spirit and scope of the invention as defined by the
appended claims.
Furthermore, as an example, any of the disclosed features may be combined with
any of
the other disclosed features to form a stem assembly for an LED light bulb
with or
without a base and/or shell attached thereon in accordance with the invention;
a
supporting block may too refer to a portion on a thermal conductive structure
for the
attachment of an LED light source and may be with or without substrates in
accordance
with the invention. Therefore, all embodiments that come within the scope and
spirit of
the following claims and equivalents thereto are claimed as the invention.
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