U.S. patent application number 13/815914 was filed with the patent office on 2013-10-03 for system and method for mixing light emitted from an array having different color light emitting diodes.
The applicant listed for this patent is Lumenetix, Inc.. Invention is credited to Matthew D. Weaver.
Application Number | 20130258699 13/815914 |
Document ID | / |
Family ID | 49234801 |
Filed Date | 2013-10-03 |
United States Patent
Application |
20130258699 |
Kind Code |
A1 |
Weaver; Matthew D. |
October 3, 2013 |
System and method for mixing light emitted from an array having
different color light emitting diodes
Abstract
A method of manufacturing a light source includes providing a
substrate with electronic circuitry to drive light emitting diodes
(LEDs); coupling a plurality of LEDs to the electronic circuitry on
the substrate, the LEDs with more than one color types; and
attaching a mixing barrel around the plurality of LEDs over the
substrate, the mixing barrel with a reflective internal wall.
Inventors: |
Weaver; Matthew D.; (Aptos,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lumenetix, Inc. |
Scotts Valley |
CA |
US |
|
|
Family ID: |
49234801 |
Appl. No.: |
13/815914 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13367187 |
Feb 6, 2012 |
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13815914 |
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Current U.S.
Class: |
362/555 ;
362/231 |
Current CPC
Class: |
F21K 9/62 20160801; Y10T
29/49117 20150115; F21K 9/90 20130101; F21V 21/14 20130101; F21V
7/0066 20130101; G02B 6/0096 20130101; F21V 17/04 20130101; F21K
9/61 20160801; Y10T 29/49002 20150115 |
Class at
Publication: |
362/555 ;
362/231 |
International
Class: |
F21V 7/00 20060101
F21V007/00; F21V 8/00 20060101 F21V008/00 |
Claims
1. A point light source comprising: a substrate with electronic
circuitry to color tune light emitting diodes (LEDs); a plurality
of LEDs on the substrate coupled to the electronic circuitry, the
LEDs with more than one color types; and a mixing barrel around the
plurality of LEDs, the mixing barrel with a reflective internal
wall.
2. The point light source of claim 1, further comprising a diffuser
placed on the mixing barrel over an exit aperture of the mixing
barrel;
3. The point light source of claim 2, wherein the diffuser placed
over the mixing barrel is dome-shaped.
4. The point light source of claim 1, wherein the mixing barrel has
a smaller exit aperture away from the plurality of LEDs than a
source aperture around the plurality of LEDs.
5. The point light source of claim 1, wherein the mixing barrel is
conformal around the plurality of LEDs.
6. A point light source comprising: an electronic circuitry to
drive light emitting diodes (LEDs); a plurality of LEDs coupled to
the electronic circuitry, the LEDs with more than one color types;
a light pipe over the plurality of LEDs to provide total internal
reflection of light rays from the plurality of LEDs for light ray
angles larger than a critical angle with respect to a normal vector
of a surface of the light pipe; and a reflective wall around the
plurality of LEDs and around at least part of the light pipe.
7. The point light source of claim 6, further comprising a diffuser
optically coupled and bonded to the light pipe.
8. The point light source of claim 6, further comprising a diffuser
over the light pipe with an air gap therebetween.
9. The point light source of claim 6, wherein the light pipe has a
straight edge along a pipe axis of the light pipe and with rippled
patterned edges perpendicular to the pipe axis.
10. The point light source of claim 6, wherein the electronic
circuitry includes a color sensor within the reflective wall for
detecting a color profile from the plurality of LEDs.
11. The point light source of claim 6, wherein the electronic
circuitry includes a memory storage to store a color model of the
plurality of LEDs, the color model defining control signal to
achieve a particular color mixed from the plurality of LEDs at a
certain temperature.
12-34. (canceled)
35. A method of manufacturing a light source comprising: providing
a substrate with electronic circuitry to drive light emitting
diodes (LEDs); coupling a plurality of LEDs to the electronic
circuitry on the substrate, the LEDs with more than one color
types; and placing a light pipe on the plurality of LEDs to provide
total internal reflection of light rays from the plurality of LEDs
for a particular range of light ray angles.
36. The method of claim 35, further comprising attaching a mixing
barrel around the plurality of LEDs over the substrate, the mixing
barrel with a reflective internal wall.
37. The method of claim 35, further comprising patterning the light
pipe by removing parts of the light pipe.
38-49. (canceled)
50. The point light source of claim 6, further comprising a
diffuser that is an integral surface of the light pipe.
51. The point light source of claim 6, wherein the plurality of
LEDs is optically bonded to the light pipe via a silicone gel.
52. The point light source of claim 6, wherein the reflective wall
is a coating on an exterior surface of the light pipe.
53. The point light source of claim 6, wherein the reflective wall
is a chamber with a reflective inner surface around the light pipe,
the chamber separated from the light pipe.
54. The point light source of claim 6, wherein the light pipe has a
different source aperture size around the plurality of LEDs than an
exit aperture size on an opposite end of the light pipe
thereacross.
55. The point light source of claim 6, further comprising a
substrate with a reflective surface; wherein the plurality of LEDs
is on the reflective surface.
56. The point light source of claim 6, further comprising a low
angle reflector around the plurality of the LEDs and around the
light pipe, wherein a reflector angle of the low angle reflector
ensures total internal reflection within the light pipe
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 13/367,187, filed on Feb. 6, 2012, which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] Light emitting diodes (LEDs) that emit at different
wavelength bands can be used together to provide light that has a
desired color temperature, for example, simulating a particular
light source. However, the limitations of the LEDs have previously
prevented the LEDs from completely replacing the existing light
sources of today, such as incandescent light bulbs, halogen spot
lights, and linear fluorescent bulbs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Examples of an LED-based lighting system are illustrated in
the figures. The examples and figures are illustrative rather than
limiting.
[0004] FIG. 1 shows a perspective view illustrating an example
mixing barrel in an LED-based lamp.
[0005] FIG. 2A shows a perspective view of an example section of
the mixing barrel. FIG. 2B shows a superposition of the shape of
the lower edge and the upper edge of an example mixing barrel
section
[0006] FIG. 3 shows a top view of example mixing barrel sections
clamped together.
[0007] FIG. 4 shows a perspective view illustrating an example
mixing barrel covered by a diffuser plate.
[0008] FIG. 5 shows a cross-section of an example LED-based
lighting system that includes a mixing barrel.
[0009] FIG. 6 is a flow diagram illustrating an example process of
mixing light from an LED array using a mixing barrel.
[0010] FIG. 7 shows a perspective view illustrating a sample
apparatus including a high density LED array.
[0011] FIG. 8 shows a cross sectional view of one LED within the
array and components beneath the LED.
[0012] FIG. 9A illustrates a top view of a point light source.
[0013] FIG. 9B illustrates an example cross-section of the point
light source along the line A-A''.
[0014] FIG. 10A illustrates a top view of a point light source in
another embodiment.
[0015] FIG. 10B illustrates an example cross-section of the point
light source along the line B-B''.
[0016] FIG. 10C illustrates an example cross-section of the
collimated light source along the line C-C''.
[0017] FIG. 10D illustrates an example cross-section of the
collimated light source along the line B-B'' with optional
components.
[0018] FIG. 11A illustrates an example cross-section of a
collimated point source.
[0019] FIG. 11B illustrates another example cross-section of a
collimated point source.
[0020] FIG. 11C illustrates a bottom view of a collimator.
[0021] FIG. 11D illustrates a cross-section of the collimator along
the curve line A-A in FIG. 11C.
[0022] FIG. 11E illustrates an example cross-section of the
collimated point source with a support structure.
[0023] FIG. 11F illustrates light rays exiting the collimated point
source.
[0024] FIG. 11G illustrates a cross-sectional view of the
collimated point source with optional exit interfaces.
[0025] FIG. 12A illustrates an example of a perspective view of a
linear light source.
[0026] FIG. 12B illustrates an example cross-section of the linear
light source along line D-D''.
[0027] FIG. 12C illustrates an example cross-section of the linear
light source along line E-E''.
[0028] FIG. 12D illustrates an example cross-section of the linear
light source with an optional tapered end.
[0029] FIG. 13A illustrates a cross-sectional view of a remote
phosphor light source.
[0030] FIG. 13B illustrates light ray patterns within the remote
phosphor light source.
[0031] FIG. 14A illustrates a cross-sectional view of a remote
phosphor light source.
[0032] FIG. 14B illustrates a phosphor array arrangement for the
remote phosphor light source.
[0033] FIG. 15 illustrates an example cross-section of a dual-end
linear light source.
[0034] FIG. 16A illustrates an example cross-section of a serial
linear light source.
[0035] FIG. 16B illustrates how the serial linear light sources can
be serially lined up.
[0036] FIG. 17B illustrates a ray tracing light rays exiting a
throat region of FIG. 17A.
[0037] FIG. 18A illustrates a cross-sectional view of a flat
collimated light source.
[0038] FIG. 18B illustrates a perspective view of flat panels
utilizing an array of flat collimated light sources.
[0039] FIG. 19A illustrates a cross-sectional view of a remote
phosphor light source.
[0040] FIG. 19B is a ray tracing of the light back scattering from
a first phosphor module to a second phosphor module via a short
pass filter.
[0041] FIG. 19C illustrates a manufacturing process of embedding a
hemispherical short pass filter.
[0042] FIG. 19D illustrates a cross-sectional view of the remote
phosphor light source with heat dissipation elements.
[0043] FIG. 20 illustrates a cross-section of an example
configuration of a phosphor array and LED array in a remote
phosphor light source
[0044] FIG. 21A illustrates a cross-section of an example
configuration of a phosphor array in a remote phosphor light
source
[0045] FIG. 21B illustrates a ray tracing of light emission from a
phosphor array.
DETAILED DESCRIPTION
[0046] A mixing barrel apparatus is described for mixing light from
an array of LEDs that emit light having different colors. Although
the array can be quite large, the mixing barrel funnels the light
from the array and re-emits the light from a smaller area, thus
resulting in a narrow beam pattern being emitted from the lamp that
houses the LED array. Additionally, as the light reflects multiple
times from the inner surface of the mixing barrel, the light from
the different color LEDs are mixed. In one embodiment, the mixing
barrel has an air cavity. In another embodiment, the mixing barrel
contains a transparent refractive block that causes at least a
portion of the light emitted by the LED array to be totally
internally reflected within the refractive block to minimize loss
of light occurring upon reflection from the mixing barrel
surface.
[0047] Various aspects and examples of the invention will now be
described. The following description provides specific details for
a thorough understanding and enabling description of these
examples. One skilled in the art will understand, however, that the
invention may be practiced without many of these details.
Additionally, some well-known structures or functions may not be
shown or described in detail, so as to avdid unnecessarily
obscuring the relevant description.
[0048] The terminology used in the description presented below is
intended to be interpreted in its broadest reasonable manner, even
though it is being used in conjunction with a detailed description
of certain specific examples of the technology. Certain terms may
even be emphasized below; however, any terminology intended to be
interpreted in any restricted manner will be overtly and
specifically defined as such in this Detailed Description
section.
[0049] A light emitting diode (LED) emits light in a narrow band of
wavelengths. Two or more LEDs emitting in different wavelength
bands can be used together in a lamp to generate composite light
having a desired color temperature. When light from multiple LEDs
are used together, the light from the LEDs should be mixed so that
the light appears uniform, rather than as localized spots of
different color light. Additionally, when multiple LEDs are used in
an LED array, the array has a large area and does not provide a
narrow output beam angle. Described below is a mixing barrel that
can be used to homogenize the light emitted from an LED array and
to effectively provide a small source with a narrow output beam
angle.
Mixing Barrel with Air Cavity
[0050] FIG. 1 shows a perspective view illustrating an example
mixing barrel in an LED-based lamp. The LED-based lamp includes an
LED array 110 that has multiple LEDs, and the LEDs emit light at
two or more different wavelength bands.
[0051] In one embodiment, the mixing barrel has two sections 112,
114 that are clamped together by holders 121, 122. In one
embodiment, the holders 121, 122 suspend the mixing barrel sections
112, 114 slightly above the LED array 110 so that there is a
clearance space between the mixing barrel and the LED array 110 to
prevent pressure from being placed on the array.
[0052] In one embodiment, each of the sections 112, 114 of the
mixing barrel is made from formable sheet metal, such as aluminum.
The lower edge of the sheet metal sections that is closest to the
LED array is crimped to form a shape that conforms, or nearly
conforms, to the shape of the LEDs in the array, while the upper
edge of the sheet metal sections farthest from the array is smooth.
Note that while the terms `lower edge` and `upper edge` are used to
describe the mixing barrel, the mixing barrel can be oriented in
any direction. Because the lower edge of the barrel is crimped to
follow the small features that correspond to the shape of the LEDs,
the metal of the mixing barrel should be fairly thin. By shaping
the lower edge of the mixing barrel to match the shape of the LEDs,
the amount of light emitted by the LEDs that is captured by the
mixing barrel can be maximized. Additionally, the total length of
the crimped lower edge and the smooth upper edge are substantially
equal for ease of manufacturing the mixing barrel.
[0053] Once captured, the light from the LEDs reflects multiple
times against the inner surface of the mixing barrel as it is
funneled towards the upper edge of the mixing barrel. In one
embodiment, the inner surface of the mixing barrel is coated with a
highly reflective specular coating, such as a silver coating. By
using a highly reflective specular coating, the energy lost each
time light from the LEDs reflects from the surface of the mixing
barrel is minimized. Further, a transparent coating, such as
silicon dioxide, can be placed over the specular coating as a
protective layer.
[0054] In one embodiment, instead of coating the inner surface of
the mixing barrel with a highly reflective coating, a highly
reflective diffusive substrate can be used, such as White97 film or
DuPont.TM. DLR80 from WhiteOptics of Newark, Del. or a
Teflon.TM.-based solid, such as Gore DRP from W. L. Gore &
Associates, Inc. of Newark, Del. By using a highly reflective
diffuse material, light impinging on the surface is reflected at
multiple angles, resulting in further mixing of the different
colors of light from the LEDs.
[0055] In another embodiment, the mixing barrel can be formed using
a plastic injection-molded mixing barrel that is electroless nickel
plated to form a metallic base coat. The base coat is then coated
with a highly reflective specular coating, such as silver or
aluminum, and optionally coated with a high reflectivity dielectric
stack coating.
[0056] In yet another embodiment, the mixing barrel can be made
from press-molded glass that is coated with a highly reflective
specular coating.
[0057] With either the press-molded glass or plastic
injection-molded mixing barrel, the diffusive reflective materials
specified above can be conformally applied to the surface of mixing
barrel. Alternatively, there are diffuse white reflector coatings
that can be applied to the mixing barrel surface that have nearly
the same performance but are more delicate. For example, barium
sulfate (BaSO.sub.4) can be applied as a powder-spray to the
surface by using a carrier solution such as polyvinyl alcohol
(PVA). High reflectivity white diffuse paints can also be used that
typically contain a high percentage of BaSO.sub.4.
[0058] FIG. 2A shows a perspective view of an example section of
the mixing barrel. The crimped lower edge 205 is gradually smoothed
into, in this example, a half circle at the upper edge 206. FIG. 2B
shows a superposition of the shape of the lower edge 250 and the
shape of the upper edge 251 of an example mixing barrel
section.
[0059] Additionally, in this example, the mixing barrel section has
two flat portions 210, 211 at the ends. These flat portions 210,
211 are clamped to the corresponding flat portions on the opposing
mixing barrel section to form the reflective cavity of the mixing
barrel.
[0060] FIG. 3 shows a top view of example mixing barrel sections
310, 311 clamped together. The holder clamping the mixing barrel
sections together is shown to be transparent in this figure to show
the relative positioning of the LED array 320 and the mixing barrel
sections 310, 311.
[0061] FIG. 4 shows a perspective view of example mixing barrel
sections 410, 411 with a diffuser 420 seated on the upper edge of
the sections 410, 411. The diffuser serves to further mix the light
from the different color LEDs exiting beyond the upper edge of the
mixing barrel to smooth out any hot spots from the individual LEDs
in the LED array. The diffuser can be made from plastic or
glass.
[0062] FIG. 5 shows a cross-section of an example LED-based
lighting system that includes the mixing barrel 510. In one
embodiment, the mixing barrel 510 is seated on a supporting plate
530 so that the mixing barrel does not contact the LED array 515.
The small gap 540 between the LED array and the mixing barrel 510
is in a low loss region where the amount of direct light flux from
the LEDs is very low and the scatter flux density of light from
within the mixing barrel is also low. Further, FIG. 5 shows the
diffuser plate 520 seated on the top edge of the mixing barrel
510.
Mixing Barrel with Refractive Block
[0063] Despite the use of highly reflective coatings on the inner
surface of the mixing barrel, each time light reflects from the
inner surface of the mixing barrel, some energy is lost since even
the best reflective coatings are lossy. One way to minimize the
number of reflections against the wall of the mixing barrel while
still sufficiently mixing the light from the LEDs is to use a total
internal reflection (TIR) mechanism within the mixing barrel. In
one embodiment, a block of refractive material is used to replace a
portion of the air cavity within the mixing barrel. Because the
light from the LED array that impinges on the mixing barrel can
have a large range of incidence angles, it is difficult to design a
shape for the refractive material that causes all the light from
the LED array to be totally internally reflected. However, the
shape of the refractive block is designed with the result that at
least some of the light from the LEDs undergoes total internal
reflection within the refractive block.
[0064] While the refractive block is placed within the mixing
barrel, there should be a narrow air gap between the refractive
block and the inner wall of the mixing barrel to ensure that the
TIR mechanism works. Any contact between the refractive block and
the mixing barrel wall causes light to leak out to the mixing
barrel wall and reflect off of the wall with the accompanying
energy loss.
[0065] Similarly, if there is contact between the refractive block
and the mixing barrel, light reflected onto the points of contact
can leak out. However, in some embodiments, it may be advantageous
to optically couple the refractive block to the LED array by
placing an optical silicone gel between the refractive block and
the optical silicone gel dome that is already present on
high-volume single LED packages. Then the additional optical
silicone gel acts as an index matching material to minimize the
loss of light entering the mixing barrel.
[0066] In one embodiment, a diffuser plate is bonded to the top of
the refractive block, and the diffuser plate is seated on top of
the mixing barrel's upper edge. This arrangement suspends the
refractive block above the LED array below the mixing barrel, thus
preventing the refractive block from making contact with the LED
array.
[0067] The diffuser plate can also serve as a registration
mechanism to center the refractive block within the mixing barrel
so that there is an air gap between the mixing barrel reflective
wall and the refractive block on all sides.
[0068] Another advantage to using the refractive block is that it
acts as a heat sink for the diffuser plate. In the configuration
for the mixing barrel that has an unfilled air cavity, the diffuser
plate itself is very thin and thus, has a very small heat capacity.
Further, it is surrounded above and below by air that acts as an
insulator. If the surface of the diffuser has an impurity, for
example, flecks of dust, the impurity will absorb the energy of the
light and produce carbonization on the diffuser material causing
further energy absorption and eventually burning up the diffuser.
However, if the diffuser material is laminated to the refractive
block, the block acts as a heat sink for any heat energy absorbed
by the diffuser, thus mitigating heat build up at the diffuser.
[0069] FIG. 6 is a flow diagram illustrating an example process of
mixing light from an LED array using a mixing barrel. At block 605,
the system emits light from an array of LEDs, and the LEDs emit
light at different wavelength bands.
[0070] Then at block 610, the light emitted from the LED array is
captured by the mixing barrel. If the mixing barrel has an air
cavity, the captured light is mixed as a result of multiple
reflections of the light from the inner reflective surface of the
mixing barrel. If the mixing barrel has a refractive block, that
light is either totally internally reflected within the block or
exits the block to be reflected by the inner reflective surface of
the mixing barrel and re-enters the refractive block. The light
continues to be either totally internally reflected or reflected by
the mixing barrel surface until at block 615, the funnel shape of
the mixing barrel causes the light to be emitted from the top of
the mixing barrel with a narrow beam angle. In one embodiment, the
top of the mixing barrel is covered with a diffuser to further
diffuse the light emitted from the mixing barrel.
[0071] The light emitted from the mixing barrel, with or without
the diffuser, is nearly Lambertian. However, because the exit
window of the mixing barrel is relatively small, it acts as a
smaller source having a lower etendue than the LED array would have
alone. As a result, secondary optics used in conjunction with the
mixing barrel can generate narrower beam angles than the LED array
alone.
[0072] High Density LED Array
[0073] A lighting apparatus having a high density LED array using
high volume, low cost, reliable LEDs is described. The apparatus
may utilize the mixing barrel discussed in previous sections of the
disclosure. FIG. 7 illustrates a sample apparatus including a high
density LED array. The apparatus 700 includes a planar array 710 of
LEDs 712. In one embodiment, the LEDs 712 are high-power LED
packages such as Lumiled Luxeon Rebel or CREE XRG. These LED
packages are highly-tested, high-volume, proven LED packages. The
LEDs 712 are mechanically mounted on top of a heat conductor 720.
For each of LEDs 712, there is a thermal pad 730 between the LED
and the heat conductor 720. The thermal pad may contain copper. In
one embodiment, there is an individual thermal pad beneath each
LED. In another embodiment, one or more LEDs may share one thermal
pad. The LED is thermally coupled to the thermal pad 730 and then
the thermal pad 730 is thermally coupled to the heat conductor 720.
In one embodiment, the LED is thermally coupled by means of solder
or oriented carbon fiber film. The heat conductor may be a
coin-shaped article made of copper. Thus, most heat generated by
the LEDs 712 is transferred to the heat conductor 720 with very
little heat resistance. The heat conductor may connect to another
heat sink to further dissipate the heat. A flexible printed circuit
740 is designed to electrically connect to all the LEDs 712 of the
array 710 via their electrical contacts. A flexible printed circuit
is a patterned arrangement of printed wiring utilizing flexible
base material with or without flexible cover layers. The flexible
printed circuit uses flexible base material so that mechanical
stress due to the thermal expansion and contraction is minimized
and cracking is prevented. The apparatus has superior thermal
dissipation ability because the heat generated by the LEDs 712
flows through a thermal channel of the thermal pad 730 and the heat
conductor 720 with minimum thermal resistance. Therefore, it is
possible to arrange the LEDs 712 in close proximity while not
overheating the LEDs. The LEDs 712 may be arranged with an average
spacing between the neighboring LEDs of less than 4 millimeters,
preferably less than 3 millimeters. As shown in FIG. 7, the LED
array 710 forms a planar Lambertian disc with a diameter of from
about 10 millimeters to about 18 millimeters. The light intensity
from the planar Lambertian disc to an observer is the same
regardless of the observer's angle of view. The design is a
lighting solution with low cost, high efficacy and reliability. The
product life may exceed 50,000 hours.
[0074] FIG. 8 shows a cross sectional view of one LED within the
array and the components beneath the LED. The LED 812 is mounted on
a heat conductor 820 via a thermal pad 830. The LED 812 may be an
LED package including a ceramic base. The thermal couplings between
the LED 812 and thermal pad 830, and between the thermal pad 830
and heat conductor 820, have minimum thermal resistance. A major
portion of the heat generated by the LED 812 is transferred to the
heat conductor 820 through the highly efficient thermal channel. In
one embodiment, all LEDs within the LED array are mounted on the
same heat conductor via thermal pads. The heat conductor may be
mounted on another heat sink to further dissipate the heat. In one
embodiment, the heat sink may be mounted to the heat conductor by a
screw on the bottom. In another embodiment, the heat sink may be
mounted by screwing the heat sink onto two ears of the heat
conductor. In yet another embodiment, the heat sink may be mounted
by spring steel clips that are analogous to heat sink block clips
for computer CPU chips. The heat sink applies constant spring
pressure between the heat conductor and head sink independent of
time, temperature and cycling. The LED 812 has one or more
electrical contacts 816. In one embodiment, the electric contacts
816 are wire bonds contacts. In another embodiment, the electric
contacts 816 are polyamide holt-melt matrix film (Nickel fiber)
that can be applied by pressure and heat. The film forms an
electrical contact between the LED and contacts pads of a flex
printed circuit. The flexible printed circuit 840 is electrically
connected to the electrical contacts 816 to supply and fine-tune
electric power for the LED 812. Light characteristics such as color
rendering index (CRI) and correlated color temperature (CCT) can be
adjusted by tuning the intensities of the LEDs within the array.
The flexible base material in the flexible printed circuit 840
prevents cracking of ceramic bases of the LED packages due to the
thermal expansion and contraction. As shown in FIG. 8, there is
spacing 870 between the LED 812 and the heat conductor 820. In one
embodiment, epoxy resin can be capillary backfilled in the spacing
870. As a result, the LED electrical contacts 816 is further
isolated for high-voltage tracking with the thermal pad 830. The
epoxy resin may be precision backfilled by a jetting applier or a
drop applier.
[0075] The LED array may contain LEDs with different emitting
colors to achieve better color characteristics and enable color
and/or CCT tuning. In one embodiment, the LED array includes one or
more red-emitting LEDs, one or more blue-emitting LEDs, and one or
more yellow-emitting LEDs. The yellow-emitting LED may have a blue
LED die and a YAG:Ce phosphor, similar to what constructs a
white-emitting LED, but with more YAG:Ce phosphor. In one
embodiment, the extra YAG:Ce phosphor may be applied in a remote
phosphor dome disposed over the existing white-emitting LED to form
a yellow-emitting LED. The remote phosphor dome may be a
hemispherical cap disposed over the LED encapsulation. In another
embodiment, the extra YAG:Ce phosphor may be disposed directly
within the LED packages.
[0076] In another embodiment, the LED array includes one or more
red-emitting LEDs, one or more blue-emitting LEDs, one or more
yellow-emitting LEDs, and one or more cyan-emitting LEDs. The
cyan-emitting LED may have a blue LED die and a Ba:Si Oxynitride
Eu-doped phosphor. In one embodiment, the Ba:Si Oxynitride Eu-doped
phosphor may also be disposed via a remote phosphor dome as
discussed in the previous paragraph. In another embodiment, the
Ba:Si Oxynitride Eu-doped phosphor may be disposed directly within
the LED packages. The LED array with mixing color LEDs may achieve
a wide range of correlated color temperatures (CCTs), such as from
1800 to 7000 Kelvin, while maintaining a high color rendering index
(CRI) of more than 90, or even 95. The solution enables color
tuning by changing the numbers of different color LEDs.
Furthermore, the solution eliminates the need of white LED binning,
since the color shifting is compensated by the mixing of the
different color LEDs. By controlling the throttling of different
color LEDs, a high CRI spectrum is rebuilt by utilizing high
production volume, low cost, reliable LEDs.
[0077] FIG. 9A illustrates a top view of a point light source 900.
The point light source 900 can emulate an incandescent lamp with a
broad beam angle that is color tunable. The point light source 900
is a portable lighting unit that can be plugged into a lamp device.
The point light source 900 can derive electric power in the form of
driving current signals from the lamp device. The point light
source 900 provides light substantially as a single point of light.
The point light source 900 includes a light source window 902. The
light source window 902 can be a diffuser window. The light source
window 902 is shown to be circular. However, it is understood that
the light source window 902 can also be rectangular, elliptical, or
any other shapes.
[0078] FIG. 9B illustrates an example cross-section of the point
light source 900 along the line A-A'' of FIG. 9A. The point light
source 900 includes a substrate 904. The substrate 904 is a solid
layer of material, such as a circuit board, for hosting an
electronic circuitry 908. The point light source 900 includes an
LED array 906 attached to the substrate 904 and electrically
connected to the electronic circuitry 908 on the substrate 904. The
electronic circuitry can be coupled to a power and signal interface
with a lamp device when the point light source 900 is plugged into
the lamp device. The LED array 906, such as the LED array 110 of
FIG. 1, emits light at two or more different wavelength bands.
Optionally, the electronic circuitry 908 can include a memory unit
for storing a color model of the LED array 906. The color model can
define the driving signal necessary to produce different color
spectra at different temperatures and power supply settings. Also
optionally, the electronic circuitry 908 can be coupled to a sensor
unit within the point light source 900 for detecting the color
spectrum produced by the LED array 906 within the point light
source 900. For example, the sensor unit can be attached to the
substrate 904 adjacent to the LED array 906. The electronic
circuitry 908 and the side of the substrate 904 facing the LED
array 906 can be optionally coated with a reflective coating. For
example, the substrate 904 can be an AIN (Aluminum Nitride) board
with silver and SiO2 protective overcoat over the substrate 904
except where the electrical contact pads are underneath the LED
array 906.
[0079] The LED array 906 can, for example, be organized in a
circular fashion. The LED array 906 can be organized to minimize
the distance between the LEDs for both spaces saving and better
mixing of the colors. A mixer wall 914 can be placed around the LED
array 906. The mixer wall 914, for example, can be the mixing
barrel sections 112 and 114 of FIG. 1, the mixing barrel sections
of FIG. 2A and FIG. 2B, the mixing barrel section 310 and 311 of
FIG. 3, the mixing barrel sections 410 and 411 of FIG. 4, or the
mixing barrel 510 of FIG. 5. The mixer wall 914 can include an
aperture that is conformal around the LED array 906. The internal
linings of the mixer wall 914 facing the LED array 906 can be
reflective. For example, the internal side of the mixer wall 914
can include a reflective coating 916, such as a silver coat. The
reflective coating 916 can reflect a large percentage light rays,
such as 98% reflectivity or above.
[0080] FIG. 10A illustrates a top view of a point light source 1000
in another embodiment. The top view of the point light source 1000
illustrates a mixer wall 1012 around a diffuser window 1014 that
emits color tunable diffused lighting with a broad beam spread.
[0081] FIG. 10B illustrates an example cross-section of the point
light source 1000 along line B-B'' of FIG. 10A. The point light
source 1000 can emulate a spot light lamp with a narrow beam spread
from an LED array 1002 that is color tunable. The point light
source 1000 includes the LED array 1002 coupled to an electronic
circuitry 1004 on a substrate 1006. The LED array 1002 can be the
LED array 906 of FIG. 9B. The electronic circuitry 1004 and the
substrate 1006 can respectively be the electronic circuitry 908 and
the substrate 904 of FIG. 9B. The point light source 1000 includes
a light mixing pipe 1008 over the LED array 1002. The light mixing
pipe 1008 can be the refractive block described above. The light
mixing pipe 1008 can be in direct contact with the LED array 1002.
The light mixing pipe 1008 is a solid light piping media that
allows for total internal reflection (TIR) for light rays emitted
from the LED array 1002. The light mixing pipe 1008 can be
surrounded by an air gap 1010 apart from the mixer wall 1012. The
mixer wall 1012 can be the mixer wall 914 of FIG. 9B.
[0082] Optionally, the diffuser window 1014 can be coupled to the
light mixing pipe 1008 on the opposite end of the light mixing pipe
1008 away from the LED array 1002. The diffuser window 1014 can be
optically bonded to the light mixing pipe 1008 as shown in FIG.
10B. Alternatively, the diffuser window 1014 can be separated from
the light mixing pipe 1008 with an air gap similar to the light
source window 902 of FIG. 9B and attached to the light source 1000,
such as by a clipping mechanism. In one example, the diffuser
window is integral to the top surface of the light mixing pipe
1008. A photoresist patterned with a laser can be placed on the top
surface. The pattern can be selected for optical light diffusion
properties. The top surface can then be coated with an electroless
nickel that develops into a shin that serves as the diffuser window
1014.
[0083] The light mixing pipe 1008 can substantially provide TIR
when light rays intersect with the external walls of the light
mixing pipe 1008 at a TIR angle. However, some back scattering from
the diffuser window 1014 may cost a small portion of light rays to
exit out of the light mixing pipe 1008. In those cases, the mixer
wall 1012 provides a reflective coating 1016, similar to the
reflective coating 916, to reflect the escaped light rays back into
the light mixing pipe 1008.
[0084] The point light source 1000 can trade off beam spread with
aperture size. The point light source 1000 can achieve a wider beam
spread by having a smaller exit aperture size. Alternatively, the
point light source 1000 can achieve a narrow beam spread by having
a larger aperture size. The exiting window aperture size can be
changed based on the size of the diffuser window 1014 and the mixer
wall 1012. The mixer wall 1012 can be structured as an inverted
column that funnels down the light generated from the LED array
1002 into a smaller exit aperture to produce a point light source
with a broad beam spread.
[0085] FIG. 10C illustrates an example cross-section of the point
light source 1000 along the line C-C'' of FIG. 10B. The
cross-section illustrates the mixer wall 1012 surrounding the light
mixing pipe 1008. The light mixing pipe 1008, while straight along
a vertical axis from the LED array 1002 to the diffuser window
1014, is patterned with non-straight edge(s) perpendicular to the
vertical axis. For example, the light mixing pipe 1008 can have a
straight vertical edge or vertical edges, but is patterned with
curved ripples perpendicular to the vertical axis. This setup
ensures mixing of the light rays as the light traverses upward
through the light mixing pipe 1008 while preventing back scattering
that interfere with the total internal reflection through the light
mixing pipe 1008. The patterning on the light mixing pipe 1008 can
encourage mixing such that there are no dominant wave fronts and
such that the source patterning of the LED array 1002 is
reduced.
[0086] FIG. 10D illustrates an example cross-section of the light
source 1000 along the line B-B'' with optional components. The
light source 1000 includes optionally a silicon gel 1018 to improve
optical coupling with the light mixing pipe 1008. As illustrated,
the silicon gel 1018 is placed over the LED array 1002. The light
mixing pipe 1008 can be made of glass acrylic the on a silicone or
glass with silicone overmolded. The light mixing pipe 1008 may
include a parabolic collimating region 1020 around the LED array
1002. The mixer wall 1012 may be tuned for exit being distribution,
such as the circumferential waviness similar to the profile of the
light mixing pipe 1008 in FIG. 10C. The diffuser 1014 may be
textured or smooth. The diffuser 1014 may be based on depositing of
cloudy resin, an optical silicone, or a texturing of the light
mixing pipe 1008.
[0087] FIG. 11A illustrates an example cross-section of a
collimated point source 1100A. The collimated point source 1100A
can be a modification of the point light source 900 or the point
light source 1000. The top view of the collimated point source
1100A is similar to FIG. 9A or FIG. 10A. The example cross-section
is taken as a vertical cross-section through the top of the
collimated point source 1100A in the same manner as illustrated by
the cross-sections of FIG. 9B and FIG. 10B.
[0088] The collimated point source 1100A includes an LED array 1102
on a substrate 1104. The LED array 1102 can be similar to the LED
array 906 or the LED array 1002. The substrate 1104 (electronic
circuitry not shown for illustrative purposes) can be similar to
the substrate 904 or the substrate 1006. Conformal around the LED
array 1102 is a low angle reflective wall 1106. A mixer wall 1108
can surround the LED array 1102 extending away from the LED array
1102 and the substrate 1104 in an expanding cone shape. Coupled to
the LED array 1102 is a light mixing pipe 1110. The light mixing
pipe 1110 can be similar to the light mixing pipe 1008 of FIG. 10B.
The light mixing pipe 1110 allows substantial total internal
reflection when light rays intersect an external surface of the
light mixing pipe 1110 below a maximum angle from the external
surface. The low angle reflective wall 1106 ensures that any
escaped light rays returns to the light mixing pipe 1110 below the
maximum angle to ensure TIR. The cross-section of the light mixing
pipe 1110 can be rippled patterned in the same manner as the light
mixing pipe 1008 is illustrated in FIG. 10 C Sitting on top of the
light mixing pipe 1110 is a collimator 1112A. The mixer wall 1108
can provide support for the collimating exist surface 1112A. The
collimator 1112A folds angled light rays traveling up the light
mixing pipe 1110 to become collimated as it exits away from the
collimator 1112A. In some embodiments, a diffuser window 1114 can
be placed over the collimator 1112A. The diffuser window 1114 can
be optically bonded to the collimator 1112A or be attached to the
collimator 1112A with an air gap therebetween. The collimator 1112A
can be support Fresnel optics over the collimator 1112A. The
selection of the collimator 1112A determines the beam angle. Hence,
the collimator 1112A coupled to the light mixing pipe 1110 enables
a light source that can tune its beam angle without having to
change the underlying lamp. It has been discovered that a profile
height 1116 of the collimated light source 1100A can be minimal by
use of the collimator 1112A. A source area 1118 of the LED array
906 is also minimized allowing for optimal mixing of the source
patterns.
[0089] FIG. 11B illustrates another example cross-section of a
collimated point source 1100B. The collimated point source 1100B
includes the LED array 1102. Optionally over the LED array 1102 is
an optical silicone 1103. The light mixing pipe 1110 sits over the
LED array 1102, such as attached to the optical silicone 1103.
Light mixing pipe 1110, optionally, has a collimating region 1111.
The collimating region 1111 is similar to the collimating region
1020 with a parabolic shaped over the LED array 1102 to improve the
efficiency of total internal reflection from the LED array
1102.
[0090] Separated by an air gap from the light mixing pipe 1110 is
the mixer wall 1108 with the reflective inner surface. The mixer
wall 1108 can be sheet metal, glass, plastic, or any other material
with a reflective inner surface. Both the light mixing pipe 1110
and the mixer wall 1108 can optionally maintain a throat region
1120. Light rays exiting the throat region 1120 enters a collimator
1112B. The collimator 1112B can be a retro reflective lens with a
convex vortex groove in the center of a surface facing away from
the light mixing pipe 1110. The collimator 1112B narrows the beam
of light exiting the collimator 1112B by retro-reflective bounces.
The mixer wall 1108 can extend beneath the collimator 1112B to
prevent any back scattering light rays from exiting beneath the
collimator 1112B towards the light mixing pipe 1110. The collimator
1112 B may optionally have reflective coating on the side facing
towards the substrate 1104 to ensure that light rays exit the
collimator 1112B in the intended direction of the collimated light
source 1100.
[0091] FIG. 11C illustrates a bottom view of a collimator 1112C.
The collimator 1112C can be the collimator 1112A or the collimator
1112B. The collimator 1112C has a radially patterned bottom surface
with grooves 1122 each extending from a center of the collimator
1112C outwards. For example the grooves 1122 can be straight
triangular prism ditches. The grooves 1122 may be manufactured by
molding the collimator 1112C or silicone overmolding.
[0092] FIG. 11D illustrates a cross-section of the collimator 1112C
along the curved line A-A. The grooves 1120 can be at substantially
45 degrees angle with respect to a plane of the substrate 1104.
That is the grooves 1120 may have a 90 degrees inner groove
angle.
[0093] FIG. 11E illustrates another example cross-section of the
collimated point source with a support structure 1124. The support
structure 1124 surrounds the mixer wall 1108 and the collimator
1112A, 1112B, or 1112C. The support structure 1124 provides
physical support to the rest of the collimated light source 1100.
The support structure 1124 can protrude slightly above the
collimator 1112A/1112B/1112C. An outer diameter 1126 of the
collimator 1112A/1112B/1112C over a throat diameter 1128 of the
throat region 1120 is ideally equal to or greater than 10.
[0094] FIG. 11F illustrates light rays exiting the collimated point
source 1110. Light rays exiting the collimated point source 1100
has a singular being front with small local angle variation at any
given radial position. Conventional floodlight parabolic reflectors
around a light source to collimate beams create a superposition of
collimated beams from the reflector and angle beams from the light
source. Unlike the conventional floodlight reflectors, the light
rays exiting the collimated point source 1110 has uniform beam
angle for further collimation.
[0095] FIG. 11G illustrates a cross-sectional view of the
collimated point source 1110 with optional exit interfaces. The
optional exit interfaces can be modular attachments to the
collimated point source 1110. For example an optional exit
interface can be the diffuser window 1114. The optional exit
interface can also be a Fresnel plate 1130 is illustrative.
Different Fresnel plate 1130 can create narrower or wider exit
beams. The Fresnel plate 1130 can also create patterns of light
such as asymmetric light, square patterned light, or other
patterned light. The collimator 1112A/1112B/1112C may have an exit
surface that is optionally more did with a moth eye anti-reflective
surface. The moth eye surface can be a pattern of bumps, each
roughly below a micron, such as around 200 nm high and spaced on
300 nm centers. The bumps are smaller than the wavelength of
visible light, so the light sees the surface as having a continuous
refractive index gradient between the air and the medium, which
decreases reflection by effectively removing the air-lens
interface. The bump protrusions with progressive index improve the
efficiency of exiting collimated beams.
[0096] FIG. 12A illustrates an example of a perspective view of a
linear light source 1200A. The linear light source 1200A is a
one-dimensional light source that illuminates along a line. The
linear light source 1200A can be rigid along the line or be
flexible. An electronic circuitry 1202 exists on one end of the
linear light source 1200A. The electronic circuitry 1202 can be
coupled to an LED array (shown in FIG. 12B) to provide power and
signal for driving the LED array. The electronic circuitry 1202 can
be the electronic circuitry 908 or the electronic circuitry 1004 as
illustrated above. Optionally, a substrate can be used to support
the electronic circuitry 1202.
[0097] FIG. 12B illustrates an example cross-section of the linear
light source 1200A along line D-D'' of FIG. 12A. The linear light
source 1200A includes an LED array 1204 on one end of the linear
light source 1200A. The LED array 1204 is coupled to the electronic
circuitry 1202 for providing power and driving signals to color
tune the LED array 1204. A throat region 1206 surrounds the LED
array 1204. The throat region 1206 sets the beam angle of light
rays running down a light mixing pipe 1208. The light mixing pipe
1208 can be made of the same material as the light mixing pipe 1008
or the light mixing pipe 1110 previously described. The light
mixing pipe 1208 includes a plurality of cut outs 1210. The cut
outs 1210 can be air cavities. The cut outs 1210 can be shaped as
triangular wedges. Each of the cut outs 1210 can have a 45 degree
angle interface with the light mixing pipe 1208 with respect to the
pipe axis of the light mixing pipe 1208.
[0098] FIG. 12C illustrates an example cross-section of the linear
light source 1200A along line E-E'' of FIG. 12B. The cross section
illustrates an elliptical shape of the light mixing pipe 1208. In a
preferred embodiment, the elliptical shape is at least two times as
long as it is wide. The interface between each of the cut outs 1210
into the light mixing pipe 1208 acts as a first focal point 1222 of
the elliptical shape. Light rays that scatter off of the cut outs
1210 scatter all around the light mixing pipe 1208 and end up
folding back on a second focal point 1224 of the elliptical shape.
Above and near the second focal point is a reflective wall 1212,
similar to the mixer wall 1012 or the mixer wall 1108, with an exit
aperture 1216. The focused light rays from the second focal point
1224 instead of reflecting back would exit the exit aperture 1216.
The exit aperture 1216 allows light rays having scattered off of
the cut outs 1210 to exit out along a line across from all of the
cut outs 1210. For example, the light mixing pipe 1208 can be 12
millimeters wide. The exit aperture 1216 can be around 2 to 3
millimeters wide along the circumference of the light mixing pipe
1208 and extends lengthwise along the pipe axis of the light mixing
pipe 1208. As a result, the linear light source 1200A provides an
illumination along the exit aperture 1216 that extends along the
length of the linear light source 1200A.
[0099] The illumination along the linear light source 1200A may
have a narrow beam spread. Optionally, special lens 1218 can be
attached over and along the exit aperture 1216 to make the beam
spread more uniform or to change the beam spread. The special lens
1218 can be a linear refractive collimating lens. The special lens
1218 can have a concave side facing the exit aperture 1216 and a
convex side away from the light mixing pipe 1208. The special lens
1218 can be in a wrapping shape around the light mixing pipe 1208
as illustrated. The special lens 1218 can ensure that the beam
angle is wide along the pipe axis of the exit aperture 1216 but
narrow along the circumference of the light mixing pipe 1208 or
vice versa. Alternatively, the special lens 1218 is selected to
provide a uniform illumination at different angles. For example,
the special lens 1218 can fold light rays in a pattern such that
more intensity is going towards higher angles and less intensity is
going towards lower angles so that while having the same beam
spread, the beam is uniform at all angles within the beam spread.
Because without the special lens 1218 light flux would be centered
near the lower angles, the patterning of the special lens 1218 can
generate a uniform distribution of light intensity across different
beam angles.
[0100] To control for even intensity along the pipe axis of the
linear light source 1200A, one or both of the following methods can
be employed. First, the size and/or density of the cut outs 1210
can be manipulated such that a cut out is made at a higher density
from neighboring cut outs when the cut out is farther away from the
LED array 1204. Further, a larger size of a cut out can be used
when the cut out is the farther away from the LED array 1204.
Second, the cross section area (i.e. the ellipse shape of FIG. 12C)
of the light mixing pipe 1208 can be reduced when the cross-section
is farther away from the LED array 1204. This tapering of the light
mixing pipe 1208 maintains the flux density of the light rays along
the pipe axis.
[0101] FIG. 12D illustrates an example cross-section of the linear
your light source with an optional tapered end 1228.
[0102] FIG. 13A illustrates a cross-sectional view of a remote
phosphor light source 1300. The remote phosphor light source 1300
includes a substrate 1302 with electronic circuitry to drive an LED
array 1304 on the substrate 1302. The LED array 1304 can be an LED
array of royal blue LEDs. Over the LED array 1304 is an imaging
pipe. The imaging pipe is a convex lens, such as a double convex
lens. The imaging pipe can be made of solid glass. The imaging pipe
can include a cup shaped pattern for collimating light emitted from
the LED array 1304. The cup shaped pattern can be etched or coated
on the imaging pipe directly. The imaging pipe can have a
reflective surface 1308, such as a silver coating or micro radial
retro-reflective grooves. The reflective surface 1308 has an
opening 1310 across from where the imaging pipe is nearest to or in
contact with the LED array 1304. Within the opening 1310 is a
phosphor array 1312. The phosphor array includes multiple phosphor
modules, such that when light rays from the LED array 1304 hits the
phosphor modules at different colored light is emitted towards a
light mixing pipe 1314. The light mixing pipe 1314 can be part of a
point light source, such as the collimated point source 1100 (as
illustrated) or a point light source 1000.
[0103] FIG. 13B illustrates light ray patterns within the remote
phosphor light source 1300. The LED array 1304 of the remote
phosphor light source 1300 amidst light rays into the imaging pipe.
The light rays from a single LED 1320 converge on a radially
mirrored opposite point across from the imaging pipe. At the
convergence point is where a phosphor module 1322 is located.
[0104] FIG. 14A illustrates a cross-sectional view of a remote
phosphor light source 1400. The remote phosphor light source 1400
includes LED array 1402 on a substrate 1404. On each of the LEDs of
the LED array 1402 can be a limited angle collimating cup 1406. The
first lens 1408 is placed over the LED array 1402 with a spacing
therebetween. The first lens 1408 collimates light emitted from the
LED array 1402. Collimated light rays are then capture by a second
lens 1410. The first lens 1408 and the second lens 1410 are convex
lenses, such as double convex lenses. The second lens 1410 then
focuses the light rays towards a phosphor array 1412. Some amount
of back scattering may occur when the phosphor array 1412 is
excited by the light from the LED array 1402. It has been
discovered that an optional short pass filter 1414 resolve the
problem of back scattering. The short pass filter 1414 allows the
high-frequency short wavelength light from the LED array 1402 to
pass through. The short pass filter 1414, however, reflects the
low-frequency high wavelength light emitted through the excited
phosphor array 1412. When the configuration of the LED array 1402,
the first lens 1408, the second lens 1410, the phosphor array 1412,
and the short pass filter 1414 is symmetric, the reflection of the
short pass filter 1414 places the reflective light rays at a window
radially mirrored from where the LED array 1402 is. FIG. 14B
illustrates a phosphor array arrangement for the remote phosphor
light source. The phosphor array arrangement illustrates that
phosphor modules of the phosphor array 1412 are placed in radially
mirrored pairs of same color such that the short pass filter 1414
reflects light from a phosphor module to another phosphor module of
the some color. The remote phosphor light source 1400 may be
connected to a light source, such as the point light source 900,
the point light source 1000, the collimated light source 1100, or
the linear light source 1200, with the phosphor array 1412 acting
as the LED arrays of the respective light sources.
[0105] FIG. 15 illustrates an example cross-section of a dual-end
linear light source 1500. The dual-end linear light source 1500
includes an LED array 1502 on substrate 1504 with electronic
circuitry to drive the LED array 1502. A collimation chamber 1506
is placed over and around the LED array 1502 on substrate 1504. The
collimation chamber 1506 can be a parabolic wall with a reflective
inner surface. An exit aperture 1508 of the collimation chamber
1506 across from the LED array 1502 its cover by a light mixing
pipe 1510. The light mixing pipe 1510 has a vortex groove 1512 on
the surface away from the collimation chamber 1506. The vortex
groove 1512 in the light mixing pipe 1510 pushes light rays
outwards on two ends. The light mixing pipe 1510 can include
cutouts 1514 similar to the cutouts 1210 of the linear light source
1200.
[0106] FIG. 16A illustrates an example cross-section of a serial
linear light source 1600. The serial linear light source 1600 is a
variant of the linear light source 1200. The serial linear light
source 1600 includes an LED array 1602. Place over the LED array
1602 is a light mixing pipe 1604. The light mixing pipe 1604
includes a first straight section 1606 and a second straight
section 1608 with a bent 1610 therebetween. The light mixing pipe
1604 includes cutouts 1612 similar to the cutouts 1210 of the
linear light source 1200. An optional refractive plate 1614 can be
placed over an exiting aperture 1616 along the second straight
section 1608 of the light mixing pipe 1604 to eliminate axial bias
of light rays exiting the exiting aperture 1616. FIG. 16B
illustrates how the serial linear light sources can be serially
lined up.
[0107] FIG. 17A illustrates a cross-sectional view of a collimated
light source 1700. The collimated tight source 1700 includes a
light emitter array 1702. The light emitter array 1702 can be an
LED array or a phosphor array excited by a LED array, such as by
the remote phosphor, light source 1400. Over the light emitter
array 1702 is a light mixing pipe 1704. The light mixing pipe 1704
can include vertical grooves running along the pipe axes to mix
light. The light mixing pipe 1704 can narrow into a throat region
1706 that widens beam angle of light exiting the light mixing pipe
1704. FIG. 17B illustrates a ray tracing light rays exiting the
throat region 1706 of FIG. 17A. A collimator 1708 is optically
bonded to the light mixing pipe 1704. The collimator 1708 can have
a bottom surface 1709 facing towards the light emitter array 1702
where the bottom surface 1709 has a reflective coating.
Alternatively, the collimator 1708 can have grooves on the bottom
surface 1709 similar to FIG. 11C and FIG. 11D. The bottom surface
1709 can be convex. The bottom surface 1709 can be parabolic.
[0108] The collimator 1708 includes a central convex protrusion
1710 on an opposite of the throat region 1706. Around the central
convex protrusion 1710 is an annular reflective region 1712. The
annular reflective region 1712 can be coated with reflective
material or radially grooved similar to FIG. 11C and FIG. 11D.
Optionally over the collimator 1708 is a cover plate 1720. The
cover plate 1720 can be a Fresnel plate, a diffuser, a lenslet, or
any combination thereof.
[0109] FIG. 18A illustrates a cross-sectional view of a flat
collimated light source 1800. The flat collimated light source 1800
includes an LED array 1802. The light mixing pipe 1804 is attached
over the LED array 1802. The light mixing pipe 1804 can include
vertical grooves parallel to the pipe axes to mix light. Light
mixing pipe 1804 is attached to a cup lens 1806. The cup lens 1806
can be part of the light mixing pipe 1804 or a lens attached to the
light mixing pipe 1804. The cup lens 1806 extends in a convex
fashion from the light mixing pipe 1804 outwards and away. The cup
lens 1806 includes an annular flat portion 1808 with a reflective
coating 1810. Inwards from the annular flat portion 1808 is a
vortex groove 1812 concave into the cup lens 1806. A flat cover
1814 is attached to the annular flat portion 1808. The flat cover
1814 can be made of a clear material, such as glass. A reflector
1816 rests over the flat cover 1814 and the LED array 1802 with the
light mixing pipe 1804 circumferentially surrounded by the
reflector 1816. The reflector 1816 is symmetric. The reflector 1816
can be parabolic, a round bowl shape, or a square bowl shape.
[0110] FIG. 18B illustrates an example perspective view of flat
panels utilizing an array of the flat collimated light source 1800.
The flat panels include a flat panel 1850. The flat-panel 1850 can
be used to simulate sunlight beams, used as surgical spotlight,
used to illuminate playing fields, or high ceiling illumination
applications. A second flat panel 1852 is also illustrated
utilizing an array of the flat collimated light source 1800 with a
square bowl shaped outer shell.
[0111] FIG. 19A illustrates a remote phosphor light source 1900.
The remote phosphor light source 1900 is a variant of the remote
phosphor light source 1300. The remote phosphor light source 1900
includes an LED array 1902 attached on one side of an imaging pipe
1904. The imaging pipe 1904 is a double convex lens. The imaging
pipe 1904 includes small cup shapes around the LED array 1902 with
the bottom of the small cup shapes directly over each LED.
[0112] A hemispherical short pass filter 1906 may be embedded
within the imaging pipe 1904. The imaging pipe 1904 is attached to
a phosphor array 1908 on an opposite side of the imaging pipe 1904
from the LED array 1902. High-frequency light from the LED array
1902 can pass through the short pass filter 1906. However, the
backscatter emitted from a first phosphor module 1910 of the
phosphor array 1908 is reflected by the short pass filter 1906 to a
second phosphor module 1912 at a position radially opposite to the
first phosphor module 1910. FIG. 19B is a ray tracing of the light
back scattering from the first phosphor module 1910 to the second
phosphor module 1912 via the short pass filter 1906.
[0113] FIG. 19C illustrates a manufacturing process of embedding
the hemispherical short pass filter 1906. A hemisphere section 1952
of the imaging pipe 1904 is made. A short pass filter coating 1954
is coated onto the round part of the hemisphere section 1952. A
base portion 1956 of the imaging pipe 1904 is then made. The base
portion 1956 can be made from a mold of the shape of the hemisphere
section around a mold of a double convex lens. Alternatively the
hemisphere section 1952 and the base portion 1956 can be cut from
the same double convex lens. Then the hemisphere section 1952 is
inserted with an optical silicone bond to make the imaging pipe
1904.
[0114] FIG. 19D illustrates a cross-sectional view of the remote
phosphor light source 1900 with heat dissipation elements.
Optionally, the remote phosphor light source 1900 can include a
cold plate 1960 over the imaging pipe 1904. The cold plate 1960 can
surround the phosphor array 1908. Optionally, the remote phosphor
light source 1900 can also include a heat sink 1962 underneath the
LED array 1902. Optionally, the LED array 1902 can be thermally
coupled to the heat sink 1962 via a thermal conducting element.
[0115] FIG. 20 illustrates a cross-section of an example
configuration of a phosphor array 2002 and LED array 2004 in a
remote phosphor light source, such as the remote phosphor light
source 1900, the remote phosphor light source 1300, or the remote
phosphor light source 1400. The phosphor array 2002 is sandwiched
between an imaging pipe 2006 and a light mixing pipe 2008. A flat
surface of the imaging pipe 2006 is on each phosphor module of the
phosphor array 2002. A flat surface of the light mixing pipe 2008
is on each phosphor module of the phosphor array 2002. The flat
surfaces can contact each phosphor module directly or an optical
silicone bonded to each phosphor module. A first collimation well
2010 can form around the light mixing pipe 2008. An imaging well
2012 can form around the imaging pipe 2006. The first collimation
well 2010 and the imaging well 2012 can have a vortex shape with a
low angle of slant with respect to a normal vector from the flat
surfaces. Similarly a flat surface of the imaging pipe 2006 is on
each LED of the LED array 2004. The imaging pipe 2006 can include a
second collimation well 2018 around the flat surface over each LED.
The second collimation well 2018 can also be vortex shaped with the
low angle of slant with respect to a normal vector from the flat
surface over each LED.
[0116] FIG. 21A illustrates a cross-section of an example
configuration of a phosphor array 2102 in a remote phosphor light
source, such as the remote phosphor light source 1900, the remote
phosphor light source 1300, or the remote phosphor light source
1400. The phosphor array 2102 can be hemispherical shaped. An
imaging pipe 2106 can be attached on a concave side of the phosphor
modules of the phosphor array 2102. The imaging pipe 2106 includes
bumps 2108 that fit the concave side of the phosphor modules. A
light mixing pipe 2110 includes cup shaped dents 2112 that fit a
convex side of the phosphor modules. The light mixing pipe 2010 can
optionally have a collimation well 2114. The imaging pipe 2106 has
imaging wells 2116 in between the bumps 2108.
[0117] FIG. 21B illustrates a ray tracing of light emission from
the phosphor array 2102. As illustrated, blue color light rays
intersect phosphor layers of the phosphor array 2102 at a broad
beam spread angle. Light emission from the phosphor array 2102 is
narrowed as compared to the broad beam spread because of the
structures illustrated in the light mixing pipe 2110.
[0118] Unless the context clearly requires otherwise, throughout
the description and the claims, the words "comprise," "comprising,"
and the like are to be construed in an inclusive sense (i.e., to
say, in the sense of "including, but not limited to"), as opposed
to an exclusive or exhaustive sense. As used herein, the terms
"connected," "coupled," or any variant thereof means any connection
or coupling, either direct or indirect, between two or more
elements. Such a coupling or connection between the elements can be
physical, logical, or a combination thereof. Additionally, the
words "herein," "above," "below," and words of similar import, when
used in this application, refer to this application as a whole and
not to any particular portions of this application. Where the
context permits, words in the above Detailed Description using the
singular or plural number may also include the plural or singular
number respectively. The word "or," in reference to a list of two
or more items, covers all of the following interpretations of the
word: any of the items in the list, all of the items in the list,
and any combination of the items in the list.
[0119] The above Detailed Description of examples of the invention
is not intended to be exhaustive or to limit the invention to the
precise form disclosed above. While specific examples for the
invention are described above for illustrative purposes, various
equivalent modifications are possible within the scope of the
invention, as those skilled in the relevant art will recognize.
While processes or blocks are presented in a given order in this
application, alternative implementations may perform routines
having steps performed in a different order, or employ systems
having blocks in a different order. Some processes or blocks may be
deleted, moved, added, subdivided, combined, and/or modified to
provide alternative or subcombinations. Also, while processes or
blocks are at times shown as being performed in series, these
processes or blocks may instead be performed or implemented in
parallel, or may be performed at different times. Further any
specific numbers noted herein are only examples. It is understood
that alternative implementations may employ differing values or
ranges.
[0120] The various illustrations and teachings provided herein can
also be applied to systems other than the system described above.
The elements and acts of the various examples described above can
be combined to provide further implementations of the
invention.
[0121] Any patents and applications and other references noted
above, including any that may be listed in accompanying filing
papers, are incorporated herein by reference. Aspects of the
invention can be modified, if necessary, to employ the systems,
functions, and concepts included in such references to provide
further implementations of the invention.
[0122] These and other changes can be made to the invention in
light of the above Detailed Description. While the above
description describes certain examples of the invention, and
describes the best mode contemplated, no matter how detailed the
above appears in text, the invention can be practiced in many ways.
Details of the system may vary considerably in its specific
implementation, while still being encompassed by the invention
disclosed herein. As noted above, particular terminology used when
describing certain features or aspects of the invention should not
be taken to imply that the terminology is being redefined herein to
be restricted to any specific characteristics, features, or aspects
of the invention with which that terminology is associated. In
general, the terms used in the following claims should not be
construed to limit the invention to the specific examples disclosed
in the specification, unless the above Detailed Description section
explicitly defines such terms. Accordingly, the actual scope of the
invention encompasses not only the disclosed examples, but also all
equivalent ways of practicing or implementing the invention under
the claims.
[0123] While certain aspects of the invention are presented below
in certain claim forms, the applicant contemplates the various
aspects of the invention in any number of claim forms. For example,
while only one aspect of the invention is recited as a
means-plus-function claim under 35 U.S.C. .sctn.112, sixth
paragraph, other aspects may likewise be embodied as a
means-plus-function claim, or in other forms; such as being
embodied in a computer-readable medium. (Any claims intended to be
treated under 35 U.S.C. .sctn.112, 116 will begin with the words
"means for.") Accordingly, the applicant reserves the right to add
additional claims after filing the application to pursue such
additional claim forms for other aspects of the invention.
* * * * *