U.S. patent application number 15/261351 was filed with the patent office on 2016-12-29 for system and method for providing color light sources in proximity to predetermined wavelength conversion structures.
The applicant listed for this patent is SORAA, INC.. Invention is credited to ARPAN CHAKRABORTY, WILLIAM D. HOUCK, MICHAEL R. KRAMES, FRANK M. STERANKA, TROY TROTTIER.
Application Number | 20160377262 15/261351 |
Document ID | / |
Family ID | 50781161 |
Filed Date | 2016-12-29 |
![](/patent/app/20160377262/US20160377262A1-20161229-D00000.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00001.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00002.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00003.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00004.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00005.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00006.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00007.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00008.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00009.png)
![](/patent/app/20160377262/US20160377262A1-20161229-D00010.png)
View All Diagrams
United States Patent
Application |
20160377262 |
Kind Code |
A1 |
KRAMES; MICHAEL R. ; et
al. |
December 29, 2016 |
SYSTEM AND METHOD FOR PROVIDING COLOR LIGHT SOURCES IN PROXIMITY TO
PREDETERMINED WAVELENGTH CONVERSION STRUCTURES
Abstract
An optical device includes a light source with at least two
radiation sources, and at least two layers of wavelength-modifying
materials excited by the radiation sources that emit radiation in
at least two predetermined wavelengths. Embodiments include a first
plurality of n radiation sources configured to emit radiation at a
first wavelength. The first plurality of radiation sources are in
proximity to a second plurality of m of radiation sources
configured to emit radiation at a second wavelength, the second
wavelength being shorter than the first wavelength. The ratio
between m and n is predetermined. The disclosed optical device also
comprises at least two wavelength converting layers such that a
first wavelength converting layer is configured to absorb a portion
of radiation emitted by the second radiation sources, and a second
wavelength converting layer configured to absorb a portion of
radiation emitted by the second radiation sources.
Inventors: |
KRAMES; MICHAEL R.;
(MOUNTAIN VIEW, CA) ; TROTTIER; TROY; (SAN JOSE,
CA) ; STERANKA; FRANK M.; (SAN JOSE, CA) ;
HOUCK; WILLIAM D.; (FREMONT, CA) ; CHAKRABORTY;
ARPAN; (CHANDLER, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SORAA, INC. |
Fremont |
CA |
US |
|
|
Family ID: |
50781161 |
Appl. No.: |
15/261351 |
Filed: |
September 9, 2016 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14531545 |
Nov 3, 2014 |
|
|
|
15261351 |
|
|
|
|
14256670 |
Apr 18, 2014 |
8905588 |
|
|
14531545 |
|
|
|
|
13328978 |
Dec 16, 2011 |
8740413 |
|
|
14256670 |
|
|
|
|
13019897 |
Feb 2, 2011 |
|
|
|
13328978 |
|
|
|
|
13014622 |
Jan 26, 2011 |
|
|
|
13328978 |
|
|
|
|
61424562 |
Dec 17, 2010 |
|
|
|
61301193 |
Feb 3, 2010 |
|
|
|
61357849 |
Jun 23, 2010 |
|
|
|
Current U.S.
Class: |
315/297 |
Current CPC
Class: |
F21V 19/006 20130101;
H01L 27/156 20130101; F21V 23/06 20130101; H01L 33/502 20130101;
F21K 9/235 20160801; H01L 33/60 20130101; H01L 2924/0002 20130101;
F21V 7/00 20130101; F21V 29/74 20150115; F21Y 2105/10 20160801;
F21Y 2105/12 20160801; F21K 9/232 20160801; F21K 9/00 20130101;
F21K 9/233 20160801; H01L 25/0753 20130101; H01L 33/505 20130101;
H01L 33/56 20130101; F21V 9/08 20130101; F21Y 2115/10 20160801;
H05B 45/10 20200101; F21V 3/00 20130101; H01L 33/504 20130101; F21Y
2101/00 20130101; F21K 9/60 20160801; F21Y 2113/13 20160801; F21V
29/70 20150115; H01L 2924/0002 20130101; H01L 2924/00 20130101 |
International
Class: |
F21V 9/08 20060101
F21V009/08; F21K 9/235 20060101 F21K009/235; F21V 19/00 20060101
F21V019/00; F21V 3/00 20060101 F21V003/00; H05B 33/08 20060101
H05B033/08; F21V 23/06 20060101 F21V023/06; H01L 25/075 20060101
H01L025/075; H01L 33/60 20060101 H01L033/60; H01L 33/56 20060101
H01L033/56; H01L 33/50 20060101 H01L033/50; F21V 29/74 20060101
F21V029/74; F21V 7/00 20060101 F21V007/00 |
Claims
1. A light-emitting system comprising: at least one first
light-emitting source configured to emit a first radiation, said
first radiation being blue light having a first wavelength; at
least one second light-emitting source configured to emit a second
radiation, said second radiation being violet light having a second
wavelength shorter than said first wavelength; one or more
wavelength-converting materials disposed to absorb at least a
portion of said first or second radiations, and configured to emit
a converted radiation having one or more wavelengths longer than
said first or second wavelengths such that said system emits
emitted light comprising a blend of two or more of said first,
second and converted radiations; and at least one driving circuit
for selectively powering said at least one first and second
light-emitting sources to adjust said blend of said emitted
light.
2. The system of claim 1, wherein said at least one driving circuit
is configured to be controlled to vary power to said at least one
first light-emitting source and said at least one second
light-emitting source, respectively.
3. The system of claim 1, wherein said at least one driving circuit
is configured to selectively brighten, dim, or turn off at least
one of said at least one first light-emitting source or said at
least one second light-emitting source based on a selected output
of said emitted light.
4. The system of claim 1, wherein said at least one driving circuit
is configured to vary power to one of said at least one first
light-emitting source or said at least one second light-emitting
source, while maintaining power to the other of said at least one
first light-emitting source or said at least one second
light-emitting source.
5. The system of claim 1 wherein said at least one driving circuit
is configured to power said at least one first light-emitting
source or said at least one second light-emitting source based on a
ratio of power being delivered to said at least one first
light-emitting source to power being delivered to said at least one
second light-emitting source.
6. The system of claim 1, wherein said at least one driving circuit
is configured to power said at least one first light-emitting
source and said at least one second light-emitting source such that
said emitted light has essentially a constant luminance.
7. The system of claim 1, wherein said at least one driving circuit
is configured to power said at least one first light-emitting
source and said at least one second light-emitting source such that
said emitted light has a color rendering index which is maintained
above a predetermined value.
8. The system of claim 1, wherein said at least one driving circuit
is configured to power said at least one first light-emitting
source and said at least one second light-emitting source such that
said emitted light has a color rendering index and a luminance
which are varied according to predetermined values.
9. The system of claim 1, wherein said at least one driving circuit
is configured to power, selectively, said at least one first
light-emitting source and said at least one second light-emitting
source at predetermined times.
10. The system of claim 1 wherein said emitted light comprises a
blend of only said first and converted radiations or a blend of
only said second and converted radiations.
11. The system of claim 1 wherein said wavelength-converting
material is disposed in patterned shapes.
12. The system of claim 11, further comprising more than one
patterned shapes, wherein said patterned shapes are optically
isolated from each other.
13. The system of claim 12, where said optical isolation is
provided by optical elements.
14. The system of claim 13, wherein said optical elements are
reflective elements disposed between said patterned shapes.
15. The system of claim 1, wherein said wavelength-converting
materials include a first material substantially emitting light in
a range of about 500 nm to about 600 nm and a second material
substantially emitting light in a range of about 600 nm to about
700 nm.
16. The system of claim 15, wherein said at least one first
light-emitting source comprises a plurality of said first
light-emitting sources, or said at least one second light-emitting
source comprises a plurality of second light-emitting sources, said
first and second light-emitting sources being configured with said
first and second materials in at least one of a first pattern or a
second pattern, in said first pattern, a first portion of said
first light-emitting sources is patterned with said first material
and a second portion of said first light-emitting sources is
patterned with said second material, said first and second portions
being different, and, in said second pattern, a third portion of
said second light-emitting sources is patterned with said first
material and a fourth portion of said second light-emitting sources
is patterned with said second material, said third and fourth
portions being different.
17. The system of claim 1 further comprising at least one third
light-emitting source configured to emit light having a third
wavelength within a range of about 600 nm to 660 nm.
18. The system of claim 1, wherein said at least one first
light-emitting source has a wavelength of 430 nm to about 490; and
wherein said at least one second light-emitting source has a
wavelength of greater than 405 nm.
19. The system of claim 1, further comprising an optical element
configured to suppress a fraction of said emitted light in a
predetermined wavelength range.
20. The system of claim 19, wherein said optical element is one or
more of a light-absorbing element, a light-reflecting element, or a
wavelength-converting element.
21. The system of claim 19, wherein said optical element is
positioned to selectively suppress a fraction of said emitted
light.
22. A light-emitting system comprising: at least one blue
light-emitting source; at least one violet light-emitting source;
one or more phosphors to absorb at least a portion of light from at
least one of said blue or violet light-emitting sources, and emit
light of one or more different wavelengths; and one or more drivers
for selectively driving said at least one blue and violet
light-emitting sources, said one or more drivers being configured
to brighten or dim said at least one blue light-emitting source
relative to said at least one violet light-emitting source, or to
turn off said at least one blue light-emitting source while
powering said at least one violet light-emitting source.
23. The system of claim 22, wherein said blue light-emitting source
has a wavelength of 420 nm to about 490; and wherein said violet
light-emitting source has a wavelength of 380 nm to about 430
nm.
24. A method of using a light-emitting device, said device
comprising at least one blue light-emitting source, at least one
violet light-emitting source, one or more phosphors to absorb at
least a portion of light from at least one of said blue or violet
light-emitting sources and emit light of one or more different
wavelengths, and one or more drivers for selectively driving a
first electrical power into said blue light-emitting source, and a
second electrical power into said violet light-emitting sources,
said method comprising: selectively driving said blue and said
violet light-emitting sources during a first period according to a
first ratio of said first power to said second power; and
selectively driving said blue and said violet light-emitting source
during a second period according to a second ratio of said first
power to said second power; wherein said first ratio is larger than
said second ratio.
25. The method of claim 24, wherein said device emits essentially
white light during said first and second periods.
26. The method of claim 24, wherein selectively driving said blue
and said violet light-emitting sources during said second period
comprises decreasing said first power relative to said second power
to obtain said second ratio.
27. The method of claim 26, wherein said second power remains
essentially the same for said first and second ratios.
28. A method of varying light output using a light-emitting device,
said device comprising at least one blue light-emitting source, at
least one violet light-emitting source, one or more phosphors, said
device emitting light having an emitted spectral power distribution
(SPD), said method comprising: operating said light-emitting device
during a first period such that a first fraction of said SPD is in
a wavelength range of about 430 nm to 490 nm; and operating said
light-emitting device during a second period such that a second
fraction of said SPD is in said wavelength range, wherein said
second fraction is less than said first fraction.
29. The method of claim 28, wherein said light-emitting device
comprises one or more drivers for selectively driving said blue and
violet light-emitting sources, and wherein operating said
light-emitting device during said second period comprises diming
said at least one blue emitting source relative to said at least
one violet light-emitting source, or turning off said at least one
blue light-emitting source while powering said at least one violet
light-emitting source.
30. The method of claim 28, wherein said light-emitting device
further comprises an optical element configured to suppress a
fraction of said first wavelength, and wherein operating said
light-emitting device during said second period comprises using
said optical element to block a portion of said first wavelength.
Description
[0001] This application is a continuation application of U.S.
application Ser. No. 14/531,545, filed on Nov. 3, 2014, which is a
continuation-in-part application of U.S. application Ser. No.
14/256,670, filed on Apr. 18, 2014, issued as U.S. Pat. No.
8,905,588, Dec. 19, 2014, which is a continuation application of
U.S. application Ser. No. 13/328,978, filed on Dec. 16, 2011,
issued as U.S. Pat. No. 8,740,413, on Jun. 3, 2014, which claims
the benefit under 35 U.S.C. .sctn.119(e) of U.S. Provisional
Application No. 61/424,562, filed on Dec. 17, 2010; and U.S.
application Ser. No. 13/328,978 is a continuation-in-part
application of U.S. application Ser. No. 13/019,987, filed on Feb.
2, 2011, which claims the benefit under 35 U.S.C. .sctn.119(e) of
U.S. Provisional Application No. 61/301,193, filed on Feb. 3, 2010;
and U.S. application Ser. No. 13/328,978 is a continuation-in-part
application of U.S. application Ser. No. 13/014,622, filed on Jan.
26, 2011, which claims the benefit under 35 U.S.C. .sctn.119(e) of
U.S. Provisional Application No. 61/357,849, filed on Jun. 23,
2010; each of which is incorporated by reference in its
entirety.
BACKGROUND
[0002] The present disclosure relates generally to light emitting
devices and, more particularly, to techniques for using wavelength
conversion materials with light emitting devices.
[0003] The present disclosure is directed to optical devices. The
disclosure provides a light source that includes two or more layers
of phosphor materials excited by radiation sources that emit
radiations in two or more wavelengths, with at least one of the
radiation wavelength less than 440 nm. In a specific embodiment
where LED radiation sources are used, LED radiation sources that
emit ultra-violet (UV), violet (V), or near-ultraviolet (NUV)
radiation are used to excite blue phosphor material. In various
embodiments, red and green phosphor materials are used and the LED
radiation sources are arranged in a specific pattern. In other
embodiments red, green, and blue phosphor materials are used.
[0004] In the late 1800's, Thomas Edison invented the light bulb.
The conventional light bulb, commonly called the "Edison bulb", has
been used for over one hundred years. The conventional light bulb
uses a tungsten filament enclosed in a glass bulb sealed in a base,
which is screwed into a socket. The socket is coupled to an AC
power or DC power source. The conventional light bulb can be found
commonly in houses, buildings, and outdoor lightings, and other
areas requiring light. Unfortunately, drawbacks exist with the
conventional Edison light bulb. That is, the conventional light
bulb dissipates much thermal energy. More than 90% of the energy
used for the conventional light bulb dissipates as thermal energy.
Additionally, the conventional light bulb eventually fails due to
evaporation of the tungsten filament.
[0005] Fluorescent lighting overcomes some of the drawbacks of the
conventional light bulb. Fluorescent lighting uses an optically
clear tube structure filled with a noble gas, and typically also
contains mercury. A pair of electrodes is coupled between the gas
and to an alternating power source through ballast to excite the
mercury. Once the mercury has been excited, it discharges, emitting
UV light. Typically, the optically clear tube is coated with
phosphors, which are excited by the UV light to provide white
light. Many building structures use fluorescent lighting and, more
recently, fluorescent lighting has been fitted onto a base
structure, which couples into a standard socket.
[0006] Solid state lighting techniques are also known. Solid state
lighting relies upon semiconductor materials to produce light
emitting diodes (LEDs). At first, red LEDs were used. Modern red
LEDs use Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor
materials. Most recently, Shuji Nakamura pioneered the use of InGaN
materials to produce LEDs emitting light in the blue color range
for LEDs. The blue light LEDs led to innovations such as solid
state white lighting, the blue laser diode, the Blu-Ray.TM. DVD
player, and other developments. Blue-, violet-, or
ultraviolet-emitting devices based on InGaN are used in conjunction
with phosphors to provide white LEDs. Other colored LEDs have also
been proposed.
[0007] One way of improving solid state light efficiency has been
to use phosphor converted LEDs (pcLED) technology, where an LED
emits radiation that excites phosphors, which in turn emit light.
Unfortunately, conventional pcLEDs have been inadequate, especially
for white light for general illumination applications. In
particular, blue-excited pcLED configurations have the challenge
that blue light leakage must be managed to provide a stable white
output. This is difficult because blue light leakage depends on the
peak emission wavelength, which shifts with drive current and
operating temperature. V- or NUV-excited pcLEDs avoid this problem,
but have performance disadvantages due to increased Stokes' loss,
as well as cascading conversion loss, since much of the V or NUV
light pumps blue phosphor, which then excites green and red
phosphors, rather than direct excitation of the green and red
phosphors.
[0008] Therefore, it is desirable to have improved techniques for
phosphor-based LED devices.
BRIEF SUMMARY
[0009] The present disclosure is directed to optical devices. The
disclosure provides a light source that includes two or more layers
of phosphor materials excited by radiation sources that emit
radiations in two or more wavelengths, with at least one of the
radiation wavelengths less than 440 nm. In a specific embodiment
where LED radiation sources are used, LED radiation sources that
emit ultra-violet (UV), violet (V), or near-ultraviolet (NUV)
radiation are used to excite blue phosphor material. In various
embodiments, red and green phosphor materials are used and the LED
radiation sources are arranged in a specific pattern. In other
embodiments, red, green, and blue phosphor materials are used.
[0010] In one embodiment, an optical device includes a submount
having a surface. The device includes a first plurality n of
radiation sources positioned on the surface configured to emit
radiation characterized by a first wavelength with a range between
about 380 nm to 470 nm. The device also includes a second plurality
m of radiation sources positioned on the surface configured to emit
radiation characterized by a second wavelength shorter than the
first wavelength. The ratio between m and n is based on a selected
wavelength. The device further includes a first wavelength
converting layer configured to absorb at least a portion of
radiation emitted by the first plurality of radiation sources and
the second plurality of radiation sources. The first wavelength
converting layer is associated with a wavelength emission ranging
from 590 nm to 650 nm. The device includes a second wavelength
converting layer configured to absorb at least a portion of
radiation emitted by the first plurality of radiation sources and
the second plurality of radiation sources. The second wavelength
converting layer is associated with a wavelength emission ranging
from 490 nm to 590 nm. The device additionally includes a third
wavelength converting layer configured to absorb at least a portion
of radiation emitted by the second plurality of radiation sources.
The third wavelength converting layer is associated with a
wavelength emission ranging from about 440 nm to about 490 nm.
[0011] In another embodiment, an optical device includes a submount
having a surface. The device also includes a first plurality n of
radiation sources configured to emit radiation characterized by a
first wavelength with a range between about 380 nm to 470 nm. The
device also includes a second plurality m of radiation sources
configured to emit radiation characterized by a second wavelength
shorter than the first wavelength. The second plurality of
radiation sources are positioned on the surface and arranged in a
specific pattern. The ratio between m and n is based on a selected
wavelength. The device also includes a first wavelength converting
layer associated with a wavelength emission ranging from 590 nm to
650 nm configured to absorb at least a portion of radiation emitted
by the first plurality of radiation sources and the second
plurality of radiation sources. The device further includes a
second wavelength converting layer associated with a wavelength
emission ranging from 490 nm to 590 nm configured to absorb at
least a portion of radiation emitted by the first plurality of
radiation sources and the second plurality of radiation sources.
The device also includes a phosphor pattern associated with a
wavelength emission ranging from 440 nm to 490 nm overlaying the
second plurality of radiation sources configured to absorb at least
a portion of radiation emitted by the second plurality of radiation
sources. A further understanding of the nature and advantages of
the present disclosure may be realized by reference to the latter
portions of the specification and attached drawings.
[0012] In certain aspects, optical devices are provided comprising:
an electrical connection to an external power source; a submount
comprising a mounting surface; at least one first light emitting
diode source, the at least one first light emitting diode source
configured to emit radiation characterized by a first wavelength
within a range from about 430 nm to about 480 nm, wherein the at
least one first light emitting diode source is disposed on the
mounting surface, and wherein the at least one first light emitting
diode source is electrically coupled to the electrical connection;
at least one second light emitting diode source configured to emit
radiation characterized by a second wavelength, the second
wavelength being shorter than the first wavelength, wherein the at
least one second light emitting diode source is disposed on the
mounting surface; and a first wavelength-converting material
positioned in an optical path of radiation from the at least one
first light emitting diode source and configured to convert
radiation from the first wavelength to radiation at a wavelength
within a range from about 500 nm to about 600 nm; wherein the
optical device is configured to output radiation from at least the
first light emitting diode source, the at least one second light
emitting diode source, and the first wavelength-converting
material.
[0013] In certain aspects, optical devices are provided comprising:
an electrical connection to an external power source; a submount
having disposed thereon a reflective pattern to form a mounting
surface; a plurality of first light emitting diode sources, at
least some of the plurality of first light emitting diode sources
configured to emit radiation characterized by a first wavelength
within a range from about 430 nm to about 480 nm, wherein the
plurality of first light emitting diode sources is disposed on the
mounting surface, and wherein the plurality of first light emitting
diode sources is electrically coupled to the electrical connection;
at least one second light emitting diode source configured to emit
radiation characterized by a second wavelength, the second
wavelength being shorter than the first wavelength, wherein the at
least one second light emitting diode source is disposed on the
mounting surface; a first wavelength-converting material positioned
in an optical path of radiation from at least one of the plurality
of first light emitting diode sources and configured to convert
radiation from the first wavelength to radiation at a wavelength
within a range from about 500 nm to about 600 nm; and a second
wavelength-converting material positioned in an optical path of
radiation from at least one of the plurality of first light
emitting diode sources and configured to convert radiation from the
first wavelength to radiation at a wavelength within a range from
about 590 nm to about 650 nm; wherein at least one of the plurality
of first light emitting diode sources is configured to excite
emission from at least one of the first wavelength-converting
material and the second wavelength-converting material; and wherein
at least one of the at least one second light emitting diode source
is configured to excite emission from at least one of the first
wavelength-converting material and the second wavelength-converting
material.
[0014] In certain aspects, lamps are provided comprising: a base,
the base having at least one structural member to provide a mount
point; an electrical connection to an external power source; a
submount having disposed thereon a reflective pattern to form a
mounting surface; a plurality of first light emitting diode
sources, at least some of the plurality of first light emitting
diode sources configured to emit radiation characterized by a first
wavelength within a range from about 430 nm to about 480 nm,
wherein the plurality of first light emitting diode sources is
disposed on the mounting surface, and wherein the at least one
first light emitting diode source is electrically coupled to the
electrical connection; at least one second light emitting diode
source configured to emit radiation characterized by a second
wavelength, the second wavelength being shorter than the first
wavelength, wherein the at least one second light emitting diode
source is disposed on the mounting surface; a first
wavelength-converting material positioned in an optical path of
radiation from at least one of the plurality of first light
emitting diode sources and configured to convert radiation from the
first wavelength to radiation at a wavelength within a range from
about 500 nm to about 600 nm; and a second wavelength-converting
material positioned in an optical path of radiation from at least
one of the plurality of first light emitting diode sources and
configured to convert radiation from the first wavelength to
radiation at a wavelength within a range from about 590 nm to about
650 nm; wherein at least one of the plurality of first light
emitting diode sources is configured to excite emission from at
least one of the first wavelength-converting material and the
second wavelength-converting material; and wherein at least one of
the at least one second light emitting diode source is configured
to excite emission from at least one of the at least one second
light emitting diode source, the first wavelength-converting
material, and the second wavelength-converting material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A is a simplified diagram illustrating a
chip-array-based pcLED apparatus with an RGB phosphor mix for
generating white light, according to an embodiment of the
disclosure.
[0016] FIG. 1B is a simplified diagram illustrating construction of
a radiation source comprised of light emitting diodes, according to
some embodiments.
[0017] FIG. 1C is a simplified diagram illustrating an optical
device embodied as a light source constructed using an array of
LEDs juxtaposed with a cover member, according to some
embodiments.
[0018] FIG. 1D is a simplified diagram illustrating an LED lamp
having a base to provide a mount point for a light source,
according to some embodiments.
[0019] FIG. 2 is a simplified diagram illustrating a
chip-array-based apparatus 200 having green and red wavelength
converting material, according to some embodiments.
[0020] FIG. 3A is a simplified diagram illustrating a conversion
process, according to some embodiments.
[0021] FIG. 3B is a simplified diagram illustrating a conversion
process, according to some embodiments.
[0022] FIG. 4 is a graph illustrating a light process chart by
phosphor material, according to some embodiments.
[0023] FIG. 5 is a simplified diagram illustrating an optical
device according to an embodiment of the present disclosure.
[0024] FIG. 6 is a simplified diagram illustrating an optical
device according to an embodiment of the present disclosure.
[0025] FIG. 7 is a simplified graph illustrating performance of
various embodiments of optical devices, according to embodiments of
the present disclosure.
[0026] FIG. 8 is a simplified diagram illustrating an optical
device having violet and blue LEDs according to an embodiment of
the present disclosure.
[0027] FIG. 9 is a simplified diagram illustrating an optical
device having violet and patterned blue LEDs according to an
embodiment of the present disclosure.
[0028] FIG. 10 is a simplified diagram illustrating an optical
device having violet and red LEDs according to an embodiment of the
present disclosure.
[0029] FIG. 11 is a simplified diagram illustrating an optical
device having violet and red LEDs according to an embodiment of the
present disclosure.
[0030] FIG. 12A is a simplified diagram illustrating an optical
device having red, green, and blue LEDs disposed within recesses,
according to an embodiment of the present disclosure.
[0031] FIG. 12B is a simplified diagram illustrating an optical
device having red, green, and blue LEDs disposed between barriers,
according to an embodiment of the present disclosure.
[0032] FIG. 13 is an exploded view of an LED lamp, according to
some embodiments.
[0033] FIG. 14 is an illustration of an LED system comprising an
LED lamp, according to an embodiment of the present disclosure.
[0034] FIG. 15 is a block diagram of a system to perform certain
operations to fabricate an optical device, according to an
embodiment of the present disclosure.
DETAILED DESCRIPTION
[0035] Various types of phosphor-converted (pc) light-emitting
diodes (LEDs) have been proposed in the past. Conventional pcLEDs
include a blue LED with a yellow phosphor. UV or V-based
phosphor-converted (pc) LEDs exhibit certain advantages in
performance (compared to blue-pumped pcLEDs) such as high color
rendering (broadband spectrum comprising phosphor emission) and
accurate color control (e.g., as the violet "pump" light
contributes little to the chromaticity).
[0036] FIG. 1A is a simplified diagram illustrating a
chip-array-based pcLED apparatus with an RGB phosphor mix for
generating white light. As shown in FIG. 1A, the pcLED apparatus
100 includes three layers of phosphor materials: blue phosphor
material 104, red phosphor material 103, and green phosphor
material 102. The phosphor materials are excited by radiations
emitted by LED devices (e.g., LED device 101). As an example, the
LED devices are each nominally monochromatic and emit in a similar
wavelength range.
[0037] FIG. 1B is a simplified diagram illustrating construction of
a radiation source comprised of light emitting diodes. As shown,
the radiation source 120 constructed on a submount 111 upon which
submount is a layer of sapphire or other insulator 112, upon which,
further, are disposed one or more conductive contacts (e.g.,
conductive contact 114.sub.1, conductive contact 114.sub.2),
arranged in an array where each conductive contact is spatially
separated from any other conductive contact by an isolation gap
116. FIG. 1B shows two conductive contacts in a linear array,
however other arrays are possible, and are described herein. Atop
the conductive contacts are LED devices (e.g., LED device
115.sub.1, LED device 115.sub.2, LED device 115.sub.N, etc.). The
LED device is but one possibility for a radiation source, and other
radiation sources are possible and envisioned, for example a
radiation source can be a laser device.
[0038] In a specific embodiment, the devices and packages disclosed
herein include at least one non-polar or at least one semi-polar
radiation source (e.g. an LED or laser) disposed on a submount. The
starting materials can comprise polar gallium nitride containing
materials.
[0039] The radiation source 120 is not to be construed as
conforming to a specific drawing scale, and in particular, many
structural details are not included in FIG. 1B so as not to obscure
understanding of the embodiments. In particular, the dimensions of
the isolation gap of FIG. 1B serves to separate the conductive
contacts (e.g., conductive contact 114.sub.1, conductive contact
114.sub.2) one from another, and in some embodiments, the isolation
is relatively wider, or deeper, or shorter or shallower. The
isolation gap serves to facilitate shaping of materials formed in
and around the isolation gap, which formation can be by one or more
additive processes, or by one or more subtractive processes, or
both. The aforementioned shaped materials serve as an isolation
barrier. Further details are presented infra.
[0040] It is to be appreciated that the radiation sources
illustrated in FIG. 1B can output light in a variety of wavelengths
(e.g., colors) according to various embodiments of the present
disclosure. Depending on the application, color balance can be
achieved by modifying color generated by LED devices using a
wavelength-modifying material (e.g., a phosphor material). In one
embodiment, the phosphor material may be mixed with encapsulating
material (e.g., silicone material) that distributes phosphor color
pixels within a thin layer atop the array of LED devices. Other
embodiments for providing color pixels can be conveniently
constructed using a cover member (see FIG. 1C) that comprises
deposits of one or more wavelength-modifying materials.
[0041] FIG. 1C is a simplified diagram illustrating an optical
device 150 embodied as a light source 142 constructed using an
array of LEDs juxtaposed with a cover member 140, the cover member
having a mixture of wavelength converting materials distributed
within the volume of the cover member, according to some
embodiments. The wavelength converting materials can be distributed
in a variety of configurations. For example, the light source 142
can include blue color emitting material at its corners, green
color emitting material at its edges, and red color emitting
material at its center. Individually, and together, these color
pixels modify the color of light emitted by the LED devices. For
example, the color pixels are used to modify the light from LED
devices to appear as white light having a uniform broadband
emission (e.g., characterized by a substantially flat emission of
light throughout the range of about 380 nm to about 780 nm), which
is suitable for general lighting. In one embodiment, "blank" pixels
are used for later color tuning and the color of the light from LED
devices is measured.
[0042] In various embodiments, color balance adjustment is
accomplished by using pure color pixels, mixing phosphor material,
and/or using a uniform layer of phosphor over LED devices. In one
embodiment, color balance tuning is achieved by providing a color
pattern on a cover member 140. Or, the cover member can be is made
of glass material and function as a 405 nm reflection dichroic
lens. Hermetic sealing techniques may be used to encapsulate the
cover member within the optical device 150. A color tuning using
cover member can also be achieved through light absorption and/or
light reflection.
[0043] In one embodiment, a predeposited phosphor plate is attached
to the cover member based on a predetermined pattern. For example,
after positioning wavelength-modifying material in the vicinity of
the light emitting devices, the color of the aggregate emitted
light by the optical device 150 is measured. Based on the measured
color, the positioning of the wavelength-modifying material is
determined and used to balance the color of the aggregate emitted
light. Various wavelength converting processes are discussed
infra.
[0044] In an alternative embodiment, wavelength converting
processes are facilitated by using one or more pixilated phosphor
plates that are attached to the cover member. For example, the
pixilated phosphor plates include color and, depending on the
application, color patterns of the phosphor plate may be
predetermined based on the measured color balance of the aggregate
emitted light. In an alternative embodiment, the absorption plate,
which is attached to the cover member, is used to perform color
correction. In some situations, the absorption plate comprises
color absorption material. For example, the absorbing and/or
reflective material can be plastic, ink, die, glue, epoxy, and
others.
[0045] In other embodiments, the phosphor particles are embedded in
a reflective matrix (e.g., the matrix formed by conductive
contacts). Such phosphor particles can be disposed on the substrate
by deposition. In one specific embodiment, the reflective matrix
comprises silver or other suitable material. Alternatively, one or
more colored pixilated reflector plates (not shown) are attached to
the cover member to adjust color balance of the LED devices. In
some situations, materials such as aluminum, gold, platinum,
chromium, and/or others are deposited on the pixilated reflector
plates to provide color balance.
[0046] FIG. 1D is a simplified diagram illustrating an LED lamp 160
having a base to provide a mount point for a light source,
according to some embodiments. It is to be appreciated that an LED
lamp 160, according to the present disclosure, can be implemented
for various types of applications. As shown in FIG. 1D, a light
source (e.g., the light source 142) is a part of the LED lamp 160.
The LED lamp 160 includes a base member 151. The base member 151 is
mechanically connected to a heat sink 152. In one embodiment, the
base member 151 is compatible with conventional light bulb socket
and is used to provide electrical power (e.g., using an AC power
source) to the one or more radiation emitting devices (e.g., one or
more instances of light source 142).
[0047] FIG. 2 is a simplified diagram illustrating a
chip-array-based apparatus 200 having green and red wavelength
converting material. Compared to the device shown in FIG. 1A, only
two layers of wavelength converting materials are used. This
example shows a transparent (non-converting layer) as well as a
layer of green wavelength converting materials 202 and a layer of
red wavelength converting materials 204. The LED devices (e.g., LED
device 201) comprising the array are blue-emitting. The combination
of blue LED light emission and the green and red wavelength
converting materials emission results in white light.
[0048] FIG. 3A is a simplified diagram illustrating a conversion
process 300. As shown, a radiation source 301 is configured to emit
radiation at violet, near ultraviolet, or UV wavelengths. The
radiation emitted by radiation source 301 is absorbed by the
phosphor materials (e.g., the blue phosphor material 302, the green
phosphor material 303, and the red phosphor material 304). Upon
absorbing the radiation, the blue phosphor material 302 emits blue
light, the green phosphor material 303 emits green light, and the
red phosphor material 304 emits red light. As shown, a portion
(e.g., portion 310.sub.1, portion 310.sub.2) of the emissions from
the blue phosphor are incident on the surrounding phosphors, and
are absorbed by the green phosphor material and red phosphor
material, which emits green and red light, respectively. This
particular process of converted blue light being further absorbed
and converted (e.g., in a cascade of emission and absorption) is
considered a lossy process, and in some cases can be
undesirable.
[0049] FIG. 3B is a simplified diagram illustrating a conversion
process 350. As shown, a radiation source 351 is configured to emit
radiation at a wavelength that is substantially in the blue
spectrum. The radiation emitted by radiation source 351 is
reflected by blue light emitting wavelength converting material 352
and absorbed by the green light emitting wavelength converting
material 353 and red light emitting wavelength converting material
354. Upon absorbing the radiation, green light emitting wavelength
converting material 353 emits green light, and the red light
emitting wavelength converting material 354 emits red light. A
portion of the converted blue light is absorbed by the green light
emitting wavelength converting material and red light emitting
wavelength converting material, which emits green and red light,
respectively. This particular process of converted blue light being
further absorbed and converted is considered a lossy process, and
in some cases can be undesirable.
[0050] FIG. 4 is a graph illustrating a light process chart 400 by
phosphor material. As shown in FIG. 4, radiation with a wavelength
of violet, near violet, or ultraviolet from a radiation source is
absorbed by the blue phosphor material, which in turn emits blue
light. However, since the blue color light can also be absorbed by
red and green phosphor, a portion of the blue light is converted to
green or red light. As shown in FIG. 4, each phosphor is most
effective at converting radiation at its particular range of
wavelength. And, as shown, some of these ranges overlap. In
particular, the wavelength range from about 380 nm to about 430 nm
(shown as wavelength range 411) exhibits absorption by all three
phosphors (e.g., blue, green, and red). However, the wavelength
range from about 430 nm to about 500 nm (shown as wavelength range
419) exhibits absorption by substantially only two phosphors (e.g.,
green, and red). Thus, the effect of the lossy conversion processes
(e.g., conversion process 300 and conversion process 350) in
absorbing blue light from the radiation sources, and re-absorbing
blue-emitted light from the wavelength converting materials, is
reduced.
[0051] Yet, it remains a challenge with UV- or V-pumped embodiments
(e.g., pcLEDs) where there remains a requirement for a short pump
wavelength to excite a blue phosphor while reducing the lossy
effects as heretofore described. Among other challenges, the short
wavelength light is susceptible to optical loss in materials
typically employed in the fabrication of LEDs including GaN
semiconductor material, packaging material, contacts and
metallization (especially Ag) material, and encapsulation material
(e.g., silicone or epoxy). Furthermore, short wavelength LEDs that
pump a blue phosphor may generate blue photons which subsequently
pump lower-energy phosphors (e.g., green and red), as illustrated
in FIG. 4. This cascading event is lossy, according to the quantum
efficiency of the blue phosphor, thereby reducing color conversion
efficiency. It is thus desirable to maintain the benefits of UV-
and/or V-based LEDs while maintaining high conversion
efficiency.
[0052] It is to be appreciated that embodiments of the present
disclosure maintain the benefits of UV- and/or V-pumped pcLEDs
while improving conversion efficiency. In one embodiment, an array
of LED chips is provided, and is comprised of two groups. One group
of LEDs has a shorter wavelength to enable pumping of a blue
phosphor material. The second group of LEDs has a longer wavelength
which may, or may not, excite a blue phosphor material, but will
excite a green or longer wavelength (e.g., red) phosphor material.
For example, the first group of LEDs might have an average emission
wavelength of less than 405 nm, while the second group may have an
average emission wavelength greater than 405 nm. The combined
effect of the two groups of LEDs in the array is to provide light
of desired characteristics such as color (e.g., white) and color
rendering. Furthermore, the conversion efficiency achieved in the
preferred embodiment will be higher than that of the conventional
approach. In particular, the cascading loss of blue photons pumping
longer-wavelength phosphors may be reduced by localizing blue
phosphor to regions near the short-wavelength LEDs. In addition,
the longer-wavelength pump LEDs will contribute to overall higher
efficacy by being less susceptible to optical loss mechanisms in
GaN, metallization, and packaging materials, as described
above.
[0053] FIG. 5 is a simplified diagram illustrating an optical
device, according to an embodiment of the present disclosure. As
shown in FIG. 5, an optical device 500 includes a submount 111 (not
shown) that has a surface. A number of radiation sources are
provided on the submount. According to various embodiments, two
types of radiation sources are provided, and each type of radiation
source is associated with a range of wavelength. For example,
radiation sources include a first plurality of radiation sources
that are configure to emit radiation characterized by a first
wavelength. More specifically, the first wavelength can have a
range of between about 380 nm to 470 nm. In a specific embodiment,
the first wavelength is characterized by a peak emission of about
420 nm to 470 nm. The first plurality of radiation sources is
positioned on the surface, and the first plurality of radiation
sources comprising n number of radiation sources. For example, the
first plurality of radiation sources includes "long" violet LED
devices 501 and 506.
[0054] The radiation sources also include a second plurality of
radiation sources that are configured to emit radiation
characterized by a second wavelength. In exemplary embodiments, the
second wavelength is shorter than the first wavelength. More
specifically, the second wavelength is violet or ultraviolet. In a
specific embodiment, the second plurality of radiation sources is
characterized by a peak emission in the range of about 380 nm to
about 430 nm. In a certain embodiment, the second wavelength is
less than 390 nm. The second plurality of radiation sources is
positioned on the surface of the submount. The second plurality of
radiation sources includes m number of radiation sources. The ratio
between the number m and the number n is predetermined based on a
selected wavelength. Typically, for warm color temperatures, n is
greater than m. The ratio of n to m can be 1:1, 2:1, 10:1, and
other ratios. For example, the ratio can be based on a selected
wavelength output for the optical device 500. As an example, the
second plurality of radiation sources comprises LED devices 505 and
507.
[0055] Depending on the application, the arrangement of a first
plurality and a second plurality of radiation sources can be based
on various criteria. For example, particular patterns can be used
to maximize the efficiency of the optical device 500.
[0056] The optical device 500 includes three wavelength converting
layers overlaying the radiation sources: a first wavelength
converting layer 503, a second wavelength converting layer 502, and
a third wavelength converting layer 504. The first wavelength
converting layer 503 is configured to absorb at least a portion of
radiation emitted by both the first plurality of radiation sources
and the second plurality of radiation sources. More specifically,
the first wavelength converting layer is associated with a
wavelength emission ranging from 590 nm to 650 nm. For example, the
first wavelength converting layer comprises red phosphor material
that is adapted to emit substantially red color light.
[0057] The second wavelength converting layer 502 is configured to
absorb at least a portion of radiation emitted by the first
plurality of radiation sources and the second plurality of
radiation sources. The second wavelength converting layer is
associated with a wavelength emission ranging from 490 nm to 590
nm. For example, the second wavelength converting layer comprises a
green phosphor that is adapted to emit substantially green
light.
[0058] The third wavelength converting layer 504 is configured to
absorb at least a portion of radiation emitted by the second
plurality of radiation sources. The third wavelength converting
layer is associated with a wavelength emission ranging from 440 nm
to 490 nm. For example, the third wavelength converting layer
comprises a blue phosphor material that is adapted to emit
substantially blue light.
[0059] Depending on the application, the optical device 500 may
include other components as well. In certain embodiments, the
optical device 500 includes a power source that is capable of
selectively powering the radiation sources or LED devices. In a
specific embodiment, the power source is configured to turn
radiation sources on and off based on the desired color output. For
example, by selectively turning off the radiation source of a
specific wavelength, the color output of the optical device is
changed. More particularly, a driving circuit can be configured to
selectively power the first plurality of radiation devices while
maintaining a constant power to the second plurality of radiation
sources. Or, the driving circuit can be configured to tune to a
ratio of energy being delivered to the first plurality of radiation
sources as compared to energy delivered to the second plurality of
radiation sources.
[0060] In certain embodiments, the power source is configured to
turn off certain radiation sources for dimming purposes. The
optical device 500 can also include other components such as a
housing member, sealing material, transparent cover, encapsulating
material, and others. And, in certain embodiments, patterned
phosphor materials are used.
[0061] FIG. 6 is a simplified diagram illustrating an optical
device 600, according to an embodiment of the present disclosure.
As shown in FIG. 6, an optical device 600 includes a submount 111
(not shown) that has a surface. A number of radiation sources are
provided on the submount. According to various embodiments, two
types of radiation sources are provided, and each type of radiation
source is associated with a range of wavelength. For example,
radiation sources include a first plurality of radiation sources
that are configured to emit radiation characterized by a first
wavelength. More specifically, the first wavelength can have a
range of between about 380 nm to 470 nm. In a specific embodiment,
the first wavelength is characterized by a peak emission at about
420 nm to 470 nm. The first plurality of radiation sources are
positioned on the surface. The first plurality of radiation sources
have an n number of radiation sources. For example, the first
plurality of radiation sources includes LED devices 604 and
605.
[0062] The radiation sources of optical device 600 also include a
second plurality of radiation sources that are configured to emit
radiation characterized by a second wavelength. In various
embodiments, the second wavelength is shorter than the first
wavelength. More specifically, the second wavelength is violet or
ultraviolet. In a specific embodiment, the second plurality of
radiation sources are characterized by a peak emission in the range
of about 380 nm to about 430 nm. In certain embodiments, the second
wavelength is less than 390 nm. The second plurality of radiation
sources is positioned on the surface of the submount. The second
plurality of radiation sources comprises m number of radiation
sources. The ratio between m and n is predetermined based on a
selected wavelength. Typically, n is greater than m. The ratio of n
to m can be 1:1, 2:1, 10:1, and other ratios. For example, the
ratio is based on a selected wavelength output for the optical
device 500. As an example, the second plurality of radiation
sources comprises short violet LED devices 603 and 606.
[0063] In various embodiments, the arrangement of the radiation
sources is patterned. More specifically, the locations of the
second plurality of radiation sources are predetermined and are
covered and/or surrounded by a specific phosphor pattern (e.g.,
phosphor pattern 607.sub.1, phosphor pattern 607.sub.1). The
phosphor pattern is configured to be proximal to instances from
among the second plurality of radiation sources. More specifically,
the phosphor pattern is more remote from the first plurality of
radiation sources. The phosphor pattern is configured to absorb at
least a portion of radiation emitted by the second plurality of
radiation sources. In various embodiments, the phosphor pattern is
associated with a wavelength emission ranging from about 440 nm to
about 490 nm. In a specific embodiment, the phosphor pattern
comprises blue phosphor material. For example, the patterned blue
phosphor material is used to convert violet or ultraviolet
radiation to blue light. Among other things, the blue light
converted by the patterned phosphor material can help create
desired color balance and improve efficiency.
[0064] As shown, the optical device 600 also includes a first
wavelength converting layer 601 configured to absorb at least a
portion of radiation emitted by the first plurality of radiation
sources and the second plurality of radiation sources. The first
wavelength converting layer is associated with a wavelength
emission ranging from 590 nm to 650 nm. For example, the first
wavelength converting layer comprises red phosphor material that is
adapted to emit substantially red color light.
[0065] The second wavelength converting layers 601 and 602 are
configured to absorb at least a portion of radiation emitted by the
first plurality of radiation sources and the second plurality of
radiation sources. The second wavelength converting layer is
associated with a wavelength emission ranging from 490 nm to 590
nm. For example, the second wavelength converting layer comprises a
green phosphor that is adapted to emit substantially green
light.
[0066] As an example, the first and second wavelength converting
layer can absorb radiation from both the first plurality and second
plurality of radiation sources. Additionally, the first and second
wavelength converting layers may also absorb emission from the
phosphor pattern. It is to be appreciated that the embodiments of
the present disclosure can provide efficiency gains over
conventional techniques.
[0067] FIG. 7 is a simplified graph 700 illustrating performance of
various embodiments of the optical devices described herein.
[0068] It is to be appreciated that the improvement in efficiency
can be dramatic. The data shown in FIG. 7 indicates a +20% gain in
conversion efficiency by pumping a tri-color phosphor mix with 405
nm radiating LEDs vs. 395 nm LEDs. In this comparison, the blue
phosphor material is likely to be equally excited by both 395 nm
and 405 nm LEDs, meaning the cascading loss of blue photons pumping
green and/or red phosphors is still present. So, even higher gains
are expected in cases for which a second group of LEDs is of a
sufficiently long wavelength to not substantially pump the blue
phosphor material.
[0069] FIG. 8 is a simplified diagram illustrating an optical
device 800 having violet and blue LEDs according to an embodiment
of the present disclosure. As shown in FIG. 8, violet LEDs and blue
LEDs are arranged according to a predetermined pattern. In this
configuration, green emitting and red emitting wavelength
converting materials are used to convert radiation emitted by
violet and blue LEDs. For example, the blue LEDs as shown are
configured to provide blue color light, and as a result blue
phosphor material is not needed for the optical system to produce
white light.
[0070] One exemplary embodiment in accordance with the depiction of
FIG. 8 comprises an optical device 800 comprising a submount having
a surface, upon which surface is disposed a first plurality of
radiation sources configured to emit radiation characterized by a
first wavelength, the first wavelength having a range of about 440
nm to about 500 nm (e.g., radiating blue light), the first
plurality of radiation sources being positioned on the surface, and
the first plurality of radiation sources having n number of
radiation sources. A second plurality of radiation sources
configured to emit radiation is characterized by a second
wavelength, the second wavelength being shorter than the first
wavelength (e.g., radiating violet light), the second plurality of
radiation source being positioned on the surface, and the second
plurality of radiation sources having m number of radiation
sources, where a ratio between m and n is predetermined based on a
selected wavelength. Further, this embodiment comprises two layers
of wavelength converting material, namely a first wavelength
converting layer configured to absorb at least a portion of
radiation emitted by the second plurality of radiation sources, the
first wavelength converting layer having a wavelength emission
ranging from about 590 nm to about 650 nm (e.g., red emissions),
and a second wavelength converting layer configured to absorb at
least a portion of radiation emitted by the second plurality of
radiation sources, the second wavelength converting layer having a
wavelength emission ranging from about 490 nm to about 590 nm
(e.g., green emissions).
[0071] FIG. 9 is a simplified diagram illustrating an optical
device 900 having violet and patterned blue LEDs according to an
embodiment of the present disclosure. As shown in FIG. 9, violet
LEDs and blue LEDs are arranged according to a predetermined
pattern. For example, violet LEDs are characterized by a wavelength
emission ranging from about 380 nm to about 430 nm, and the blue
LEDs are characterized by a wavelength of about 420 nm to 490 nm.
In this configuration, green phosphor materials 902 and red
phosphor materials 901 are used to convert radiation emitted by
violet and blue LEDs. Moreover, the blue LEDs as shown are
configured to provide blue color light, and as a result blue
phosphor material is not needed for the optical system to produce
white light. For example, the blue LEDs are provided at
predetermined locations (e.g., predetermined location 910.sub.1,
predetermined location 910.sub.2, and predetermined location
910.sub.3) that are substantially remote from green and red
phosphor material, which allows the blue LEDs to efficiently emit
blue colored light that contributes to white light output. In some
embodiments, the blue LEDs are provided at predetermined locations
that are substantially surrounded by isolation barriers (e.g.,
isolation barrier 911.sub.1, isolation barrier 911.sub.2) such that
the blue LEDs emit blue colored light that does not substantially
interact with the green- and red-emitting wavelength converting
materials.
[0072] FIG. 10 is a simplified diagram illustrating an optical
device 1000 having violet and red LEDs according to an embodiment
of the present disclosure. As shown in FIG. 10, violet LEDs and red
LEDs are arranged according to a predetermined pattern. For
example, violet LEDs are characterized by a wavelength emission
ranging from about 380 nm to about 430 nm, and the red LEDs are
characterized by a wavelength of about 590 nm to 650 nm. In this
configuration, green and blue phosphor materials are used to
convert radiation emitted by violet and red LEDs. For example, the
red LEDs as shown are configured to provide red color light, and as
a result red phosphor material is not needed for the optical system
to produce white light. For example, red light combines with blue
and green light from blue and green phosphor material to form white
light.
[0073] FIG. 11 is a simplified diagram illustrating an optical
device 1100 having violet and red LEDs according to an embodiment
of the present disclosure. As shown in FIG. 11, violet LEDs and red
LEDs are arranged according to a predetermined pattern. For
example, violet LEDs are characterized by a wavelength emission
ranging from 380 nm to 430 nm, and the red LEDs are characterized
by a wavelength of about 590 nm to 650 nm. In this configuration,
green and blue phosphor materials are used to convert radiation
emitted by violet and red LEDs. For example, the red LEDs as shown
are configured to provide red color light, and as a result red
phosphor material is not needed for the optical system to produce
white light. In this example, red light combines with blue and
green light from blue and green phosphor material to form white
light.
[0074] In yet another embodiment, violet LEDs and red LEDs are
arranged according to a predetermined pattern. For example, violet
LEDs are characterized by a wavelength emission ranging from 380 nm
to 430 nm, and the red LEDs are characterized by a wavelength of
about 590 nm to 650 nm. In this configuration, green and blue
wavelength-emitting materials are used to convert radiation emitted
by violet LEDs. For example, the red LEDs as shown are configured
to provide red color light, and as a result red wavelength-emitting
material is not needed for the optical system to produce white
light. For example, red light combines with blue and green light
from blue and green wavelength-emitting material to form white
light.
[0075] FIG. 12A is a simplified diagram 1200 illustrating an
optical device having red, green, and blue radiation sources
disposed within recesses. In embodiments wherein portions of the
final white light spectrum are contributed by direct emission from
radiation sources, it is desirable to avoid interaction of such
direct emission with any wavelength converting materials (e.g.,
down-conversion materials, phosphors). For example, for
blue-emitting radiation sources whose spectra are being combined
with other radiation sources that are pumping to longer wavelength
down-conversion media (e.g., to make broader spectrum light), the
down-conversion media can be isolated from the optical path of the
blue-emitting LEDs. And, providing such an isolation (e.g., using
an isolation barrier) increases efficiency as there are losses
(e.g., backscattered light into LED chip) associated with
down-conversion. Instead, it is preferable to provide optical means
(e.g., an isolation barrier) to reflect light from the radiation
sources towards the desired optical far-field such that this
reflected light does not substantially interact with
down-conversion media.
[0076] One such an embodiment is shown in FIG. 12A. As shown, LEDs
are placed into recessed regions in a submount (e.g., substrate or
package) such that they are optically isolated from one another.
Further, light from direct-emitting LEDs does not interact with
down-conversion media and instead, is substantially directed into
the desired emission pattern of the entire LED package. Conversely,
light from the down-converted LEDs (e.g., down-converting LED
1204.sub.1, down-converting LED 1204.sub.2) is converted locally
and directed to the final emission pattern. In addition to
providing efficient light collection from the direct-emitting LEDs,
this design avoids cascading down-conversion events (e.g., violet
down-converted to green, and green down-converted to red) which can
unnecessarily reduce overall efficiency since quantum yields of
down-conversion media are less than 100%.
[0077] Light from the individual LEDs are combined together in the
far field to provide a uniform broadband emission which is a
combination of light from the direct-emitting and down-converting
LED chips.
[0078] FIG. 12B is a simplified diagram illustrating an optical
device having red, green, and blue LEDs disposed between barriers.
In the embodiment of FIG. 12B, the same benefits pertaining to
disposition of radiation sources in proximity to isolation barriers
are provided by fabrication of the isolation barriers using an
additive, rather than subtractive process. In an additive
processes, the barrier is formed by techniques such as overmolding,
deposition/lithography/removal, attachment of a barrier mesh, etc.
In subtractive processes, the recesses are formed by techniques
such as deposition/lithography/removal and other techniques well
known in the art.
[0079] The radiation sources can be implemented using various types
of devices, such as light emitting diode devices or laser diode
devices. In certain embodiments, the LED devices are fabricated
from gallium and nitrogen submounts, such as GaN submount. As used
herein, the term GaN submount is associated with Group III-nitride
based materials including GaN, InGaN, AlGaN, or other Group III
containing alloys or compositions that are used as starting
materials. Such starting materials include polar GaN submounts
(e.g., submount 111 where the largest area surface is nominally an
(h k l) plane wherein h=k=0, and l is non-zero), non-polar GaN
submounts (e.g., submount material where the largest area surface
is oriented at an angle ranging from about 80-100 degrees from the
polar orientation described above towards an (h k l) plane wherein
l=0, and at least one of h and k is non-zero), or semi-polar GaN
submounts (e.g., submount material where the largest area surface
is oriented at an angle ranging from about +0.1 to 80 degrees or
110-179.9 degrees from the polar orientation described above
towards an (h k l) plane wherein l=0, and at least one of h and k
is non-zero).
[0080] Wavelength conversion materials can be crystalline (single
or poly), ceramic or semiconductor particle phosphors, ceramic or
semiconductor plate phosphors, organic or inorganic downconverters,
upconverters (anti-stokes), nano-particles and other materials
which provide wavelength conversion. Major classes of downconverter
phosphors used in solid-state lighting include garnets doped at
least with Ce.sup.3+; nitridosilicates, oxynitridosilicates or
oxynitridoaluminosilicates doped at least with Ce.sup.3+;
chalcogenides doped at least with Ce.sup.3+; silicates or
fluorosilicates doped at least with Eu.sup.2+; nitridosilicates,
oxynitridosilicates, oxynitridoaluminosilicates or sialons doped at
least with Eu.sup.2+; carbidonitridosilicates or
carbidooxynitridosilicates doped at least with Eu.sup.2+;
aluminates doped at least with Eu.sup.2+; phosphates or apatites
doped at least with Eu.sup.2+; chalcogenides doped at least with
Eu.sup.2+; and oxides, oxyfluorides or complex fluorides doped at
least with Mn.sup.4+. Some specific examples are listed below:
(Ba,Sr,Ca,Mg).sub.5(PO.sub.4).sub.3(Cl,F,Br,OH):Eu.sup.2+,
Mn.sup.2+
(Ca,Sr,Ba).sub.3MgSi.sub.2O.sub.8:Eu.sup.2+, Mn.sup.2+
(Ba,Sr,Ca)MgAl.sub.10O.sub.17:Eu.sup.2+, Mn.sup.2+
(Na,K,Rb,Cs).sub.2[(Si,Ge,Ti,Zr,Hf,Sn)F.sub.6]:Mn.sup.4+
(Mg,Ca,Zr,Ba,Zn)[(Si,Ge,Ti,Zr,Hf,Sn)F.sub.6]:Mn.sup.4+
(Mg,Ca,Sr,Ba,Zn).sub.2SiO.sub.4:Eu.sup.2+
(Sr,Ca,Ba)(Al,Ga).sub.2S.sub.4:Eu.sup.2+
(Ca,Sr)S:Eu.sup.2+,Ce.sup.3+
(Y,Gd,Tb,La,Sm,Pr,Lu).sub.3(Sc,Al,Ga).sub.5O.sub.12:Ce.sup.3+
[0081] a group:
Ca.sub.1-xAl.sub.x-xySi.sub.1-x+xyN.sub.2-x-xyC.sub.xy:A (1);
Ca.sub.1-x-zNa.sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xyC.sub.xy-
:A (2);
M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xyC.s-
ub.xy:A (3);
M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w-
/3C.sub.xyO.sub.w-v/2H.sub.v:A (4); and
M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xy-2w-
/3-v/3C.sub.xyO.sub.wH.sub.v:A (4a),
[0082] wherein 0<x<1, 0<y<1, 0.ltoreq.z<1,
0.ltoreq.v<1, 0<w<1, x+z<1, x>xy+z, and
0<x-xy-z<1, M(II) is at least one divalent cation, M(I) is at
least one monovalent cation, M(III) is at least one trivalent
cation, H is at least one monovalent anion, and A is a luminescence
activator doped in the crystal structure.
Ce.sub.x(Mg,Ca,Sr,Ba).sub.y(Sc,Y,La,Gd,Lu).sub.1-x-yAl(Si.sub.6-z+yAl.su-
b.z-y)(N.sub.10-zO.sub.z) (where x,y<1, y.gtoreq.0 and
z.about.1)
(Mg,Ca,Sr,Ba)(Y,Sc,Gd,Tb,La,Lu).sub.2S.sub.4:Ce.sup.3+
(Ba,Sr,Ca).sub.xxSi.sub.yN.sub.z:Eu2+ (where 2x+4y=3z)
(Y,Sc,Lu,Gd).sub.2-nCa.sub.nSi.sub.4N.sub.6+nC.sub.1-n:Ce.sup.3+,
(wherein 0.ltoreq.n.ltoreq.0.5)
(Lu,Ca,Li,Mg,Y) alpha-SiAlON doped with Eu.sup.2+ and/or
Ce.sup.3+
(Ca,Sr,Ba)SiO.sub.2N.sub.2:Eu.sup.2+,Ce.sup.3+
(Sr,Ca)AlSiN.sub.3:Eu.sup.2+
CaAlSi(ON).sub.3:Eu.sup.2+
(Y,La,Lu)Si.sub.3N.sub.5:Ce.sup.3+
(La,Y,Lu).sub.3Si.sub.6N.sub.11:Ce.sup.3+
[0083] For purposes of the application, it is understood that when
a phosphor has two or more dopant ions (i.e. those ions following
the colon in the above phosphors), this is to mean that the
phosphor has at least one (but not necessarily all) of those dopant
ions within the material. That is, as understood by those skilled
in the art, this type of notation means that the phosphor can
include any or all of those specified ions as dopants in the
formulation. Further, it is to be understood that nanoparticles,
quantum dots, semiconductor particles, and other types of materials
can be used as wavelength converting materials. The list above is
representative and should not be taken to include all the materials
that may be utilized within embodiments described herein. A
wavelength converting material may include one or more of any of
the listed phosphors.
[0084] FIG. 13 is an exploded view of an LED lamp, according to
some embodiments. The exploded view illustrates an LED lamp 1300
with an MR-16 type design. As shown, a finned heat sink 1302 is
provided and one or more optical devices 150 (e.g., light source
142) can be positioned on the surface. Also shown in the exploded
view is a cover member 140, the cover member having a mixture of
wavelength converting materials distributed within the volume of
the cover member. An LED lamp 1300 can comprise an insertable
reflector 1304, and a protective lens 1301.
[0085] For embodiments powered by an external power source (e.g., a
power source from outside the lamp), a housing 1306 is provided. As
shown, the housing 1306 is configured to provide an electrical
connection to an external power source. Further, such a housing
comprises an interior void, suitable for containing electrical
components (e.g., a driver), possibly disposed on a printed circuit
board.
[0086] FIG. 14 is an illustration of an LED system 1400 comprising
an LED lamp 1410, according to some embodiments. The LED system
1400 is powered by an AC power source 1402, to provide power to a
rectifier module 1416 (e.g., a bridge rectifier) which in turn is
configured to provide a rectified output to an array of radiation
emitting devices (e.g., a first array of radiation emitting
devices, a second array of radiation emitting devices) comprising a
light source 142. A current monitor module 1405 is electrically
coupled to the first array and second array of radiation emitting
devices such that the current monitor module can determine a first
current level associated with the first array of radiation emitting
devices and a second current level associated with the second array
of radiation emitting devices; and a signal compensating module
1414 electrically coupled to the current monitor module 1405, the
signal compensating module being configured to generate a first
compensation factor signal based on a difference between the first
current level and a first reference current level. As shown, the
rectifier module 1416 and the signal compensating module (and other
components) are mounted to a printed circuit board 1403. Further,
and as shown, the printed circuit board 1403 is electrically
connected to a power pin 1415 mounted within a base member 151, and
the base is mechanically coupled to a heat sink 152. The heat sink
and base provide mechanical stability for an insertable reflector
1304.
[0087] FIG. 15 depicts a block diagram of a system to perform
certain functions to fabricate an optical device. As shown, FIG. 15
implements fabrication of an optical device, comprising one or more
steps for: preparing a submount having a surface (see module 1510);
disposing a first plurality of radiation sources configured to emit
radiation characterized by a first wavelength, the first wavelength
having a range of about 440 nm to about 500 nm, the first plurality
of radiation sources being positioned on the surface, the first
plurality of radiation sources having n number of radiation sources
(see module 1520); disposing a second plurality of radiation
sources configured to emit radiation characterized by a second
wavelength, the second wavelength being shorter than the first
wavelength, the second plurality of radiation source being
positioned on the surface, the second plurality of radiation
sources having m number of radiation sources, where a ratio between
m and n being predetermined based on a selected wavelength (see
module 1530); providing a first wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
second plurality of radiation sources, the first wavelength
converting layer having a wavelength emission ranging from about
590 nm to about 650 nm (see module 1540); providing a second
wavelength converting layer configured to absorb at least a portion
of radiation emitted by the second plurality of radiation sources,
the second wavelength converting layer having a wavelength emission
ranging from about 490 nm to about 590 nm (see module 1550).
[0088] In certain embodiments, an optical device comprises: a
submount having a surface; a first plurality of radiation sources
configured to emit radiation characterized by a first wavelength,
the first wavelength having a range of about 380 nm to about 470
nm, the first plurality of radiation sources being positioned on
the surface, the first plurality of radiation sources having n
number of radiation sources; a second plurality of radiation
sources configured to emit radiation characterized by a second
wavelength, the second wavelength being shorter than the first
wavelength, the second plurality of radiation source being
positioned on the surface, the second plurality of radiation
sources having m number of radiation sources, a ratio between m and
n being predetermined based on a selected wavelength; a first
wavelength converting layer configured to absorb at least a portion
of radiation emitted by the first plurality of radiation sources
and the second plurality of radiation sources, the first wavelength
converting layer having a wavelength emission ranging from about
590 nm to about 650 nm; a second wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
first plurality of radiation sources and the second plurality of
radiation sources, the second wavelength converting layer having a
wavelength emission ranging from about 490 nm to about 650 nm; and
a third wavelength converting layer configured to absorb at least a
portion of radiation emitted by the second plurality of radiation
sources, the third wavelength converting layer having a wavelength
emission ranging from about 440 nm to about 490 nm.
[0089] In certain embodiments of an optical device the first
plurality of radiation source is characterized by a peak emission
of about 420 nm to about 470 nm.
[0090] In certain embodiments of an optical device the second
plurality of radiation source is characterized by a peak emission
of about 380 nm to about 430 nm.
[0091] In certain embodiments, an optical device further comprises
encapsulating material overlaying the first plurality of radiation
sources, the encapsulating material comprising silicone and/or
epoxy material.
[0092] In certain embodiments of an optical device the first
plurality of radiation sources comprises a light emitting diode
(LED).
[0093] In certain embodiments of an optical device the ratio of the
number n to the number m (n:m) is greater than the ratio 1:2.
[0094] In certain embodiments of an optical device the total
emission color characteristic of the optical device is
substantially white color.
[0095] In certain embodiments of an optical device the ratio of the
number n to the number m (n:m) is about 1:1.
[0096] In certain embodiments, an optical device further comprises
a driving circuit configured to selectively power the first
plurality of radiation.
[0097] In certain embodiments, an optical device further comprises
driving circuit configured to tune to a ratio of energy being
delivered to the first plurality of radiation sources and energy
delivered to the second plurality of radiation sources.
[0098] In certain embodiments of an optical device the first
plurality of radiation sources and the second plurality of
radiation sources are arranged according to a predetermined
pattern.
[0099] In certain embodiments of an optical device, the optical
device comprises: a submount having a surface; a first plurality of
radiation sources configured to emit radiation characterized by a
first wavelength, the first wavelength having a range of about 380
nm to about 470 nm, the first plurality of radiation sources being
positioned on the surface, the first plurality of radiation sources
having n number of radiation sources; a second plurality of
radiation sources configured to emit radiation characterized by a
second wavelength, the second wavelength being shorter than the
first wavelength, the second plurality of radiation source being
positioned on the surface and arranged according to a predetermined
pattern, the second plurality of radiation sources having m number
of radiation sources, a ratio between m and n being predetermined
based on a selected wavelength; a first wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
first plurality of radiation sources and the second plurality of
radiation sources, the first wavelength converting layer having a
wavelength emission ranging from about 590 nm to about 650 nm; a
second wavelength converting layer configured to absorb at least a
portion of radiation emitted by the first plurality of radiation
sources and the second plurality of radiation sources, the second
wavelength converting layer having a wavelength emission ranging
from about 490 nm to about 590 nm; and a phosphor pattern
overlaying the second plurality of radiation sources, the phosphor
pattern being configured to absorb at least a portion of radiation
emitted by the second plurality of radiation sources, the phosphor
pattern being arranged according to the predetermined pattern, the
phosphor pattern having a wavelength emission ranging from about
440 nm to about 490 nm.
[0100] In certain embodiments of an optical device the second
plurality of radiation sources comprises LED devices.
[0101] In certain embodiments of an optical device the second
wavelength is less than 420 nm.
[0102] In certain embodiments of an optical device the first
wavelength converting layer is emits a red color.
[0103] In certain embodiments, an optical device further comprises
a housing.
[0104] In certain embodiments of an optical device the first
plurality of radiation sources are fabricated from gallium and
nitrogen containing material.
[0105] In certain embodiments of an optical device the first
plurality of radiation sources are fabricated from a bulk
submount.
[0106] In certain embodiments of an optical device the ratio of the
number n to the number m (n:m) is about 1:1.
[0107] In certain embodiments, an optical device further comprises
driving circuit configured to tune to a ratio of energy being
delivered to the first plurality of radiation sources and energy
delivered to the second plurality of radiation sources.
[0108] In certain embodiments of an optical device the first
plurality of radiation sources and the second plurality of
radiation sources are arranged according to a predetermined
pattern.
[0109] In certain embodiments of an optical device, the optical
device comprises: a submount having a surface; a first plurality of
radiation sources configured to emit radiation characterized by a
first wavelength, the first wavelength having a range of about 440
nm to about 500 nm, the first plurality of radiation sources being
positioned on the surface, the first plurality of radiation sources
having n number of radiation sources; a second plurality of
radiation sources configured to emit radiation characterized by a
second wavelength, the second wavelength being shorter than the
first wavelength, the second plurality of radiation source being
positioned on the surface, the second plurality of radiation
sources having m number of radiation sources, a ratio between m and
n being predetermined based on a selected wavelength; a first
wavelength converting layer configured to absorb at least a portion
of radiation emitted by the second plurality of radiation sources,
the first wavelength converting layer having a wavelength emission
ranging from about 590 nm to about 650 nm; and a second wavelength
converting layer configured to absorb at least a portion of
radiation emitted by the second plurality of radiation sources, the
second wavelength converting layer having a wavelength emission
ranging from about 490 nm to about 590 nm.
[0110] In certain embodiments of an optical device the first
plurality of radiation source is characterized by a peak emission
of about 480 nm to about 500 nm.
[0111] In certain embodiments of an optical device the second
plurality of radiation source is characterized by a peak emission
of about 380 nm to about 420 nm.
[0112] In certain embodiments of an optical device the first
plurality of radiation sources comprises a light emitting diode
(LED).
[0113] In certain embodiments of an optical device the ratio of the
number n to the number m (n:m) is greater than the ratio 22:2.
[0114] In certain embodiments of an optical device the ratio of the
number n to the number m (n:m) is about 10:1.
[0115] In certain embodiments of an optical device, the optical
device comprises driving circuit configured to tune to a ratio of
energy being delivered to the first plurality of radiation sources
and energy delivered to the second plurality of radiation
sources.
[0116] In certain embodiments of an optical device the first
plurality of radiation sources and the second plurality of
radiation sources are arranged according to a predetermined
pattern.
[0117] In certain embodiments of an optical device, the optical
device comprises: a submount having a surface; a first plurality of
radiation sources configured to emit radiation characterized by a
first wavelength, the first wavelength being greater than 590 nm,
the first plurality of radiation sources being positioned on the
surface, the first plurality of radiation sources having n number
of radiation sources; a second plurality of radiation sources
configured to emit radiation characterized by a second wavelength,
the second wavelength being shorter than 440 nm, the second
plurality of radiation source being positioned on the surface, the
second plurality of radiation sources having m number of radiation
sources, a ratio between m and n being predetermined based on a
selected wavelength; a first wavelength converting layer configured
to absorb at least a portion of radiation emitted by the second
plurality of radiation sources, the first wavelength converting
layer having a wavelength emission ranging from about 440 nm to
about 500 nm; and a second wavelength converting layer configured
to absorb at least a portion of radiation emitted by the second
plurality of radiation sources, the second wavelength converting
layer having a wavelength emission ranging from about 490 nm to
about 590 nm.
[0118] In certain embodiments of an optical device, the optical
device comprises: a submount having a surface; a first plurality of
radiation sources configured to emit radiation characterized by a
first wavelength, the first wavelength being greater than 590 nm,
the first plurality of radiation sources being positioned on the
surface, the first plurality of radiation sources having n number
of radiation sources; a second plurality of radiation sources
configured to emit radiation characterized by a second wavelength,
the second wavelength of about 440 nm to about 500 nm, the second
plurality of radiation source being positioned on the surface, the
second plurality of radiation sources having m number of radiation
sources, a ratio between m and n being predetermined based on a
selected wavelength; and a first wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
second plurality of radiation sources, the first wavelength
converting layer having a wavelength emission ranging from about
490 nm to about 590 nm.
[0119] In certain embodiments of an optical device, the optical
device comprises: a submount having a surface; a first plurality of
radiation sources configured to emit radiation characterized by a
first wavelength, the first wavelength being greater than 590 nm,
the first plurality of radiation sources being positioned on the
surface, the first plurality of radiation sources having n number
of radiation sources; a second plurality of radiation sources
configured to emit radiation characterized by a second wavelength,
the second wavelength of about 440 nm to about 500 nm, the second
plurality of radiation source being positioned on the surface, the
second plurality of radiation sources having m number of radiation
sources, a ratio between m and n being predetermined based on a
selected wavelength; and a first wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
second plurality of radiation sources, the first wavelength
converting layer having a wavelength emission ranging from about
490 nm to about 590 nm.
[0120] In certain embodiments, a lamp comprises: a base, the base
having at least one structural member to provide a mount point; and
an optical device, disposed on the mount point, the optical device
comprising: a first plurality of radiation sources configured to
emit radiation characterized by a first wavelength, the first
wavelength having a range of about 440 nm to about 500 nm, the
first plurality of radiation sources being positioned on the
surface, the first plurality of radiation sources having n number
of radiation sources a second plurality of radiation sources
configured to emit radiation characterized by a second wavelength,
the second wavelength being shorter than the first wavelength, the
second plurality of radiation source being positioned on the
surface, the second plurality of radiation sources having m number
of radiation sources, a ratio between m and n being predetermined
based on a selected wavelength; a first wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
second plurality of radiation sources, the first wavelength
converting layer having a wavelength emission ranging from about
590 nm to about 650 nm; and a second wavelength converting layer
configured to absorb at least a portion of radiation emitted by the
second plurality of radiation sources, the second wavelength
converting layer having a wavelength emission ranging from about
490 nm to about 590 nm.
[0121] In one or more preferred embodiments, various pattern and/or
arrangement for different radiation sources can be used. The above
description and illustrations should not be taken as limiting the
scope of the present disclosure, which is defined by the appended
claims.
* * * * *