U.S. patent application number 15/236898 was filed with the patent office on 2016-12-01 for small led source with high brightness and high efficiency.
The applicant listed for this patent is SORAA, INC.. Invention is credited to RAFAEL ALDAZ, AURELIEN J.F. DAVID, KEVIN HUANG, MICHAEL RAGAN KRAMES, FRANK M. STERANKA, TROY TROTTIER.
Application Number | 20160351761 15/236898 |
Document ID | / |
Family ID | 56610843 |
Filed Date | 2016-12-01 |
United States Patent
Application |
20160351761 |
Kind Code |
A1 |
DAVID; AURELIEN J.F. ; et
al. |
December 1, 2016 |
SMALL LED SOURCE WITH HIGH BRIGHTNESS AND HIGH EFFICIENCY
Abstract
Small LED sources with high brightness and high efficiency
apparatus including the small LED sources and methods of using the
small LED sources are disclosed.
Inventors: |
DAVID; AURELIEN J.F.; (SAN
FRANCISCO, CA) ; ALDAZ; RAFAEL; (PLEASANTON, CA)
; KRAMES; MICHAEL RAGAN; (MOUNTAIN VIEW, CA) ;
STERANKA; FRANK M.; (SAN JOSE, CA) ; HUANG;
KEVIN; (FREMONT, CA) ; TROTTIER; TROY; (SAN
JOSE, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SORAA, INC. |
FREMONT |
CA |
US |
|
|
Family ID: |
56610843 |
Appl. No.: |
15/236898 |
Filed: |
August 15, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14528818 |
Oct 30, 2014 |
9419189 |
|
|
15236898 |
|
|
|
|
61899723 |
Nov 4, 2013 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 33/46 20130101;
H01L 33/32 20130101; H01L 33/508 20130101 |
International
Class: |
H01L 33/50 20060101
H01L033/50; H01L 33/46 20060101 H01L033/46; H01L 33/32 20060101
H01L033/32 |
Claims
1. A light emitting diode (LED) device comprising: a submount; at
least one pump LED, grown on a substrate, wherein the LED comprises
a light-emitting active region comprising a base area; a
color-converting material overlying the at least one pump
light-emitting diode; and at least one flat emitting surface having
an emitting area and emitting substantially white light; wherein
the area of the at least one flat emitting surface is characterized
by an area less than 250 .mu.m.times.250 .mu.m, and a surface
brightness of 800 mW/mm.sup.2 or more; wherein the LED device is
characterized by a wall-plug efficiency of at least 25%.
2. The LED device of claim 1, wherein the substrate comprises a
bulk III-nitride-containing compound.
3. The LED device of claim 1, wherein the at least one pump LED is
configured to emit violet light.
4. The LED device of claim 1, wherein the at least one pump LED is
configured to emit blue light.
5. The LED device of claim 1, wherein the at least one flat
emitting surface emits light characterized by a CCT in a range from
about 2000K to about 10000K.
6. The LED device of claim 1, wherein the at least one LED is
configured to be driven at a current density in a range of about
100 A/cm.sup.2 to about 1000 A/cm.sup.2.
7. The LED device of claim 1, wherein light emitted by the LED
device exhibits a gamut of at least 70% of NTSC gamut.
8. The LED device of claim 1, wherein the at least one LED
comprises a flip-chip configuration.
9. The LED device of claim 1, wherein the base area is
characterized by a base shape that is substantially
rectilinear.
10. The LED device of claim 1, wherein the submount is
characterized by a reflectivity higher than 80% within at least a
wavelength in a range of 400 nm to 700 nm.
11. The LED device of claim 1, further comprising at least one
reflective material in proximity to at least one of the at least
one LED and in proximity to the color conversion material.
12. The LED device of claim 11, wherein the reflective material is
characterized by a reflectivity higher than 90% within at least a
wavelength in a range of 400 nm to 700 nm.
13. The LED device of claim 11, comprising an air gap between the
reflective material and at least one of the at least one LED and
the color conversion material.
14. The LED device of claim 13, wherein at least one of the
reflective material or the submount forms a diffuse reflector.
15. The LED device of claim 14, wherein at least one of the
reflective material or the submount comprises a metal material.
16. The LED device of claim 14, wherein at least one of the
reflective material or the submount comprises a dielectric
stack.
17. The LED device of claim 1, wherein a combined thickness of the
submount, the at least one LED, and the light-converting material
is less than 1 mm.
18. A light emitting diode (LED) device comprising a LED, wherein
the LED comprises: a base area less than 250 .mu.m.times.250 .mu.m;
and an emitting surface comprising an emitting area configured to
emit substantially white light; wherein the emitting surface is
characterized by a surface brightness of 800 mW/mm.sup.2 or more;
and wherein at least 80% of the base area is used for light
generation.
19. A light emitting diode (LED) device comprising: at least one
pump LED, wherein the at least one pump LED comprises: a base area;
a color-converting material overlying the at least one pump LED;
and at least one emitting surface configured to emit substantially
white light, wherein, the at least one emitting surface has an area
less than 250 .mu.m.times.250 .mu.m; is characterized by a surface
brightness of 800 mW/mm.sup.2 or more; and the at least one pump
LED is characterized by a wall-plug efficiency of at least 25%; and
a display component wherein the at least one pump light-emitting
diode is coupled to the display component.
20. The LED device of claim 19, wherein the display component
comprises a flat panel display.
Description
[0001] This application is a continuation of U.S. application Ser.
No. 14/528,818 filed on Oct. 30, 2014, which claims the benefit
under 35 U.S.C. .sctn.119(e) of U.S. Provisional Application No.
61/899,723, filed on Nov. 4, 2013, each of which is incorporated by
reference in its entirety.
FIELD
[0002] The disclosure relates to the field of LED-based
illumination products and more particularly to small LED sources
with high brightness and high efficiency and methods for using the
small LED sources.
BACKGROUND
[0003] The typical footprint of a high-brightness white LED is
around 1.times.1 mm.sup.2 (such as those used in automotive forward
lighting or camera flash applications); however, white LED sources
with a small footprint, high surface brightness, and high
efficiency are desirable for certain applications such as when they
are employed as light sources for displays. For example, high
brightness enables efficient coupling to display waveguides and
smaller optics or no optics. Likewise, a small footprint helps
reduce the size of the optics and the thickness of a display
system. It is also desirable that the LED's surface be flat rather
than dome-shaped, to improve system optical efficiency.
[0004] Contemporary literature has discussed how small sources
below 300 .mu.m.sup.2 can be desirable for display applications;
however, only monochromatic sources are proposed. White sources
require a color-conversion element for white-light generation,
which makes their miniaturization challenging.
[0005] Therefore, what is needed is an LED source that has a small
surface area, and emits a sufficient optical power from
substantially one surface with a sufficient efficiency.
[0006] This may be achieved in at least two ways: [0007] 1. Using a
low-droop device architecture which can be driven to a very high
current density while maintaining sufficient efficiency; and [0008]
2. Designing the electrode scheme such that a large enough fraction
of the footprint is used for light generation.
[0009] Embodiments of the disclosure may use either of these
approaches, or combine them. Below are described embodiments
following these approaches.
SUMMARY
[0010] Disclosed herein are methods and devices. One of the
disclosed devices comprises a light-emitting diode having a base
area less than 250 .mu.m.times.250 .mu.m; and an emitting surface
having an area configured to emit substantially white light. The
emitting surface is characterized by a surface brightness of 800
mW/mm.sup.2 or more and at least 80% of the base area is used for
light generation. In certain embodiments, a footprint of about 200
.mu.m.times.200 .mu.m is achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Those skilled in the art will understand that the drawings,
described herein, are for illustration purposes only. The drawings
are not intended to limit the scope of the present disclosure.
[0012] FIG. 1 shows a tradeoff curve illustrating problems to be
addressed when designing a small LED source with high brightness
and high efficiency.
[0013] FIG. 2A is a cross-section view of a wirebond LED for
discussing problems to be addressed when designing a small LED
source with high brightness and high efficiency.
[0014] FIG. 2B is a cross-section view of a flip-chip LED for
discussing problems to be addressed when designing a small LED
source with high brightness and high efficiency.
[0015] FIG. 3 shows a tradeoff curve of a blue-pumped thin-film
design for depicting performance characteristics to be considered
in the design of a small LED source with high brightness and high
efficiency.
[0016] FIG. 4 shows a tradeoff curve of a violet-pumped volumetric
LED for depicting performance characteristics to be considered in
the design of a small LED source with high brightness and high
efficiency.
[0017] FIG. 5 is a tradeoff curve of a violet-pumped volumetric LED
design for depicting how such LEDs maintain a high performance when
their footprint is scaled down for designing a small LED source
with high brightness and high efficiency.
[0018] FIG. 6A depicts an LED source placed on a high-reflectivity
submount as used in the design of a small LED source with high
brightness and high efficiency, according to some embodiments.
[0019] FIG. 6B depicts an LED source with a metal-like reflector as
used in the design of a small LED source with high brightness and
high efficiency, according to some embodiments.
[0020] FIG. 7 depicts an LED surrounded by a transparent layer as
used in designs for a small LED source with high brightness and
high efficiency, according to some embodiments.
[0021] FIG. 8 depicts an LED with an undersized color-conversion
layer as used in designs for a small LED source with high
brightness and high efficiency, according to some embodiments.
[0022] FIG. 9 depicts an LED with an oversized sized
color-conversion layer as used in designs for a small LED source
with high brightness and high efficiency, according to some
embodiments.
[0023] FIG. 10A1 and FIG. 10A2 depict an LED surrounded by
color-conversion materials as used in designs for a small LED
source with high brightness and high efficiency, according to some
embodiments.
[0024] FIG. 10B through FIG. 10F depict experimental results of
devices in accordance with some of the embodiments disclosed
herein.
[0025] FIG. 11 depicts an LED with light-blocking regions flanking
the LED as used in designs for a small LED source with high
brightness and high efficiency, according to some embodiments.
[0026] FIG. 12A depicts an LED with color-converting material
disposed in a cavity of a volumetric LED as used in designs for a
small LED source with high brightness and high efficiency,
according to some embodiments.
[0027] FIG. 12B depicts an LED with wavelength-selective reflector
as used in designs for a small LED source with high brightness and
high efficiency, according to some embodiments.
[0028] FIGS. 13A-13D depict LED cross-sections during a series of
fabrication steps where an LED is placed on the submount and a dam
material is placed around the small LED source with high brightness
and high efficiency, according to fabrication of some
embodiments.
[0029] FIGS. 14A-14D depict LED cross-sections during a series of
fabrication steps where an LED is placed on the submount and a thin
reflector is formed on the sides of the small LED source with high
brightness and high efficiency, according to fabrication of some
embodiments.
[0030] FIGS. 15A-15C depict LED cross-sections during a series of
fabrication steps where a color-conversion layer is placed on the
top of the small LED source with high brightness and high
efficiency, according to fabrication of some embodiments.
[0031] FIGS. 16A-16C depict LED cross-sections during a series of
fabrication steps where a color-conversion material is disposed to
surround the small LED source with high brightness and high
efficiency, according to fabrication of some embodiments.
[0032] FIG. 17 depicts an electrode scheme used with an LED having
a vertical chip geometry to form a small LED source with high
brightness and high efficiency, according to some embodiments.
[0033] FIG. 18 depicts an LED having a narrow n-grid that covers
part of the top surface of a small LED source with high brightness
and high efficiency, according to some embodiments.
[0034] FIG. 19 depicts a flip-chip LED having a narrow n-grid that
covers part of the top surface of a small LED source with high
brightness and high efficiency, according to some embodiments.
[0035] FIGS. 20A1-20I depict examples of uses for the disclosed
small LED source with high brightness and high efficiency,
according to some embodiments.
DETAILED DESCRIPTION
[0036] In many applications, it is desirable that an LED source
have a surface brightness of at least 800 mW/mm.sup.2. Assuming an
operating white-light wall-plug efficiency of about 20%, such an
LED should be driven at a power of about 160 mW and a current
density of about 130 A/cm.sup.2 to emit a sufficient amount of
light. What is needed is an LED source that has a small surface
area, and emits a sufficient optical power from substantially one
surface with a sufficient efficiency.
[0037] What follows are definitions, descriptions of materials used
in the embodiments, and a detailed discussion of the figures.
[0038] The term "exemplary" is used herein to mean serving as an
example, instance, or illustration. Any aspect or design described
herein as "exemplary" is not necessarily to be construed as
preferred or advantageous over other aspects or designs. Rather,
use of the word exemplary is intended to present concepts in a
concrete fashion.
[0039] The term "or" is intended to mean an inclusive "or" rather
than an exclusive "or". That is, unless specified otherwise, or is
clear from the context, "X employs A or B" is intended to mean any
of the natural inclusive permutations. That is, if X employs A, X
employs B, or X employs both A and B, then "X employs A or B" is
satisfied under any of the foregoing instances. In addition, the
articles "a" and "an" as used in this application and the appended
claims should generally be construed to mean "one or more" unless
specified otherwise or is clear from the context to be directed to
a singular form.
[0040] The term "logic" means any combination of software or
hardware that is used to implement all or part of the
disclosure.
[0041] The term "non-transitory computer readable medium" refers to
any medium that participates in providing instructions to a logic
processor.
[0042] A "module" includes any mix of any portions of computer
memory and any extent of circuitry including circuitry embodied as
a processor.
[0043] The term "area" describes the total area of an object and is
not tied to a specific shape. For example, and object of dimensions
100.times.100 .mu.m.sup.2 and an object of dimensions 10.times.1000
.mu.m.sup.2 have the same area, and can be characterized by "an
area of 100.times.100 .mu.m.sup.2". In other words, an object
having dimensions of 100.times.100 .mu.m.sup.2 includes an object
having an area of 10,000 .mu.m.sup.2. Furthermore, an object having
dimensions less than 100.times.100 .mu.m.sup.2 includes objects in
which one of the dimensions is less than 100 .mu.m and objects in
which both dimensions are less than 100 .mu.m such as, for example,
50.times.100 .mu.m.sup.2 and 50.times.50 .mu.m.sup.2. Also, an
object having dimensions less than 100.times.100 .mu.m.sup.2
includes objects having an area less than 10,000 .mu.m.sup.2 such
as, for example, 1,000 .mu.m.sup.2 and 100 .mu.m.sup.2. Similar
definitions apply to objects having dimensions greater than the
indicated dimensions. The areas may be square, rectangular,
trapezoidal, circular, oval, or any other suitable shape.
[0044] The compositions of phosphors or other wavelength-converting
materials referred to in the present disclosure comprise any uses
of or combinations of various wavelength-converting materials.
[0045] 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 or oxynitridosilicates 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 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:
[0046] (Ba,Sr,Ca,Mg).sub.5(PO.sub.4).sub.3(Cl,F,Br,OH):Eu.sup.2+,
Mn.sup.2+ [0047] (Ca,Sr,Ba).sub.3MgSi.sub.2O.sub.8:Eu.sup.2+,
Mn.sup.2+ [0048] (Ba,Sr,Ca)MgAl.sub.10O.sub.17:Eu.sup.2+, Mn.sup.2+
[0049] (Na,K,Rb,Cs).sub.2[(Si,Ge,Ti,Zr,Hf,Sn)F.sub.6]:Mn.sup.4+
[0050] (Mg,Ca,Zr,Ba,Zn) [(Si,Ge,Ti,Zr,Hf,Sn)F.sub.6]:Mn.sup.4+
[0051] (Mg,Ca,Sr,Ba,Zn).sub.2SiO.sub.4:Eu.sup.2+ [0052]
(Sr,Ca,Ba)(Al,Ga).sub.2S.sub.4:Eu.sup.2+ [0053]
(Ca,Sr)S:Eu.sup.2+,Ce.sup.3+ [0054]
(Y,Gd,Tb,La,Sm,Pr,Lu).sub.3(Sc,Al,Ga).sub.5O.sub.12:Ce.sup.3+ The
group: [0055]
Ca.sub.1-xAl.sub.x-xySi.sub.1-x+xyN.sub.2-x-xyC.sub.xy:A [0056]
Ca.sub.1-x-zNa.sub.zM(III).sub.x-xy-z
Si.sub.1-x+xy+zN.sub.2-x-xyC.sub.xy:A [0057]
M(II).sub.1-x-zM(I).sub.zM(III).sub.x-xy-zSi.sub.1-x+xy+zN.sub.2-x-xyC.su-
b.xy:A [0058]
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.xy O.sub.w-v/2H.sub.v:A [0059]
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/3CxyO.sub.wH.sub.v:A 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. [0060] LaAl(Si.sub.6-z
Al.sub.z)(N.sub.10-zOz):Ce.sup.3+ (wherein z=1) [0061]
(Mg,Ca,Sr,Ma)(Y,Sc,Gd,Tb,La,Lu).sub.2S.sub.4:Ce.sup.3+ [0062]
(Ba,Sr,Ca).sub.xxSi.sub.yN.sub.z:Eu.sup.2+ (where 2x+4y=3z) [0063]
(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) [0064] (Lu,Ca,Li,Mg,Y)
.alpha.-SiAlON doped with Eu.sup.2+ and/or Ce.sup.3+ [0065]
(Ca,Sr,Ba)SiO.sub.2N.sub.2:Eu.sup.2+,Ce.sup.3+ [0066]
Sr,Ca)AlSiN.sub.3:Eu.sup.2+ [0067] CaAlSi(ON).sub.3:Eu.sup.2+
[0068] (Y,La,Lu)Si.sub.3N.sub.5:Ce.sup.3+ [0069]
(La,Y,Lu).sub.3Si.sub.6N.sub.11:Ce.sup.3+
[0070] 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.
[0071] 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.
[0072] The limitations found within devices resulting from legacy
attempts present many opportunities for advancing the state of the
art. For example, legacy blue-pumped thin-film white LEDs with high
brightness have been demonstrated. Such 1 mm.times.1 mm chips at an
injection current of 1 A have a brightness of about 700 mW/mm.sup.2
and a wall plug efficiency (WPE) of about 23%. The brightness of
these LEDs can be increased by driving them at higher current
densities, however, this reduces the wall-plug efficiency. The
reduction in efficiency at high current density is due to several
effects, including at least droop in internal quantum efficiency,
additional heating, and higher electrical losses at high
current.
[0073] What is needed is an LED source that has a small surface
area, and emits a sufficient optical power from substantially one
surface with a sufficient efficiency. The appended figures and
discussion thereto show how to make and use such LED sources.
[0074] FIG. 1 shows a tradeoff curve 100 illustrating problems to
be addressed when designing a small light emitting diode (LED)
source with high brightness and high efficiency.
[0075] FIG. 1 illustrates this tradeoff between efficiency and
brightness. In FIG. 1, a state-of-the-art blue-pumped 1 mm.sup.2
white LED is considered. This is a thin-film LED grown on a
sapphire substrate. The LED is inserted into a system with a base
temperature of 80.degree. C. (representative of realistic display
systems). The projected performance at various current densities is
shown. At higher current density, brightness increases and WPE
decreases. It should also be noted that reliable continuous
operation of such LEDs on sapphire is usually restricted to 100
A/cm.sup.2 and below.
[0076] For the device of FIG. 1 operated at 1 A, the brightness and
WPE performance are sufficient for display applications, however,
the source size is too large. Upon shrinking the LED to a suitable
footprint, the performance is negatively impacted by several
effects, including:
[0077] A fixed part of the total LED footprint is used by the
n-contacts.
[0078] No light generation occurs in this area which is typically
100 .mu.m.times.100 .mu.m or larger.
[0079] When the total LED area is reduced, this inactive area
occupies a larger fraction of the total area. Therefore the active
area is reduced, leading to worse efficiency droop.
[0080] Thermal and electrical resistance scale roughly inversely
with the LED active area. Therefore, smaller devices have both
increased electrical power losses and higher operating
temperatures.
[0081] FIG. 2A shows a cross-section view of a wirebond LED 2A00
for discussing problems to be addressed when designing a small LED
source with high brightness and high efficiency. The LED device
shown in FIG. 2A includes LED 203, p-contact 202, submount 208, and
wirebond ball 204.
[0082] Issues related to the n-contact footprint are illustrated in
FIGS. 2A and 2B. In traditional LEDs (FIG. 2A), the n-electrode
occupies a minimum size of about 100 .mu.m.sup.2 and above. In the
case of vertical LEDs, the presence of an n-bond pad (e.g., see
wirebond ball 204) that is used for wirebonding blocks light
emitted from the active region of the LED. If one elects to emit
light below the n-pad, a large fraction of the light is lost;
therefore, light generation beneath the n-contact is often
prevented by the introduction of a current-blocking area. A
current-blocking area is an area where no current injection occurs
(e.g., current-blocking area 203), and therefore no light is
generated. This can, for example, be achieved by not forming a
p-contact in that area--the p-contact may be replaced with an
insulating dielectric layer.
[0083] FIG. 2B shows a cross-section view of a flip-chip LED 2B00
for discussing problems to be addressed when designing a small LED
source with high brightness and high efficiency. The LED device
shown in FIG. 2B includes submount 208, p-contact 202, and n-via
206, and shows a cross-section of LED devices in which the
n-contact area occupies at least 100 .mu.m.sup.2.
[0084] In the case of flip-chip LEDs current-blocking areas are
created by the presence of large n-vias that contact the n-type
material from the bottom of the LED. A potentially large fraction
of the p-contact can be lost to n-vias.
[0085] FIG. 3 shows a tradeoff curve 300 of a blue-pumped thin-film
design for depicting performance characteristics to be considered
in the design of a small LED source with high brightness and high
efficiency.
[0086] FIG. 3 quantifies the impact that the above issues have on
performance. FIG. 3 shows several LED footprints (e.g., 1
mm.times.1 mm 302, 150 .mu.m.times.150 .mu.m 304, 200
.mu.m.times.200 .mu.m 306, etc.). When the footprint is reduced
from 1 mm.times.1 mm to 200 .mu.m.times.200 .mu.m and 150
.mu.m.times.150 .mu.m, performance is significantly reduced.
[0087] These issues and limitations are fundamental: as the
footprint of a GaN-based LED becomes smaller, the loss of relative
active area increases droop, and the electrical and thermal
resistance also increase. This increased electrical and thermal
resistance leads to a reduction in performance. What is needed is
an LED source, which has a small surface area, and emits a
sufficient optical power from substantially one surface with a
sufficient efficiency. This may be achieved in various ways. As
examples: [0088] 1. Using a low-droop device architecture that can
be driven to a very high current density while maintaining
sufficient efficiency. [0089] 2. Designing the electrode scheme
such that a large enough fraction of the footprint is used for
light generation (e.g., light is not prevented from escaping by the
presence and juxtaposition of the electrode).
[0090] Embodiments of the disclosure may use either of these
approaches, or combine them. Below are described embodiments
following these approaches.
[0091] The low-droop approach employs LEDs with reduced efficiency
loss at high current density. This is possible, according to some
embodiments, through the use of violet-pump LEDs on a bulk
III-nitride substrate. These LEDs may be grown on a polar,
non-polar, or semi-polar plane, and may have any shape (e.g.,
having a base that is square, rectangular, polygonal or
rectilinear, or circular or oblong, etc.).
[0092] FIG. 4 shows a tradeoff curve 400 of a violet-pumped
volumetric LED for depicting performance characteristics to be
considered in the design of a small LED source with high brightness
and high efficiency. The numbers on the graph indicated the
corresponding current density (A/cm.sup.2).
[0093] FIG. 4 shows the performance of a violet-pumped volumetric
white LED 404 grown on a bulk GaN substrate, with a footprint of
250 .mu.m.times.250 .mu.m. The 1 mm.sup.2 blue-pumped thin film
white LED 402 device of FIG. 1 is also shown for comparison. At a
current density of 50 A/cm.sup.2, the two devices have similar
performance. However, at higher current density, the violet-pumped
white LED maintains higher performance over a wide range of current
density operation. This is due to its lower efficiency droop, and
also to its lower electrical resistance, which is attributable at
least in-part to the use of a bulk GaN substrate.
[0094] FIG. 5 shows a tradeoff curve 500 of a violet-pumped white
volumetric LED design for depicting how such LEDs maintain a high
performance when the footprint is scaled down for producing a small
LED source with high brightness and high efficiency.
[0095] FIG. 5 shows how such LEDs maintain a high performance when
their footprint is scaled down. As shown, performance is only
marginally affected over the range, due at least in part to the low
droop and low electrical resistance of the devices. In addition,
operation at high current density (200 A/cm.sup.2 and greater) is
reliable. Due to the presence of the bulk substrate, such LEDs are
usually thick (100 .mu.m to 200 .mu.m) and emit light from all
sides. In some cases, however, the LED may be thinner, for example,
50 .mu.m thick or 10 .mu.m thick, or thinner. In certain
applications, (e.g., for display applications), it is preferred to
use LEDs in a configuration such that white light is emitted only
from or substantially from one surface.
[0096] The performance of many LED configurations are shown in FIG.
5, in particular corresponding to a footprint are of 250
.mu.m.times.250 .mu.m 502, 200 .mu.m.times.200 .mu.m 504, 150
.mu.m.times.150 .mu.m 506.
[0097] Embodiments of the invention are not limited to these
footprints. For example, in some embodiments, the footprint is 10
.mu.m.times.10 .mu.m or 1 .mu.m.times.1 .mu.m.
[0098] FIG. 6A depicts an LED source 6A00 placed on a
high-reflectivity submount as used in the design of a small LED
source with high brightness and high efficiency.
[0099] As shown in the embodiment of FIG. 6A, the LED source is
placed on a high-reflectivity submount 208. The top surface
dimensions are 150 .mu.m.times.150 .mu.m. The sidewalls of the LED
are covered by a reflective material 604. The top surface of the
LED 606 is covered by a color-conversion material 602 such as a
phosphor, with surface dimensions similar to that of the LED. Light
is substantially emitted by the top surface of the color-conversion
material. The sidewall reflective material 604 may be a diffuse
reflector, such as a TiO.sub.2-based reflector, a metallic mirror,
a dichroic mirror, or a combination of these elements. In certain
embodiments, the reflective material and/or the submount comprises
a diffuse reflector, a metal material, a dielectric stack, or a
combination of any of the foregoing.
[0100] In some embodiments, the use of a high-reflectivity submount
can be advantageous to reduce optical loss and thus improve optical
performance. In some cases, the reflectivity is high at the
emission wavelength of the pump LED. In some cases, the
reflectivity is high in a large range of angles and wavelengths
(e.g. across the visible range) to reduce optical loss for
converted light. In some embodiments, for example, reflectivity is
higher than 80% (or higher than 90%, or higher than 95%) across the
visible range and at all incident angles of light.
[0101] FIG. 6B depicts an LED source 6B00 with a metal-like
reflector as used in the design of a small LED source with high
brightness and high efficiency.
[0102] In the embodiment of FIG. 6B, the LED source is covered on
its sides with a first reflective material (e.g., reflective
material 604) that is planar to the top of the LED. A second
reflector 607, such as a metal reflector, with a small aperture
filled with the color-conversion material 602 is then placed on top
of the LED. The second reflector serves as a light blocking
material and cavity for the color-conversion material.
[0103] FIG. 7 depicts an LED 700 surrounded by a transparent layer
as used in designs for a small LED source with high brightness and
high efficiency.
[0104] In such embodiments as depicted in FIG. 7, the LED is
surrounded by a transparent material 609 (e.g., as air or
silicone). In one such embodiment, the transparent material 609 is
located all around the LED. In another embodiment, the transparent
material is located only on the sides of the LED. In another
embodiment, the transparent material is located only on top of the
LED. The embodiment further comprises a reflective material 604 in
proximity to the LED and/or in proximity to the color conversion
material. In some embodiments, an aperture is formed in the
reflective material where the color conversion material is
located.
[0105] FIG. 8 depicts an LED 800 with an undersized
color-conversion layer as used in designs for a small LED source
with high brightness and high efficiency. The LED device shown in
FIG. 8 includes LED 606, submount 208, reflective material 604, and
undersized color-conversion material 602.
[0106] The use of such an undersized color-conversion layer may be
advantageous to further reduce the optical size of the white
light-emitting surface with respect to the surface of the pump LED,
thus increasing the brightness of the system.
[0107] FIG. 9 depicts an LED 900 with an oversized sized
color-conversion layer as used in designs for a small LED source
with high brightness and high efficiency. The LED device shown in
FIG. 9 includes LED 606, submount 208, reflective material 604, and
oversized color-conversion material 602.
[0108] The use of such an oversized color-conversion layer may be
advantageous to improve the conversion efficiency of the system, by
limiting the deleterious backscattering of light in the LED
die.
[0109] FIG. 10A1 depicts an LED 10A100 surrounded by
color-conversion material as used in designs for a small LED source
with high brightness and high efficiency. The LED device shown in
FIG. 10A1 includes LED 606, submount 208, reflective material 604
and color-conversion material 602.
[0110] In this embodiment, the color-conversion material is placed
in proximity to the LED and reflective material is placed in
proximity to the sides of the color-conversion material. This
configuration may be advantageous to improve the optical efficiency
of the system, by limiting the deleterious backscattering of light
in the LED die. Further, in this configuration the light
backscattered to the siders of the LED is more substantially
color-converted light (and less substantially direct pump light
from the LED). Such longer-wavelength converted light incurs lower
optical loss when backscattered in the die, thus improving optical
efficiency.
[0111] FIG. 10A2 depicts an LED 10A200 surrounded by
color-conversion material as used in designs for a small LED source
with high brightness and high efficiency. The LED device shown in
FIG. 10A2 includes LED 606, submount 208, reflective material 604,
color-conversion material 602, and air gap 10A210.
[0112] The embodiment shown in FIG. 10A2 is similar in some aspects
to that of FIG. 10A1, however, an air gap 10A210 is present
in-between the color conversion material and the reflective
material. The purpose of the air gap is to reduce the amount of
light escaping the color conversion material and reaching the
reflective material due to total internal reflection (TIR) at the
air gap interface. This can further improve device performance as
light undergoing TIR is reflected without any loss. In some
embodiments, the air gap has a width of 1 .mu.m, 10 .mu.m, 100
.mu.m. In other embodiments, the gap is formed by a low-index
substance other than air. For example, the color-conversion
material may be formed of phosphor particles in an encapsulant with
index n approximately equal to 1.4 or 1.5, and the low-index
substance has an index approximately equal to 1.2 or 1.3. The low
index may be obtained by a variety of means, for example by
dielectric materials or by pores such as air pores.
[0113] In addition to the selection of color-conversion materials
(e.g., as heretofore described) the selection of materials with
high reflectivity can be made in order to reduce the source size
while maintaining a high efficiency. The following section presents
experimental data illustrating this.
[0114] FIG. 10B shows the measured optical reflectivity spectrum of
two different diffuse reflectors at normal incidence from air. The
lower reflectivity material (reflector 2) has a reflectivity of
less than 94% for wavelengths >500 nm. The higher reflectivity
material (reflector 1) has a reflectivity of >97% for
wavelengths >500 nm. Such materials can be used in embodiments.
In some embodiments the reflectance is only slightly wavelength
dependent. For example, in some embodiments, the reflectance can
have a constant value within 1% or within 5% in the range from 400
nm to 700 nm. In some embodiments, the reflectance has a constant
value within 1% or within 5% in the range from 450 nm to 700 nm. In
some embodiments the reflectivity is higher than a given value (for
example 90% or 95% or 99%) at all angles of incidence from the
incoming medium (which may be air or an encapsulant).
[0115] The reflectivity of a high reflectivity material can be 96%,
97%, 98%, 99% or 100% depending on the material composition and
method of construction. These can pertain to the values coming from
air, or from an encapsulating medium (such as a silicone). In some
embodiments, white diffuse reflector materials can be made from
titanium oxide particles (rutile, anatase or brookite phase)
dispersed in a matrix of silicone or epoxy. The titanium oxide
particle sizes may range from 50 nm or smaller, 100 nm, 200 nm, 300
nm, 400 nm, 500 nm to 600 nm. In other embodiments, the diffused
white reflector can be composed of a network of polyethylene or
polytetrafluoroethylene particles or fibers with inter-penetrating
air pores or gaps. In some embodiments, the diffuse white reflector
comprises a material with air pores such as hollow silica spheres
embedded in an encapsulant. In some embodiments, dichroic specular
reflectors can be constructed from alternating layers of dielectric
material, which layers have different refractive indices. In some
embodiments, metallic specular reflectors can be made from smooth
film of silver metal that is more than 200 nm in thickness.
[0116] FIG. 10C shows the measured white wall plug efficiency (WPE)
of LED modules (CCT of 3000K, CRI of 80, current of 80 mA and
junction temperature of 85.degree. C.) with circular light emitting
areas of varying radii. The configuration of the LED modules is
shown in FIG. 10A. In some embodiments, the radius of the
light-emitting region can be 3 mm, 2 mm, 1 mm, 0.5 mm, 0.25 mm, 0.1
mm or smaller. As the radii of the emitting region is reduced from
2 mm to 0.35 mm, the wall plug efficiency decreases monotonically
due an increase of optical losses in the white reflector cup
surrounding the light-emitting region. The curves compare devices
built with a higher reflectivity cup (Reflector 1) and devices
built with a lower reflectivity cup (Reflector 2) as shown in FIG.
10B. For large radii (>1 mm), the effect of the reflectivity of
the cup is less pronounced, the WPE difference between Reflector 1
and Reflector 2 may be less than two percent. For small radii
(<0.5 mm), the reflectivity of the reflector material has a
large effect on the WPE of the device, which could differ by more
than five percent.
[0117] FIG. 10C illustrates results of using of materials with high
reflectivity (e.g., to maintain performance when the reflector
becomes close to the LED emitter). Some embodiments are further
reduced in footprint, and the use of high-reflectivity materials
becomes more dominant in such designs.
[0118] FIG. 10D shows the surface brightness (in W/mm.sup.2) of LED
modules (CCT of 3000K, CRI of 80, current of 80 mA and junction
temperature of 85.degree. C.) with circular light emitting areas of
varying radii. As the emitting area of the LED is decreased from a
circular source with 2 mm radius to one with 0.35 mm radius, the
surface brightness increases monotonically because the total light
emitted from the source is confined to a smaller area. The curves
compare devices built with a higher reflectivity cup (Reflector 1)
and devices built with a lower reflectivity cup (Reflector 2) as
shown on FIG. 10B. The surface brightness of LEDs packaged with
Reflector 1 increase more with decreasing emitting area compared to
LEDs packaged with Reflector 2, which is composed of a lower
reflectivity material. For a circular source radius of 0.35 mm,
LEDs made with reflector 1 exhibit 50% greater surface brightness
due to lower optical losses to the reflector cup.
[0119] In some applications that require high surface brightness
while maintaining reasonable white wall plug efficiency, the
reflectivity of the cup material can be selected, managed or
optimized. Given the same input current of 80 mA, the surface
brightness of the source can be increased by confining the light
emitting area to a smaller region, as shown in FIG. 10D. However,
this comes at the cost of decreasing white WPE (as shown in FIG.
10E) due to an increase of optical losses to the reflective cup.
For LEDs assembled with a lower reflectivity material (see
Reflector 2), the achievable surface brightness is severely limited
because the efficiency of the source drops sharply as the
light-emitting area is reduced. For LEDs assembled with a higher
reflectivity material (see Reflector 1), high surface brightness
can be achieved with a much lower penalty in white WPE. In the
example shown in FIG. 10E, the surface brightness of LEDs assembled
with Reflector 1 can be increased by more than 10 times while
incurring no more than 15% loss in white WPE.
[0120] FIG. 10F depicts WPE as a function of the height of the cup.
In addition to the aforementioned variables, the height of the cup
can also dramatically impact the overall white WPE of small LED
sources with less than 1 mm.sup.2 of emitting area. In some
embodiments, the thickness of the reflective cup can be 0.6 mm, 0.5
mm, 0.4 mm, 0.3 mm, 0.2 mm or 0.1 mm. As shown in FIG. 10F, for an
LED device (CCT of 3000K, CRI of 80, operating at 80 mA and
junction temperature of 85.degree. C.) with a 0.5 mm radius
circular light-emitting area, the white WPE of the source increases
as the thickness of the reflective cup is reduced (the phosphor
blend is tuned to maintain the same color point in each case).
Given the same emission area, when the white LED thickness
(determined by the cup height) is reduced, the proportion of light
that impinges upon the reflective cup also decreases, resulting in
less optical loss. For example, FIG. 10F shows that when the height
of the cup (Reflector 2) is reduced from 0.5 mm to 0.25 mm, the
white WPE is increased by more than 15%. This directly translates
into 15% higher surface brightness because the emitting area is
maintained.
[0121] In certain embodiments a combined thickness of the submount,
the at least one LED, and the light-converting material is less
than 2 mm, less than 1 mm, and in certain embodiments, less than
0.5 mm.
[0122] Other measures can be taken to reduce the loss in the
reflective material surrounding the LED. In some cases, an air gap
is created between the LED and the reflective material, or between
the color conversion material and the reflective material. In such
embodiments, the probability for light to reach the reflective
material is decreased. For example, if the color conversion
material surrounding the die has an index of about 1.4, only 50% of
the diffuse light in the color conversion material will escape to
the air gap and require reflection by the reflective material. The
air gap may, for example, have a thickness of about 1 .mu.m, 10
.mu.m, 100 .mu.m. FIG. 10A2 illustrates these embodiments.
[0123] Just as is the case for the reflective material, the
reflectivity of the submount is important to maintain performance.
In some embodiments, light bounces multiple times on the submount
before it escapes, so that the one-bounce loss from the submount is
amplified. Therefore, a high-reflectivity submount is desirable.
Such high-reflectivity mirrors can be composed of a metallic mirror
(such as silver) coated by a dielectric layer, or a series of
dielectric layers acting as a dichroic. In some embodiments, a
low-index layer is present in the stack of the submount to obtain a
total internal reflection (TIR) effect: large-angle light
undergoing TIR is perfectly reflected and does not travel to lossy
layers of the submount.
[0124] FIG. 11 depicts an LED 1100 with light-blocking regions
flanking the LED as used in designs for a small LED source with
high brightness and high efficiency. The LED device shown in FIG.
11 includes LED 606, submount 208, reflective material 604,
color-conversion material 602, and light-blocking material
1102.
[0125] In this embodiment, a light-blocking material 1102 is placed
above the active region of the LED 606 to prevent emission of light
that may diffuse through the reflective material 604. This
light-blocking material 1102 may, for example, be a metal, or a
substantially-black material.
[0126] The sidewalls of the LED need not be vertical. In some
embodiments, the sidewalls of an LED can be slanted with either a
positive or a negative angle from the vertical.
[0127] In some embodiments, the LED is thinned down so that only a
small fraction of the light can escape from the sides. For example,
the vertical-to-horizontal aspect ratio of the LED can be less than
10%. In some of these embodiments, no sidewall reflector is used.
In some embodiments, this thinning approach is combined with a
sidewall reflector such as one of the reflectors described in
previous embodiments.
[0128] FIG. 12A depicts an LED 12A00 with color-converting material
disposed in a cavity of a volumetric LED as used in designs for a
small LED source with high brightness and high efficiency. The LED
device shown in FIG. 12A includes LED 606, submount 208, reflective
material 604, color-conversion material 602, and light-blocking
material 1102.
[0129] In the embodiments of FIG. 12A, the volumetric nature of the
LED die can be used. A cavity is etched in the LED--for example, in
the bulk GaN substrate. The cavity can be etched by dry etching or
by chemical etching. This cavity is then filled with a
white-emitting color-conversion material. This enables a thin LED
device profile. The sidewalls of the LED may be coated with a
reflective material, and a light-blocking material may be used to
mask the bare outer edge of the LED.
[0130] FIG. 12B depicts an LED 12B00 with wavelength-selective
reflector 1204 as used in designs for a small LED source with high
brightness and high efficiency. The LED device shown in FIG. 12B
includes LED 606, submount 208, color-conversion material 602,
reflective material 604, dam 12B02, wavelength-selective reflector
1204 and metal cap 1206.
[0131] In certain embodiments of FIG. 12B, a wavelength-selective
reflector 1204 such as a dichroic mirror is incorporated to the
design. This mirror may reflect the direct emission from the LED
but transmit the converted light, thus decreasing or removing the
need for a color-conversion material layer on top of the LED chip.
Some embodiments include a metal cap 1206 that creates an aperture
through which the direct emissions from the LED can pass. This
metal cap can be used to shrink the emitting area, for applications
requiring a specific small emitting area.
[0132] Further, some embodiments include a dam element 12B02. The
dam can be used in some fabrication flows, for example: first the
dam is placed around the LED, and then the color-conversion
material is dispensed (i.e. in liquid of paste form) in the dam
around the LED, and cured to reach a solid phase.
[0133] FIGS. 13A-13D depict LED cross-sections during a series of
fabrication steps (e.g., see cross-section 13A00, see cross-section
13B00, see cross-section 13C00, see cross-section 13D00) where an
LED is placed on the submount and a dam material is placed around
the small LED source with high brightness and high efficiency. The
devices shown in FIGS. 13A-13D include LED 606, submount 208, dam
12B02, reflective material 604, color-conversion material 602, and
light-blocking material 1102.
[0134] In such a technique, the LED is placed on the submount and a
dam element 12B02 is placed around the LED. Part of the volume
between the dam and the LED is filled with a reflective material
604. Part of the volume around the LED is filled with
color-conversion material 602. A light-blocking layer 1102 is
formed above.
[0135] FIGS. 14A-14D depict LED cross-sections during a series of
fabrication steps (e.g., see cross-section 14A00, see cross-section
14B00, see cross-section 14C00, see cross-section 14D00) where an
LED is placed on the submount and a thin reflector is formed on the
sides of the small LED source with high brightness and high
efficiency. The devices shown in FIGS. 14A-14D include LED 606,
submount 208, reflective material 604, and color-conversion
material 602.
[0136] As depicted in FIGS. 14A-14D, the LED is placed on the
submount 208 and a thin reflector 604 (such as a metal) is formed
on the sides of the LED. The color-conversion material 602 is the
placed on top of the LED. In some cases (e.g., as shown in FIGS.
14B-14D) a thin reflector covers both the sides of the die and
color-conversion-material mesa to facilitate top-side only
emissions.
[0137] FIGS. 15A-15C depict LED cross-sections during a series of
fabrication steps (e.g., see cross-section 15A00, see cross-section
15B00, see cross-section 15C00, see cross-section 15D00) where a
color-conversion layer is placed on the top of the small LED source
with high brightness and high efficiency. The LED devices shown in
FIGS. 15A-15C include LED 606, color-conversion material 602, tape
1502, submount 208, and reflective material 604.
[0138] In another technique, the color-conversion layer is first
placed on the top of the LED--for example while the LED is on a
tape. The LED is then attached to the submount. Finally the
reflective material is formed around the LED.
[0139] FIGS. 16A-16C depict LED cross-sections during a series of
fabrication steps 16A00-16C00 where a color-conversion material is
disposed to surround the small LED source with high brightness and
high efficiency. The LED devices shown in FIGS. 16A-16C include LED
606, color-conversion material 602, tape 1502, submount 208, and
reflective material 604.
[0140] In another technique, the color-conversion layer is first
placed around LED (e.g., while the LED is on a tape). The LED is
then attached to the submount. The reflective material is formed
around the color-conversion material.
[0141] Some approaches use a modified electrode layout to enable
high brightness operation from a small footprint. As previously
discussed and shown as pertaining FIG. 2, in traditional LEDs, the
n-electrode occupies a minimum size of 100 .mu.m.times.100 .mu.m
and above. For a device footprint of 200 .mu.m.times.200 .mu.m,
only 75% of the device area is being used for light generation. In
some embodiments of the present disclosure, the device area is 200
.mu.m.times.200 .mu.m or less, and the light-generating area is at
least 80% of the device area.
[0142] In some embodiments, this is obtained using a vertical chip
geometry.
[0143] FIG. 17 depicts an electrode scheme used with an LED 1700
having a vertical chip geometry to form a small LED source with
high brightness and high efficiency.
[0144] As shown in FIG. 17, a narrow n-grid 1703 (for example, 5
.mu.m wide or 1 .mu.m wide) covers part of the top surface of the
LED. The electrode runs to the side of the LED along one of the
sidewalls 1704 that has been passivated, for example, by deposition
of a dielectric layer (see passivated sidewall 1704). An n-wirebond
ball 204 is placed away from the LED so that it does not contribute
to light occlusion or shadowing or a reduction of the light
generation area. The narrow n-grid has an area that is less than
20% of the footprint of the LED. Also shown in FIG. 17 is a
cross-section 1750 of the LED, showing the p-contact 1705 (where
light is generated) and a current-blocking area 1706 under the
n-contact 1702 to prevent light generation there.
[0145] FIG. 18 depicts an LED 1800 having a narrow n-grid that
covers part of the top surface of a small LED source with high
brightness and high efficiency.
[0146] In another embodiment, as shown in FIG. 18, the n-grid runs
to the side of the LED on a planarizing layer 1802 rather than on a
sidewall of the LED.
[0147] In some embodiments, the modified electrode layout is
obtained in a flip-chip technology.
[0148] FIG. 19 depicts a flip-chip LED 1900 having a narrow n-grid
that covers part of the top surface of a small LED source with high
brightness and high efficiency. The device shown in FIG. 19
includes p-contact 202, n-contact 1702, and dielectric 1902.
[0149] In one such embodiment (as shown in FIG. 19), the n-contact
area is a small fraction of the light-emitting area. The submount
contains several layers which reconfigure the n and p electrodes,
increasing the area of the n-electrode under the LED for
interconnect purposes. Dielectric layers (e.g., dielectric 1902)
are employed to isolate the p and n electrodes. The two p-contact
parts of the LED are connected laterally out of the plane of the
figure.
[0150] As shown in FIGS. 17 and 18, the n-electrode may have a
cross shape or another shape in order to improve current spreading
in the LED.
[0151] Any of the schemes shown or referenced in FIGS. 18 and 19
use the same area of n-contact and light-generation blocking layers
near the active layer, however, flip-chip embodiments often
features a guard band around the n-contact that operate to decrease
the usable area for light emission. On the other hand, the
flip-chip configuration is more-compatible with certain fabrication
techniques, which can be used to create small emitting
surfaces.
[0152] The examples herein describe in detail examples of
constituent elements of the herein-disclosed embodiments. It will
be apparent to those skilled in the art that many modifications,
both to materials and methods, may be practiced without departing
from the scope of the disclosure.
[0153] Embodiments of the herein-disclosed LEDs can be used in
various lamps and in various applications. Such lamps and
applications can include automotive forward lighting or camera
flash applications. The aforementioned automotive forward lighting
or camera flash applications are merely some embodiments. Other
lamps can include lamps that conform to fit with any one or more of
a set of mechanical and electrical standards. Table 1 gives
standards (see "Designation") and corresponding
characteristics.
TABLE-US-00001 TABLE 1 Desig- Base Diameter IEC 60061-1 nation
(Crest of thread) Name standard sheet E5 5 mm Lilliput Edison Screw
7004-25 (LES) E10 10 mm Miniature Edison Screw 7004-22 (MES) E11 11
mm Mini-Candelabra Edison (7004-6-1) Screw (mini-can) E12 12 mm
Candelabra Edison Screw 7004-28 (CES) E14 14 mm Small Edison Screw
(SES) 7004-23 E17 17 mm Intermediate Edison 7004-26 Screw (IES) E26
26 mm [Medium] (one-inch) 7004-21A-2 Edison Screw (ES or MES) E27
27 mm [Medium] Edison Screw 7004-21 (ES) E29 29 mm [Admedium]
Edison Screw (ES) E39 39 mm Single-contact (Mogul) 7004-24-A1 Giant
Edison Screw (GES) E40 40 mm (Mogul) Giant Edison 7004-24 Screw
(GES)
[0154] Additionally, the base member of a lamp can be of any form
factor configured to support electrical connections, which
electrical connections can conform to any of a set of types or
standards. For example, Table 2 gives standards (see "Type") and
corresponding characteristics, including mechanical spacing between
a first pin (e.g., a power pin) and a second pin (e.g., a ground
pin).
TABLE-US-00002 TABLE 2 Pin center Pin Type Standard to center
diameter Usage G4 IEC 60061-1 4.0 mm 0.65-0.75 mm MR11 and
(7004-72) other small halogens of 5/10/20 watt and 6/12 volt GU4
IEC 60061-1 4.0 mm 0.95-1.05 mm (7004-108) GY4 IEC 60061-1 4.0 mm
0.65-0.75 mm (7004-72A) GZ4 IEC 60061-1 4.0 mm 0.95-1.05 mm
(7004-64) G5 IEC 60061-1 5 mm T4 and T5 (7004-52-5) fluores- cent
tubes G5.3 IEC 60061-1 5.33 mm 1.47-1.65 mm (7004-73) G5.3-4.8 IEC
60061-1 (7004-126-1) GU5.3 IEC 60061-1 5.33 mm 1.45-1.6 mm
(7004-109) GX5.3 IEC 60061-1 5.33 mm 1.45-1.6 mm MR16 and
(7004-73A) other small halogens of 20/35/50 watt and 12/24 volt
GY5.3 IEC 60061-1 5.33 mm (7004-73B) G6.35 IEC 60061-1 6.35 mm
0.95-1.05 mm (7004-59) GX6.35 IEC 60061-1 6.35 mm 0.95-1.05 mm
(7004-59) GY6.35 IEC 60061-1 6.35 mm 1.2-1.3 mm Halogen (7004-59)
100 W 120 V GZ6.35 IEC 60061-1 6.35 mm 0.95-1.05 mm (7004-59A) G8
8.0 mm Halogen 100 W 120 V GY8.6 8.6 mm Halogen 100 W 120 V G9 IEC
60061-1 9.0 mm Halogen (7004-129) 120 V (US)/ 230 V(EU) G9.5 9.5 mm
3.10-3.25 mm Common for theatre use, several variants GU10 10 mm
Twist-lock 120/230- volt MR16 halogen lighting of 35/50 watt, since
mid- 2000s G12 12.0 mm 2.35 mm Used in theatre and single-end metal
halide lamps G13 12.7 mm T8 and T12 fluorescent tubes G23 23 mm 2
mm GU24 24 mm Twist-lock for self- ballasted compact fluores-
cents, since 2000s G38 38 mm Mostly used for high- wattage theatre
lamps GX53 53 mm Twist-lock for puck- shaped under- cabinet compact
fluores- cents, since 2000s
[0155] The list in Table 2 is representative and should not be
taken to include all the standards or form factors that may be
utilized within embodiments described herein.
[0156] In some embodiments the present disclosure can be applied
toward directional lighting applications as depicted in FIG. 20A1
through FIG. 20I. In these embodiments, one or more light-emitting
diodes 20A10, as taught by this disclosure, can be mounted on a
submount or package to provide an electrical interconnection. The
submount or package can be a ceramic, oxide, nitride,
semiconductor, metal, or combination thereof, that include
electrical interconnection capability 20A20 for the various LEDs.
The submount or package can be mounted to a heatsink member 20B50
via a thermal interface. The LEDs can be configured to produce a
desired emission spectrum, either by mixing primary emission from
various LEDs, or by having the LEDs photo-excite wavelength
down-conversion materials such as phosphors, semiconductors, or
semiconductor nanoparticles ("quantum dots"), or a combination of
any of the foregoing. The total light emitting surface (LES) of the
LEDs and any down-conversion materials can form a light source
20A30. One or more light sources can be interconnected into an
array 20B20, which is in turn in electrical contact with connectors
20B10 and brought into an assembly 20B30. One or more lens elements
20B40 can be optically coupled to the light source. The lens design
and properties can be selected so that the desired directional beam
pattern for a lighting product is achieved for a given LES. The
directional lighting product may be an LED module, a retrofit lamp
20B70, or a lighting fixture 20C30. In the case of a retrofit lamp,
an electronic driver can be provided with a surrounding member
20B60, the driver to condition electrical power from an external
source to render it suitable for the LED light source. The driver
can be integrated into the retrofit lamp. In the case of a fixture,
an electronic driver is provided which conditions electrical power
from an external source to make it suitable for the LED light
source, with the driver either integrated into the fixture or
provided externally to the fixture. In the case of a module, an
electronic driver can be provided to condition electrical power
from an external source to render it suitable for the LED light
source, with the driver either integrated into the module or
provided externally to the module. Examples of suitable external
power sources include mains AC (e.g., 120 Vrms AC or 240 Vrms AC),
low-voltage AC (e.g., 12 VAC), and low-voltage DC (e.g., 12 VDC).
In the case of retrofit lamps, the entire lighting product may be
designed to fit standard form factors (e.g., ANSI form factors).
Examples of retrofit lamp products include LED-based MR16, PAR16,
PAR20, PAR30, PAR38, BR30, A19 and various other lamp types.
Examples of fixtures include replacements for halogen-based and
ceramic metal halide-based directional lighting fixtures.
[0157] In some embodiments, the present disclosure can be applied
to non-directional lighting applications. In these embodiments, one
or more light-emitting diodes (LEDs), as taught by the disclosure,
can be mounted on a submount or package to provide an electrical
interconnection. The submount or package can be, for example, a
ceramic, oxide, nitride, semiconductor, metal, or combination of
any of the foregoing, that includes electrical interconnection
capability for the various LEDs. The submount or package can be
mounted to a heatsink member via a thermal interface. The LEDs can
be configured to produce a desired emission spectrum, either by
mixing primary emissions from various LEDs, or by having the LEDs
photo-excite wavelength down-conversion materials such as
phosphors, semiconductors, or semiconductor nanoparticles ("quantum
dots"), or a combination thereof. The LEDs can be distributed to
provide a desired shape of the light source. For example, one
common shape is a linear light source for replacement of
conventional fluorescent linear tube lamps. One or more optical
elements can be coupled to the LEDs to provide a desired
non-directional light distribution. The non-directional lighting
product may be an LED module, a retrofit lamp, or a lighting
fixture. In the case of a retrofit lamp, an electronic driver can
be provided to condition electrical power from an external source
to render it suitable for the LED light source, with the driver
integrated into the retrofit lamp. In the case of a fixture, an
electronic driver is provided to condition electrical power from an
external source to render it suitable for the LED light source,
with the driver either integrated into the fixture or provided
externally to the fixture. In the case of a module, an electronic
driver can be provided to condition electrical power from an
external source to render it suitable for the LED light source,
with the driver either integrated into the module or provided
externally to the module. Examples of external power sources
include mains AC (e.g., 120 Vrms AC or 240 Vrms AC), low-voltage AC
(e.g., 12 VAC), and low-voltage DC (e.g., 12 VDC). In the case of
retrofit lamps, the entire lighting product may be designed to fit
standard form factors (e.g., ANSI form factors). Examples of
retrofit lamp products include LED-based replacements for various
linear, circular, or curved fluorescent lamps. An example of a
non-directional lighting product is shown in FIG. 20C. Such a
lighting fixture can include replacements for fluorescent-based
troffer luminaires. In this embodiment, LEDs are mechanically
secured into a package 20C10, and multiple packages are arranged
into a suitable shape such as linear array 20C20.
[0158] Some embodiments of the present disclosure can be applied to
backlighting for flat panel display applications. In these
embodiments, one or more light-emitting diodes (LEDs), as taught by
this disclosure, can be mounted on a submount or package to provide
an electrical interconnection. The submount or package can be a
ceramic, oxide, nitride, semiconductor, metal, or combination of
any of the foregoing that include electrical interconnection
capability for the various LEDs. The submount or package can be
mounted to a heatsink member via a thermal interface. The LEDs can
be configured to produce a desired emission spectrum, either by
mixing primary emission from various LEDs, or by having the LEDs
photo-excite wavelength down-conversion materials such as
phosphors, semiconductors, or semiconductor nanoparticles ("quantum
dots"), or a combination of any of the foregoing. The LEDs can be
distributed to provide a desired shape of the light source. One
common shape is a linear light source. The light source can be
optically coupled to a lightguide for the backlight. This can be
achieved by coupling at the edge of the lightguide (edge-lit), or
by coupling light from behind the lightguide (direct-lit). The
lightguide distributes light uniformly toward a controllable
display, such as a liquid crystal display (LCD) panel. The display
converts the LED light into desired images based on electrical
control of light transmission and its color. One way to control the
color is by use of filters (e.g., color filter substrate 20D40,
filter substrate 20D40). Alternatively, multiple LEDs may be used
and driven in pulsed mode to sequence the desired primary emission
colors (e.g., using a red LED 20D30, a green LED 20D10, and a blue
LED 20D20). Optional brightness-enhancing films may be included in
the backlight "stack". The brightness-enhancing films narrow the
flat panel display emission to increase brightness at the expense
of the observer viewing angle. An electronic driver can be provided
to condition electrical power from an external source to render it
suitable for the LED light source for backlighting, including any
color sequencing or brightness variation per LED location (e.g.,
one-dimensional or two-dimensional dimming). Examples of external
power sources include mains AC (e.g., 120 Vrms AC or 240 Vrms AC),
low-voltage AC (e.g., 12 VAC), and low-voltage DC (e.g., 12 VDC).
Examples of backlighting products are shown in FIG. 20D1, FIG.
20D2, FIG. 20E1 and FIG. 20E2.
[0159] Some embodiments of the present disclosure can be applied to
automotive forward lighting applications, as shown in FIG. 20F. In
these embodiments, one or more light-emitting diodes (LEDs) can be
mounted on a submount or on a rigid or semi-rigid package 20F10 to
provide an electrical interconnection. The submount or package can
be a ceramic, oxide, nitride, semiconductor, metal, or combination
thereof, that include electrical interconnection capability for the
various LEDs. The submount or package can be mounted to a heatsink
member via a thermal interface. The LEDs can be configured to
produce a desired emission spectrum, either by mixing primary
emission from various LEDs, or by having the LEDs photo-excite
wavelength down-conversion materials such as phosphors,
semiconductors, or semiconductor nanoparticles ("quantum dots"), or
a combination of any of the foregoing. The total light emitting
surface (LES) of the LEDs and any down-conversion materials form a
light source. One or more lens elements 20F20 can be optically
coupled to the light source. The lens design and properties can be
selected to produce a desired directional beam pattern for an
automotive forward lighting application 20F30 for a given LED. An
electronic driver can be provided to condition electrical power
from an external source to render it suitable for the LED light
source. Examples of external power sources for automotive
applications include low-voltage DC (e.g., 12 VDC). An LED light
source may perform a high-beam function, a low-beam function, a
side-beam function, or any combination thereof. An example of an
automotive forward lighting product is shown in FIG. 20F.
[0160] In some embodiments, the present disclosure can be applied
to digital imaging applications, such as illumination for
mobile-phone and digital still cameras. In these embodiments, one
or more light-emitting diodes (LEDs), as taught by the disclosure,
can be mounted on a submount or package to provide an electrical
interconnection. The submount or package can be, for example, a
ceramic, oxide, nitride, semiconductor, metal, or combination of
any of the foregoing, that include electrical interconnection
capability for the various LEDs. The submount or package can be
mounted to a circuit board member. The LEDs can be configured to
produce a desired emission spectrum, either by mixing primary
emission from various LEDs, or by having the LEDs photo-excite
wavelength down-conversion materials such as phosphors,
semiconductors, or semiconductor nanoparticles ("quantum dots"), or
a combination thereof. The total light emitting surface (LES) of
the LEDs and any down-conversion materials form a light source. One
or more lens elements can be optically coupled to the light source.
The lens design and properties can be selected so that the desired
directional beam pattern for an imaging application is achieved for
a given LES. An electronic driver can be provided to condition
electrical power from an external source to render it suitable for
the LED light source. Examples of suitable external power sources
for imaging applications include low-voltage DC (e.g., 5 VDC). An
LED light source may perform a high-beam function, low-beam
function, side-beam function, daytime-running-light, or any
combination thereof. An example of an imaging lighting product is
shown in FIG. 20G.
[0161] FIG. 20 is a diagram illustrating a smart phone architecture
20H00. As shown, the smart phone 20H06 includes a housing, display,
and interface device, which may include a button, microphone,
and/or touch screen. In certain embodiments, a phone has a high
resolution camera device, which can be used in various modes. An
example of a smart phone can be an iPhone from Apple Inc. of
Cupertino, Calif. Alternatively, a smart phone can be a Galaxy from
Samsung or others.
[0162] In an example, the smart phone may include one or more of
the following features (which are found in an iPhone 4 from Apple
Inc., although there can be variations), see www.apple.com: [0163]
GSM model: UMTS/HSDPA/HSUPA (850, 900, 1900, 2100 MHz); GSM/EDGE
(850, 900, 1800, 1900 MHz) [0164] CDMA model: CDMA EV-DO Rev. A
(800, 1900 MHz) [0165] 802.11b/g/n Wi-Fi (802.11n 2.4 GHz only)
[0166] Bluetooth 2.1+EDR wireless technology [0167] Assisted GPS
[0168] Digital compass [0169] Wi-Fi [0170] Cellular [0171] Retina
display [0172] 3.5-inch (diagonal) widescreen multi-touch display
[0173] 800:1 contrast ratio (typical) [0174] 500 cd/m2 max
brightness (typical) [0175] Fingerprint-resistant oleophobic
coating on front and back [0176] Support for display of multiple
languages and characters simultaneously [0177] 5-megapixel iSight
camera [0178] Video recording, HD (720p) up to 30 frames per second
with audio [0179] VGA-quality photos and video at up to 30 frames
per second with the front camera [0180] Tap to focus video or still
images [0181] LED flash [0182] Photo and video geotagging [0183]
Built-in rechargeable lithium-ion battery [0184] Charging via USB
to computer system or power adapter [0185] Talk time: Up to 7 hours
on 3G, up to 14 hours on 2G (GSM) [0186] Standby time: Up to 300
hours [0187] Internet use: Up to 6 hours on 3G, up to 10 hours on
Wi-Fi [0188] Video playback: Up to 10 hours [0189] Audio playback:
Up to 40 hours [0190] Frequency response: 20 Hz to 20,000 Hz [0191]
Audio formats supported: AAC (8 to 320 Kbps), protected AAC (from
iTunes Store), HE-AAC, MP3 (8 to 320 Kbps), MP3 VBR, audible
(formats 2, 3, 4, audible enhanced audio, AAX, and AAX+), Apple
lossless, AIFF, and WAV [0192] User-configurable maximum volume
limit [0193] Video out support at up to 720p with Apple digital AV
adapter or Apple VGA adapter; 576p and 480p with Apple component AV
cable; 576i and 480i with Apple composite AV cable (cables sold
separately) [0194] Video formats supported: H.264 video up to 720p,
30 frames per second, main profile Level 3.1 with AAC-LC audio up
to 160 Kbps, 48 kHz, stereo audio in .m4v, .mp4, and .mov file
formats; MPEG-4 video up to 2.5 Mbps, 640 by 480 pixels, 30 frames
per second, simple profile with AAC-LC audio up to 160 Kbps per
channel, 48 kHz, stereo audio in .m4v, .mp4, and .mov file formats;
motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames
per second, audio in ulaw, PCM stereo audio in .avi file format
[0195] Three-axis gyro [0196] Accelerometer [0197] Proximity sensor
[0198] Ambient light sensor
[0199] Embodiment of the present disclosure may be used with other
electronic devices. Examples of suitable electronic devices include
a portable electronic device, such as a media player, a cellular
phone, a personal data organizer, or the like. In such embodiments,
a portable electronic device may include a combination of the
functionalities of such devices. In addition, an electronic device
may allow a user to connect to and communicate through the Internet
or through other networks, such as local or wide area networks. For
example, a portable electronic device may allow a user to access
the internet and to communicate using e-mail, text messaging,
instant messaging, or using other forms of electronic
communication. By way of example, the electronic device may be
similar to an iPod having a display screen or an iPhone available
from Apple Inc.
[0200] In certain embodiments, a device may be powered by one or
more rechargeable and/or replaceable batteries. Such embodiments
may be highly portable, allowing a user to carry the electronic
device while traveling, working, exercising, and so forth. In this
manner, and depending on the functionalities provided by the
electronic device, a user may listen to music, play games or video,
record video or take pictures, place and receive telephone calls,
communicate with others, control other devices (e.g., via remote
control and/or Bluetooth functionality), and so forth while moving
freely with the device. In addition, the device may be sized such
that it fits relatively easily into a pocket or the hand of the
user. While certain embodiments of the present disclosure are
described with respect to portable electronic devices, it should be
noted that the presently disclosed techniques may be applicable to
a wide array of other, less portable, electronic devices and
systems that are configured to render graphical data, such as a
desktop computer.
[0201] FIG. 20I depicts an interconnection of components in an
electronic device 20I00. Examples of electronic devices include an
enclosure or housing, a display, user input structures, and
input/output connectors in addition to the aforementioned
interconnection of components. The enclosure may be formed from
plastic, metal, composite materials, or other suitable materials,
or any combination thereof. The enclosure may protect the interior
components of the electronic device from physical damage, and may
also shield the interior components from electromagnetic
interference (EMI).
[0202] The display may be a liquid crystal display (LCD), a light
emitting diode (LED) based display, an organic light emitting diode
(OLED) based display, or some other suitable display. In accordance
with certain embodiments of the present disclosure, the display may
display a user interface and various other images such as logos,
avatars, photos, album art, and the like. Additionally, in certain
embodiments, a display may include a touch screen through which a
user may interact with the user interface. The display may also
include various functions and/or system indicators to provide
feedback to a user such as power status, call status, memory
status, or the like. These indicators may be incorporated into the
user interface displayed on the display.
[0203] In certain embodiments, one or more of the user input
structures can be configured to control the device, such as by
controlling a mode of operation, an output level, an output type,
etc. For example, the user input structures may include a button to
turn the device on or off. Further, the user input structures may
allow a user to interact with the user interface on the display.
Embodiments of the portable electronic device may include any
number of user input structures, including buttons, switches, a
control pad, a scroll wheel, or any other suitable input
structures. The user input structures may work with the user
interface displayed on the device to control functions of the
device and/or any interfaces or devices connected to or used by the
device. For example, the user input structures may allow a user to
navigate a displayed user interface or to return such a displayed
user interface to a default or home screen.
[0204] Certain device may also include various input and output
ports to allow connection of additional devices. For example, a
port may be a headphone jack that provides for the connection of
headphones. Additionally, a port may have both input and output
capabilities to provide for connection of a headset (e.g., a
headphone and microphone combination). Embodiments of the present
disclosure may include any number of input and/or output ports,
such as headphone and headset jacks, universal serial bus (USB)
ports, IEEE-1394 ports, and AC and/or DC power connectors. Further,
a device may use the input and output ports to connect to and send
or receive data with any other device, such as other portable
electronic devices, personal computers, printers, or the like. For
example, in one embodiment, the device may connect to a personal
computer via an IEEE-1394 connection to send and receive data files
such as media files. Further details of the device can be found in
U.S. Pat. No. 8,294,730.
[0205] FIG. 20H is a system diagram with a smart phone according to
an embodiment of the present disclosure. A server 20H02 is in
electronic communication with a handheld electronic device 20H06
having functional components such as a processor 20H08, memory
20H10, graphics accelerator 20H12, accelerometer 20H14,
communications interface 20H11, compass 20H18, GPS 20H20, display
20H22, and an input device 20H24. Each device is not limited to the
illustrated components. The components may be hardware, software or
a combination of both.
[0206] In some examples, instructions can be input to the handheld
electronic device 20H06 through an input device 20H24 that
instructs the processor 20H08 to execute functions in an electronic
imaging application. One potential instruction can be to generate a
wireframe of a captured image of a portion of a human user. In that
case the processor 20H08 instructs the communications interface
20H11 to communicate with the server 20H02 and transfer a human
wireframe or image data. The data is transferred by the
communications interface 20H11 and either processed by the
processor 20H08 immediately after image capture or stored in memory
20H10 for later use, or both. The processor 20H08 also receives
information regarding the display's 20H22 attributes, and can
calculate the orientation of the device, e.g., using information
from an accelerometer 20H14 and/or other external data such as
compass headings from a compass 20H18, or GPS location from a GPS
chip 20H20, and the processor then uses the information to
determine an orientation in which to display the image depending
upon the example.
[0207] The captured image can be drawn by the processor 20H08, by a
graphics accelerator 20H12, or by a combination of the two. In some
embodiments, the processor can be the graphics accelerator 20H12.
The image can first be drawn in memory 20H10 or, if available, the
memory directly associated with the graphics accelerator 20H12. The
methods described herein can be implemented by the processor 20H08,
the graphics accelerator 20H12, or a combination of the two to
create the image and related wireframe. Once the image or wireframe
is drawn in memory, it can be displayed on the display 20H22.
[0208] FIG. 20I is a diagram of a smart phone system diagram
according to an embodiment of the present disclosure. Computer
system 20I00 is an example of computer hardware, software, and
firmware that can be used to implement the disclosures above.
System 20I00 includes a processor 20I26, which is representative of
any number of physically and/or logically distinct resources
capable of executing software, firmware, and hardware configured to
perform identified computations. Processor 20I26 communicates with
a chipset 20I28 that can control input to and output from processor
20I26. In this example, chipset 20I28 outputs information to
display 20I42 and can read and write information to non-volatile
storage 20I44, which can include magnetic media and solid state
media, for example. Chipset 20I28 also can read data from and write
data to RAM 20I46. A bridge 20I32 for interfacing with a variety of
user interface components can be provided for interfacing with
chipset 20I28. Such user interface components can include a
keyboard 20I34, a microphone 20I36, touch-detection-and-processing
circuitry 20I38, a pointing device such as a mouse 20I40, and so
on. In general, inputs to system 20I00 can come from any of a
variety of machine-generated and/or human-generated sources.
[0209] Chipset 20I28 also can interface with one or more data
network interfaces 20I30 that can have different physical
interfaces. Such data network interfaces 20I30 can include
interfaces for wired and wireless local area networks, for
broadband wireless networks, as well as personal area networks.
Some applications of the methods for generating and displaying and
using the GUI disclosed herein can include receiving data over a
physical interface 20I31 or be generated by the machine itself by a
processor 20I26 analyzing data stored in memory 20I10 or 20I46.
Further, the machine can receive inputs from a user via a devices
keyboard 20I34, microphone 20I36, touch device 20I38, and pointing
device 20I40 and execute appropriate functions, such as browsing
functions by interpreting these inputs using processor 20I26.
[0210] In embodiments where the invention is used in a display
system, specific color properties of the emitted light may be
desirable. For example, it may be desirable that the emitted light
have a large color gamut. One known way to measure color gamut in
display applications is by a comparison to the NTSC gamut. In some
embodiments, the gamut is 50%, 70%, 90% or 100% of the NTSC gamut.
In some embodiments, the gamut is less than 50%, less than 70%,
less than 90%, and in some embodiments, less than 100% of the NTSC
gamut.
[0211] Finally, it should be noted that there are alternative ways
of implementing the embodiments disclosed herein. Accordingly, the
present embodiments are to be considered as illustrative and not
restrictive, and the claims are not to be limited to the details
given herein, but may be modified within the scope and equivalents
thereof.
* * * * *
References