U.S. patent application number 14/198528 was filed with the patent office on 2014-07-03 for method of light dispersion and preferential scattering of certain wavelengths of light for light-emitting diodes and bulbs constructed therefrom.
This patent application is currently assigned to SWITCH BULB COMPANY, INC.. The applicant listed for this patent is SWITCH BULB COMPANY, INC.. Invention is credited to Carol LENK, Ronald J. LENK.
Application Number | 20140184058 14/198528 |
Document ID | / |
Family ID | 38668231 |
Filed Date | 2014-07-03 |
United States Patent
Application |
20140184058 |
Kind Code |
A1 |
LENK; Ronald J. ; et
al. |
July 3, 2014 |
METHOD OF LIGHT DISPERSION AND PREFERENTIAL SCATTERING OF CERTAIN
WAVELENGTHS OF LIGHT FOR LIGHT-EMITTING DIODES AND BULBS
CONSTRUCTED THEREFROM
Abstract
A light emitting diode (LED) bulb configured to scatter certain
wavelengths of light. The LED bulb includes a base having threads,
a bulb shell, at least one LED, and a plurality of particles
disposed within the bulb shell. The plurality of particles has a
first and second set of particles. The first set of particles is
configured to scatter short wavelength components of light emitted
from the at least one LED and has particles with an effective
diameter that is a fraction of the dominant wavelength of the light
emitted from the at least one LED. The second set of particles is
configured to scatter light emitted from the at least one LED, and
has particles with an effective diameter equal to or greater than
the dominant wavelength of the light emitted from the at least one
LED.
Inventors: |
LENK; Ronald J.; (Woodstock,
GA) ; LENK; Carol; (Woodstock, GA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SWITCH BULB COMPANY, INC. |
SAN JOSE |
CA |
US |
|
|
Assignee: |
SWITCH BULB COMPANY, INC.
San Jose
CA
|
Family ID: |
38668231 |
Appl. No.: |
14/198528 |
Filed: |
March 5, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14040446 |
Sep 27, 2013 |
8704442 |
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14198528 |
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|
13476986 |
May 21, 2012 |
8569949 |
|
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14040446 |
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12299088 |
Oct 30, 2008 |
8193702 |
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PCT/US2007/010467 |
Apr 27, 2007 |
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13476986 |
|
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60797118 |
May 2, 2006 |
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Current U.S.
Class: |
313/512 ;
445/23 |
Current CPC
Class: |
F21V 3/00 20130101; F21Y
2115/10 20160801; F21K 9/60 20160801; F21K 9/64 20160801; F21K 9/90
20130101; F21V 3/063 20180201; F21K 9/232 20160801 |
Class at
Publication: |
313/512 ;
445/23 |
International
Class: |
F21K 99/00 20060101
F21K099/00 |
Claims
1. A light emitting diode (LED) light bulb, comprising: a base; a
bulb shell at least partially enclosing an inner portion of the LED
bulb; at least one LED located in the inner portion of the LED
bulb, the at least one LED configured to emit light at a dominant
wavelength; and a plurality of particles disposed within the inner
portion of the LED bulb, the plurality of particles configured to
scatter light emitted from the at least one LED, wherein the
plurality of particles comprises: a first set of particles having
an effective diameter that is less than the dominant wavelength of
the light emitted from the at least one LED; and a second set of
particles intermixed with the first set of particles, wherein the
particles of the second set comprise a different material than the
particles of the first set and have an effective diameter equal to
or greater than the dominant wavelength of the light emitted from
the at least one LED.
2. The LED bulb of claim 1, wherein the first set of particles is
configured to scatter short wavelength components of the light
emitted from the at least one LED by Rayleigh scattering.
3. The LED bulb of claim 1, wherein the second set of particles is
configured to scatter the light emitted from the at least one LED
by Mie scattering.
4. The LED bulb of claim 1, wherein the bulb shell has a thickness
and at least a portion of the plurality of particles is dispersed
within the thickness of the bulb shell.
5. The LED bulb of claim 1, wherein the at least one LED is
configured to emit light having a wavelength of about 430
nanometers.
6. The LED bulb of claim wherein the first set of particles is
alumina particles.
7. The LED bulb of claim 1, wherein the second set of particles has
particles with an effective diameter of about 1.1 microns.
8. The LED bulb of claim 1, wherein the first set of particles has
particles with an effective diameter of about 80 nanometers.
9. The LED bulb of claim 1, wherein the plurality of particles
includes particles with at least one of the shapes selected from
the group consisting of spherical, approximately spherical,
disk-shaped, and rod-shaped, or any combination thereof.
10. The LED bulb of claim 1, wherein the second set of particles is
alumina trihydrate particles.
11. The LED bulb of claim 1, wherein the second set of particles
includes particles with an effective diameter of about 1.1
microns.
12. The LED bulb of claim 1, wherein the bulb shell contains a
phosphor.
13. The LED bulb of claim 1, further comprising optics configured
to disperse the light emitted from the at least one LED.
14. The LED bulb of claim 1, wherein the at least one LED is a blue
LED.
15. A method of making a light emitting diode (LED) bulb,
comprising: disposing at least one LED within an inner portion of
the LED bulb, wherein the inner portion of the LED bulb is at least
partially enclosed by a bulb shell, and disposing, within the inner
portion of the LED bulb, a plurality of particles configured to
scatter light emitted from the at least one LED, wherein said
plurality of particles comprises: a first set of particles having
an effective diameter that is less than a dominant wavelength of
the light emitted from the at least one LED; and a second set of
particles intermixed with the first set of particles, wherein the
particles of the second set comprise a different material than the
particles of the first set and have an effective diameter equal to
or greater than the dominant wavelength of the light emitted from
the at least one LED.
16. The method of making an LED bulb of claim 15, wherein the
second set of particles is alumina trihydrate particles.
17. The method of making an LED bulb of claim 15, wherein the
second set of particles has particles with an effective diameter of
about 1.1 microns.
18. The method of making an LED bulb of claim 15, wherein the one
or more LEDs are configured to emit light having a wavelength of
about 430 nanometers.
19. The method of making an LED bulb of claim 15, wherein the first
set of particles is alumina particles.
20. The method of making an LED bulb of claim 15, wherein the first
set of particles has particles with an effective diameter of about
80 nanometers.
21. The method of making an LED bulb of claim 15, wherein the bulb
shell contains a phosphor.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a Continuation of U.S. patent
application Ser. No. 12/299,088, with a filing date of Oct. 30,
2008, which is an application filed under 35 U.S.C. .sctn.371 and
claims priority to International Application Serial No.
PCT/US2007/010467, filed Apr. 27, 2007, which claims priority to
U.S. Patent Provisional Application No. 60/797,118 filed May 2,
2006 which is incorporated herein by this reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to light-emitting diodes
(LEDs), and to replacement of bulbs used for lighting by LED bulbs.
More particularly, it relates to the preferential scattering of
certain wavelengths of light and dispersion of the light generated
by the LEDs in order to permit the LEDs to more closely match the
color of incandescent bulbs, or to the preferential scattering of
certain wavelengths of light and dispersion of the light of the
LEDs used in the replacement bulbs to match the light color and
spatial pattern of the light of the bulb being replaced.
BACKGROUND OF THE INVENTION
[0003] An LED consists of a semi-conductor junction, which emits
light due to a current flowing through the junction. At first
sight, it would seem that LEDs should make an excellent replacement
for the traditional tungsten filament incandescent bulb. At equal
power, they give far more light output than do incandescent bulbs,
or, what is the same thing, they use much less power for equal
light; and their operational life is orders of magnitude larger,
namely, 10-100 thousand hours vs. 1-2 thousand hours.
[0004] However, LEDs, and bulbs constructed from them, suffer from
problems with color. "White" LEDs, which are typically used in
bulbs, are today made from one of two processes. In the more common
process, a blue-emitting LED is covered with a plastic cap, which,
along with other possible optical properties, is coated with a
phosphor that absorbs blue light and re-emits light at other
wavelengths. A major research effort on the part of LED
manufacturers is design of better phosphors, as phosphors presently
known give rather poor color rendition. Additionally, these
phosphors will saturate if over-driven with too much light, letting
blue through and giving the characteristic blue color of
over-driven white LEDs.
[0005] An additional problem with the phosphor process is that
quantum efficiency of absorption and re-emission is less than
unity, so that some of the light output of the LED is lost as heat,
reducing the luminous efficacy of the LED, and increasing its
thermal dissipation problems.
[0006] The other process for making a "white" LED today is the use
of three (or more) LEDs, typically red, blue and green (RGB), which
are placed in close enough proximity to each other to approximate a
single source of any desired color. The problem with this process
is that the different colors of LEDs age at different rates, so
that the actual color produced varies with age. One additional
method for getting a "white LED" is to use a colored cover over a
blue or other colored LED, such as that made by JKL Lamps.TM..
However, this involves significant loss of light.
[0007] LED bulbs have the same problems as do the LEDs they use,
and further suffer from problems with the fact the LEDs are point
sources. Attempts to do color adjustment by the bulb results in
further light intensity loss.
[0008] Furthermore, an LED bulb ought to have its light output
diffused, so that it has light coming out approximately uniformly
over its surface, as does an incandescent bulb, to some level of
approximation. In the past, LEDs have had diffusers added to their
shells or bodies to spread out the light from the LED. Another
method has been to roughen the surface of the LED package. Neither
of these methods accomplishes uniform light distribution for an LED
bulb, and may lower luminous efficiency. Methods of accomplishing
approximate angular uniformity may also involve partially
absorptive processes, further lowering luminous efficacy.
Additionally, RGB (red, green, blue) systems may have trouble
mixing their light together adequately at all angles.
[0009] This invention has the object of developing a means to
create light from LEDs and LED bulbs that are closer to
incandescent color than is presently available, with little or no
loss in light intensity.
SUMMARY OF THE INVENTION
[0010] In one embodiment of the present invention, at least one
shell that is normally used to hold a phosphor that converts the
blue light from an LED die to "white" light contains particles of a
size a fraction of the dominant wavelength of the LED light, which
particles Rayleigh scatter the light, causing preferential
scattering of the red. In another embodiment of the present
invention, the at least one shell has both the phosphor and the
Rayleigh scatterers.
[0011] A further object of this invention is developing a means to
create light from LED bulbs that is closer to incandescent color
than is available using presently available-methods, with little or
no loss in light intensity. In one embodiment of the present
invention, the bulb contains particles of a size a fraction of the
dominant wavelength of the LED light, which particles Rayleigh
scatter the light, causing preferential scattering of the red. In
another embodiment of the present invention, only the at least one
shell of the bulb has the Rayleigh scatterers.
[0012] A yet further object of this invention is developing a means
to disperse light approximately evenly over the surface of an LED
bulb, with little or no loss in light intensity. In one embodiment
of the present invention, the bulb contains particles with size one
to a few times larger than the dominant wavelength of the LED
light, or wavelengths of multiple LEDs in a color-mixing system,
which particles Mie scatter the light, causing dispersion of the
light approximately evenly over the surface of the bulb. In another
embodiment of the present invention, only the at least one shell of
the bulb has the Mie scatterers.
[0013] In accordance with another embodiment, the method comprises
emitting light from at least one LED; and dispersing the light from
the at least one LED by distributing a plurality of particles
having a size one to a few times larger than a dominant wavelength
of the light from the at least one LED or wavelengths of multiple
LEDs in a color-mixing system in at least one shell of the LED
bulb.
[0014] In accordance with a further embodiment, a method for
creating light in an LED bulb that is closer to incandescent color
than is available using presently available methods, the method
comprises: emitting light from at least one LED; and preferential
scattering of the red light from the at least one LED by dispersing
a plurality of particles having a size a fraction of a dominant
wavelength of the light from the at least one LED or wavelengths of
multiple LEDs in a color-mixing system in an outer shell of the LED
bulb.
[0015] In accordance with another embodiment, a method for
dispersing light in an LED bulb, the method comprises: emitting
light from at least one LED; and scattering the light from the at
least one LED by distributing a plurality of particles having a
size one to a few times larger than a dominant wavelength of the
light from the at least one LED or wavelengths of multiple LEDs in
a color-mixing system in an LED bulb.
[0016] In accordance with a further embodiment, a method for
preferentially scattering light in an LED bulb, the method
comprises emitting light from at least one LED; and scattering the
light from the at least one LED by distributing a plurality of
particles having a size one to a few times larger than a dominant
wavelength of the light from the at least one LED or wavelengths of
multiple LEDs in a color-mixing system in an LED bulb.
[0017] In accordance with another embodiment, an LED comprises an
LED die; a shell encapsulating or partially encapsulating the die
and having a plurality of particles dispersed therein, and wherein
the plurality of particles are such a size as to disperse and/or
preferentially scatter the wavelength of the light emitted from the
LED.
[0018] In accordance with a further embodiment, an LED bulb
comprises a bulb having at least one shell having a plurality of
particle dispersed therein or in the bulb; at least one LED inside
or optically coupled to said bulb; and wherein said plurality of
particles are of such a size as to disperse and/or preferentially
scatter the wavelength of the light emitted from the at least one
LED.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention. In the
drawings,
[0020] FIG. 1 is a cross-sectional view of light emitted from an
LED having Rayleigh scattering from sub-wavelength particles.
[0021] FIG. 2 is a cross-sectional view of light emitted from an
LED having Mie scattering from supra-wavelength particles.
[0022] FIG. 3 is a cross-sectional view of an LED bulb showing an
LED embedded in a bulb, and the bulb and its shell containing both
Rayleigh and Mie scatterers.
[0023] FIG. 4 is a cross-sectional view of an LED showing an LED
die embedded in plastic, and the plastic and its shell containing
both Rayleigh and Mie scatterers.
DETAILED DESCRIPTION
[0024] Reference will now be made in detail to the present
preferred embodiments of the invention, examples of which are
illustrated in the accompanying drawings. Wherever possible, the
same reference numbers are used in the drawings and the description
to refer to the same or like parts. According to the design
characteristics, a detailed description of each preferred
embodiment is given below.
[0025] FIG. 1 shows a cross-sectional view of light emitted from an
LED being Rayleigh scattered from sub-wavelength particles 20 in
accordance with a first embodiment. As shown in FIG. 1, typically
the incoming light 10 will include a plurality of wavelength
components, including a wavelength 50 based on the light-emitting
material used within the LED (not shown). For example, in a typical
LED emission spectrum, the wavelength 50 emitted from the LED
corresponding to the color blue will be approximately 430 nm. As
shown in FIG. 1, the incoming light 10 impinges on a dispersed set
or plurality of particles 20 with an effective diameter 60. The
effective diameter 60 is preferably a fraction of the dominant
wavelength 50, which creates the condition for Rayleigh scattering
of the incoming light 10. For example, the dispersed set of
particles 20 can be 80 nm alumina particles. It can be appreciated
that other suitable particles having an effective diameter 60,
which is a fraction of the wavelength 50 of the emitting light
source or LED and creates Rayleigh scattering can be used. It can
be appreciated that the particles need not be spherical, or even
approximately spherical, and that other shapes can be used such as
disk or rod-shaped particles. As shown in FIG. 1, the short
wavelength components 30 are scattered by the particles 20, while
the transmitted light 40 having long wavelength components are
substantially unaffected. The transmitted light 40 is thus enhanced
in the color red relative to the incoming light 10, without
significantly affecting light intensity.
[0026] FIG. 2 shows a cross-sectional view of light emitted from an
LED having Mie scattering from a plurality of supra-wavelength
particles 70 and an equal scattering of each of the wavelengths 80
according to a further embodiment. Typically the incoming light 10
will include a plurality of wavelength components, including a
wavelength 50 based on the light-emitting material used within the
LED (not shown). For example, in a typical LED emission spectrum,
the wavelength 50 emitted from the LED corresponding to the color
blue will be approximately 430 nm. As shown in FIG. 2, the incoming
light 10 impinges on a dispersed set or plurality of particles 70
having an effective diameter 90, wherein the effective diameter 90
is greater than a dominant wavelength 50 of light emitted from the
LED. The effective diameter 90 of the dispersed particles 70 are
preferably a size one to a few times larger than a dominant
wavelength 50 of the light emitting source. For example, for an LED
producing a blue light, the dispersed set of particles 70 can be
alumina trihydrate having a diameter of approximately 1.1 microns.
It can be appreciated that any suitable particles having an
effective diameter 90, which is greater than the dominant
wavelength 50 of the emitting light source or LED and creates Mie
scattering can be used. It can be appreciated that the particles
need not be spherical, or even approximately spherical, and that
other shapes can be used such as disk or rod-shaped particles. This
creates the condition for Mie scattering of the incoming light 10,
wherein each of the incoming wavelengths 50 are scattered into an
outgoing wavelength 80. The transmitted light or outgoing
wavelengths 80 are thus dispersed in directions relative to the
incoming light 10, without significantly affecting the light
intensity.
[0027] FIG. 3 shows a cross-sectional view of a Rayleigh and Mie
scattering system 100 having an LED bulb 10 with an LED 120
embedded in the bulb 110 in accordance with one embodiment. The
bulb 100 comprises an LED 120 embedded in an inner portion 130 of
the bulb 110 and having an outer surface or shell 140, and a base
150 having threads. The LED bulb 100 contains within it at least
one LED 120, which is emitting light. As shown in FIG. 3, the inner
portion 130 and the shell 140 of the bulb 110 containing a
dispersed set of particles 20, 70, to produce scattering of the
light produced from the LED 120 in accordance with both Rayleigh
and Mie scattering. The light emitted from the LED 120 may contain
several wavelengths, but is undesirably enhanced in the blue due to
limitations in current LED technology. In order to preferentially
scatter the light emitted from the LED 120, the bulb shell 140 and
the body or inner portion 130 of the bulb 110 contain both
dispersed set of particles 20, 70 having a wavelength corresponding
to both Rayleigh scattering 20 and Mie scattering 70. In the case
of a LED 120, which produces a blue light, the dispersed set of
particles 20, 70 produces light, which is more like an incandescent
than the light emitted from the LED 120, (i.e., does not appear to
be as blue) as well as being more dispersed than the light emission
angle from the LED 120 would otherwise permit. It can be
appreciated that the bulb 110 can have more than one shell 140, and
that one or more of the shells 140 or the inner portion 130 can
contain dispersed particles 20, 70, which produce Rayleigh and/or
Mie scattering.
[0028] FIG. 4 shows a cross-sectional view of an LED 200 showing
the LED die 220 embedded in a plastic material 230 in accordance
with another embodiment. The LED die 220 is embedded in a plastic
material 230 or inner portion 232 and includes a shell 240. The
plastic material 230 and the shell 240 each contain a plurality of
dispersed particles 20, 70 therein. The plurality of dispersed
particles 20, 70 each having an effective diameter to produce
Rayleigh and Mie scattering of the light produced by the LED 200.
As shown in FIG. 4, the LED 200 contains within it at least one LED
die 220, which is emitting a source of light having a defined set
of wavelengths. Typically, the LED die 200 and the corresponding
source of light will contain many wavelengths, but is undesirably
enhanced in the blue and ultraviolet due to limitations in current
technology. The LED shell 240 typically is coated with a phosphor
that converts some of the light to a lower frequency, making the
light color closer to incandescent, but still undesirably enhanced
in blue. In the LED 200, the shell 240 and the body of the LED 230
contain both dispersed particles 20, 70, each having an effective
diameter 60, 90 to produce Rayleigh and Mie scatterering of the
source of light. The result is that the light emitted from the LED
200 is both less blue and more incandescent than the light emitted
from the LED die 220, as well as being more dispersed than the
light emission angle from the LED die 220 would otherwise permit.
The addition of the dispersed particles 20, 70, can be in addition
to the phosphor and optics that may be normally added to the LED
200.
* * * * *