U.S. patent number RE41,685 [Application Number 11/788,399] was granted by the patent office on 2010-09-14 for light source with non-white and phosphor-based white led devices, and lcd assembly.
This patent grant is currently assigned to Honeywell International, Inc.. Invention is credited to Brian David Cull, Dennis Michael Davey, Alan Stuart Feldman.
United States Patent |
RE41,685 |
Feldman , et al. |
September 14, 2010 |
Light source with non-white and phosphor-based white LED devices,
and LCD assembly
Abstract
A light source incorporates .Iadd.phosphor-based white
.Iaddend.light emitting diodes (LEDs). The LEDs may be raised off
the floor of the optical cavity to permit light to be emitted from
the base of the LED. Additionally, a reflective protrusion may be
placed beneath the raised LED to aid in redirecting light forward.
The LEDs may be skewed in relation to adjacent LEDs to reduce
interference. Non-white LEDs may be incorporated into the light
source to permit for selective color tuning. Fluorescent lamps may
also be implemented in combination with the LEDs to form a hybrid
light source. .Iadd.The light source may be used as a backlight for
a liquid crystal display assembly..Iaddend.
Inventors: |
Feldman; Alan Stuart (Phoenix,
AZ), Cull; Brian David (Massillon, OH), Davey; Dennis
Michael (Glendale, AZ) |
Assignee: |
Honeywell International, Inc.
(Morristown, NJ)
|
Family
ID: |
23879002 |
Appl.
No.: |
11/788,399 |
Filed: |
April 19, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
09473301 |
Dec 28, 1999 |
06666567 |
Dec 23, 2003 |
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Current U.S.
Class: |
362/237; 349/70;
362/236; 362/249.02; 362/97.3; 349/69; 362/231 |
Current CPC
Class: |
G02F
1/133603 (20130101); H01L 25/13 (20130101); H01L
33/60 (20130101); H01L 33/486 (20130101); G02F
1/133608 (20130101); H01L 2924/0002 (20130101); H01L
2924/09701 (20130101); G02F 1/133604 (20130101); H01L
2924/0002 (20130101); H01L 2924/00 (20130101) |
Current International
Class: |
G09F
13/04 (20060101); F21V 9/00 (20060101); F21S
4/00 (20060101) |
Field of
Search: |
;362/97,228,230,231,237,249,800,240,236,249.02,97.3 ;349/69,70 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2004200183 |
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Feb 2004 |
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AU |
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1 234 140 |
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Aug 2005 |
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EP |
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09006260 |
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Jan 1997 |
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JP |
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2000208815 |
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Jul 2000 |
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JP |
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2002198573 |
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Jul 2002 |
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JP |
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2003179259 |
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Jun 2003 |
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JP |
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WO 01/36864 |
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May 2001 |
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WO |
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Primary Examiner: Negron; Ismael
Attorney, Agent or Firm: Alston & Bird LLP
Parent Case Text
.Iadd.Notice: More than one reissue application has been filed for
the reissue of U.S. Pat. No. 6,666,567. The reissue applications
are application Ser. No. 11/788,399 (the present application), Ser.
No. 11/788,398(filed concurrently herewith), and Ser. No.
11/316,597, all of which are divisional reissues of U.S. Pat. No.
6,666,567..Iaddend.
Claims
What is claimed is:
1. A light source, comprising: an optical cavity having a floor; at
least one light emitting diode (LED) having a top and a bottom
coupled to said floor such that said bottom of said at least one
light emitting diode is elevated above said floor of said optical
cavity; and a reflective protrusion located below said at least one
LED.
2. A light source comprising: an optical cavity having a floor; at
least one fluorescent lamp coupled to said optical cavity; and at
least two LEDs coupled to said optical cavity, wherein adjacent
said at least two LEDs are skewed at approximately 45.degree.
relative to one another.
3. A light source comprising: an optical cavity having a floor; at
least one fluorescent lamp coupled to said optical cavity; and at
least two LEDs coupled to said optical cavity, wherein adjacent
said at least two LEDs are perpendicular to one another.
4. A light source comprising: an optical cavity having a floor; at
least one fluorescent lamp coupled to said optical cavity; and at
least one LED coupled to said optical cavity, wherein said at least
one LED is coupled with said optical cavity such that said LED is
elevated from said floor of said optical cavity.
5. A light source according to claim 4 further comprising a
protrusion on said floor positioned beneath said elevated LED.
6. A light source comprising: an optical cavity having a floor; at
least two fluorescent lamps coupled to said optical cavity; and at
least one LED coupled to said optical cavity, wherein two of said
fluorescent lamps are located at opposing sides of said optical
cavity, and said LEDs are located at intervals around substantially
the perimeter of said optical cavity.
7. A method of manufacturing a light source comprising the steps
of: providing an optical cavity having a floor; mounting at least
one LED having a top and bottom in said optical cavity such that
said bottom of said LED is elevated above said floor of said
optical cavity; and providing a protrusion below said at least at
one LED.
8. A method of manufacturing a light source comprising the steps
of: providing an optical cavity having a floor; mounting at least
one LED having a top and bottom in said optical cavity such that
said bottom of said LED is elevated above said floor of said
optical cavity; and mounting at least one fluorescent lamp in said
optical cavity.
9. A light source comprising: an optical cavity having a floor; a
plurality of fluorescent lamps coupled to said optical cavity
substantially parallel to one other; and a plurality of LEDs
coupled to said optical cavity interspersed among said fluorescent
lamps, wherein said plurality of LEDs are coupled to said optical
cavity, said plurality of LEDs having tops and bottoms and being
coupled to said optical cavity such that said bottoms of said LEDs
are elevated above said floor.
.Iadd.10. A light source comprising: an optical cavity; a plurality
of first light-emitting diodes each of which is a phosphor
light-emitting diode that emits white light, each first
light-emitting diode comprising a diode encased in a
light-transmitting package; a plurality of second light-emitting
diodes each of which emits non-white light, each second
light-emitting diode comprising a diode encased in a
light-transmitting package; wherein the first and second
light-emitting diodes are arranged to emit light into the optical
cavity such that mixing of spectral outputs from the first and
second light-emitting diodes occurs in the optical
cavity..Iaddend.
.Iadd.11. A light source of claim 10, further comprising at least
one third light-emitting diode having a spectral output different
from those of the first and second light-emitting
diodes..Iaddend.
.Iadd.12. A light source of claim 11, wherein the spectral output
of the second light-emitting diodes is a red output..Iaddend.
.Iadd.13. A light source of claim 11, wherein the spectral output
of the third light-emitting diode is a green output..Iaddend.
.Iadd.14. A light source of claim 13, further comprising at least
one fourth light-emitting diode having a blue output..Iaddend.
.Iadd.15. A liquid crystal display assembly comprising: a backlight
including: an optical cavity; a plurality of first light-emitting
diodes each of which is a phosphor light-emitting diode that emits
white light, each first light-emitting diode comprising a diode
encased in a light-transmitting package; a plurality of second
light-emitting diodes each of which emits non-white light, each
second light-emitting diode comprising a diode encased in a
light-transmitting package; wherein spectral outputs of the first
and second light-emitting diodes are operative to tune a color
balance of the backlight; wherein the first and second
light-emitting diodes are arranged to emit light into the optical
cavity such that mixing of the spectral outputs from the first and
second light-emitting diodes occurs in the optical cavity; and a
liquid crystal display panel positioned adjacent to the backlight
so as to be illuminated by the backlight..Iaddend.
.Iadd.16. A liquid crystal display assembly of claim 15, further
comprising at least one filter that is configured to be used with
the liquid crystal display panel and the backlight..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention generally relates to lighting systems, and
more particularly, to light sources implementing light emitting
diodes (LEDs).
2. Background
Many industries and applications need backlighting to illuminate an
information source. In particular, transmissive liquid crystal
displays (LCDs) have become very popular in many electronic media.
LCDs are useful in applications such as, but not limited to,
displays in avionics, laptop computers, video cameras, and
automatic teller machine displays. However, many LCDs require
backlighting to illuminate the information being displayed.
Many systems perform the backlighting function in conventional
displays. For example, one way to backlight an information source
employs an array of conventional straight tubular fluorescent
lamps. While these conventional lamps are inexpensive and do not
require complex electronic controls, they are sometimes inadequate
for particular applications. For instance, in avionics
applications, the poor color quality of the phosphors and the short
lamp life of these conventional lamps, among other shortcomings,
limit their usefulness.
To avoid the various problems with conventional lamps, many
manufacturers employ customized lamps, such as tubular serpentine
lamps. Unlike conventional fluorescent lamp arrays, custom-made
serpentine lamps commonly provide good color characteristics, light
luminance uniformity, and long lamp life. These lamps are typically
hand made, and consequently, are comparatively costly. Moreover,
these lamps. are extremely fragile and difficult to install.
Therefore, while custom-made tubular serpentine lamps may meet
certain standards for the backlighting function, the high cost and
fragility associated with these lamps detract from the advantages
they offer.
A third alternative for backlighting information sources is flat
fluorescent lamps. An exemplary flat fluorescent lamp, described in
U.S. Pat. No. 5,343,116, issued Aug. 30, 1994, to Winsor, comprises
a substrate fritted to a transparent cover lid, forming an
enclosure. Diffuse channels are formed into the substrate in the
interior of the enclosure. Standard phosphors are added to the
interior of the enclosure which is further flushed with a material
for emitting energy, such as argon or mercury. Energy is emitted in
the form of visible light when an electric potential is introduced
to the lamp by two electrodes, with one electrode placed at each
end of the diffuse channel. Such lamps potentially offer greater
ruggedness and lower manufacturing costs than serpentine tubular
lamp alternatives. However, these lamps are still costly to
manufacture and are difficult to repair.
Yet another alternative for backlighting information sources
implements LEDs. The use of LEDs as light sources can be
advantageous for several reasons. LEDs have a long life, which
reduces the frequency for replacing non-functioning diodes.
Further, when it is time to replace an LED, replacement is easier
and more cost effective than when replacing a fluorescent light
source. Additionally, LEDs are mechanically robust, i.e., they can
typically withstand greater shocks and vibration than conventional
fluorescent lights. Referring now to FIGS. 1 and 2, a conventional
light source 100 incorporating LEDs comprises an optical cavity
102, multiple LEDs 104, a power source (not shown), and a diffuser
106 (FIG. 2). Optical cavity 102 has a floor 108 in the interior
portion of light source 100 and an exterior surface 110.
As shown in FIG. 2, in conventional LED light systems, the LEDs 104
are attached directly to the floor 108 of the optical cavity 102.
Referring to FIG. 3, LED 104 typically comprises a surface mount
device constructed by encasing a diode 300 near the center of a
small translucent rectangular block 302. Electrical contacts 304
and 306 at the ends of block 302 connect to the diode via a small
lead frame 308.
Conventional LED lighting systems, however, fail to perform
adequately for many backlighting applications, such as avionics, in
which strict display performance requirements restrict their use.
For example, LEDs typically use power less efficiently than
conventional fluorescent lamps to produce comparable light
intensity. Further, a conventional fluorescent lamp relies on
phosphors which have narrowly defined spectral emission peaks that
must be carefully controlled to provide repeatable color output.
Control of the phosphor mixture to produce production-quality lamps
requires significant investment of time and effort to maintain a
uniform mixture, produce an acceptable color point, and ensure
color purity based on phosphor chemistry. Moreover, in conventional
white LEDs, the spectral emission is dominated by the blue spectral
emission, and thus, the resulting "white" light is heavily shifted
toward the blue spectrum. This shift limits the usefulness of LED
light sources in backlighting applications.
SUMMARY OF THE INVENTION
A light source according to various aspects of the present
invention comprises LEDs raised above the floor of the optical
cavity. The raised LEDs may optionally have a protrusion under the
LED for assisting in redirecting light. In another embodiment,
adjacent LEDs may be skewed relative to one another to reduce
absorption and reflection among the LEDs. In a further embodiment,
non-white LEDs may be incorporated into the light source to permit
selective color tuning. In an alternative embodiment, a hybrid
light source may be created when fluorescent lamps are augmented
with LEDs. These LEDs, which may optionally be raised above the
floor of the optical cavity, may also optionally have a protrusion
beneath. the raised LED.
BRIEF DESCRIPTION OF THE DRAWINGS
The subject matter of the invention is particularly pointed out and
distinctly claimed in the concluding portion of the specification.
The invention, however, both as to organization and method of
operation, may best be understood by reference to the following
description taken in conjunction with the claims and the
accompanying drawings, in which like parts may be referred to by
like numerals:
FIG. 1 is plan view of a prior art light source incorporating LED
technology;
FIG. 2 is a side cross-sectional view of the light source of FIG.
1;
FIG. 3 is a perspective view of a conventional diode;
FIG. 4. is a perspective view of an elevated diode in accordance
with an exemplary embodiment of the present invention;
FIG. 5 is plan view of a light source implementing LEDs in
accordance with an exemplary embodiment of the present
invention;
FIG. 6 is a side cross-sectional view of the light source of FIG.
5;
FIG. 7 is a side cross-sectional view of the light source of FIG. 5
having protrusions beneath the raised LEDs in accordance with a
further embodiment of the present invention;
FIG. 8 is a plan view of a light source configuring LEDs in an
orthogonal arrangement in accordance with an exemplary embodiment
of the present invention;
FIG. 9 is a plan view of a light source configuring LEDs in an
oblique arrangement in accordance with an exemplary embodiment of
the present invention;
FIG. 10 is a plan view of a hybrid light source incorporating LEDs
and tubular fluorescent lamps in accordance with an exemplary
embodiment of the present invention;
FIG. 11 is a plan view of a hybrid light source incorporating LEDs
and U-shaped fluorescent lamps in accordance with an exemplary
embodiment of the present invention;
FIG. 12 is a plan view of a hybrid light source incorporating LEDs
and a serpentine fluorescent lamp in accordance with an exemplary
embodiment of the present invention; and
FIGS. 13-15 are plan views of further embodiments of hybrid light
source configurations in accordance with various aspects of the
present invention.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
The ensuing descriptions are preferred exemplary embodiments only,
and are not intended to limit the scope, applicability, or
configuration of the invention in any way. Rather, the ensuing
descriptions provide a convenient description for implementing
various exemplary embodiments of light sources according to various
aspects of the present invention, it being understood that various
changes may be made in the function and arrangement of elements
described in the preferred embodiments without departing from the
spirit and scope of the invention as set forth in the appended
claims.
Referring now to FIGS. 4-6, a light source 500 in accordance with
various aspects of the present invention implements an LED that is
not flush with floor of the optical cavity. Raising LEDs 504 above
the surface tends to capture rear-emitted light that is otherwise
absorbed or otherwise lost, enabling the light source to emit more
light without additional power. In the present embodiment, the
light source 500 comprises: a housing 501 having a floor 410 and an
exterior wall 503 forming an optical cavity 502; multiple LEDs 400;
and a power source (not shown). The light source may further
include a diffuser 516 (FIG. 6). Housing 501 may be constructed of
any suitable material according to the criteria of the application,
such as heat exposure, mechanical shock resistance, or cost. In the
present embodiment, the housing 501 comprises aluminum, steel,
glass, or ceramics, and defines the optical cavity 502. The optical
cavity comprises any cavity defined in the housing in which light
is to be dispersed. The floor 410 and or wall 503 may optionally be
coated with a reflective material, for example, Duraflect.TM.,
expanded polytetrafluoroethylene, or any diffuse white paint such
as a polyurethane paint. The floor 410 comprises any suitable base
or surface for supporting the LEDs 400 or other relevant
components.
The power source provides appropriate power supply and control to
operate the lamp. The power source may provide power in any
appropriate form, such as AC electrical current, and may control
the power in any suitable manner, for example in conjunction with a
voltage source with current limiting resistance, a constant current
source, or a pulse width modulated current source,
LED 400 may be any LED suitable for the application, such as a
phosphor-based white LED sold by Nichia Corp, Tokushima, Japan. The
color, type, configuration, performance, and other characteristics
may be selected according to any appropriate criteria. In the
present embodiment, LED 400 includes a diode 402 encased in a
translucent rectangular package 404. The LED 400 is raised by a
support system 405 such that the base of LED 400 is elevated above
the floor 410 of optical cavity 502. For example, the support
system 405 suitably comprises a pair of L-brackets 406 and 408
attached to either side of the LED 400 to support the LED 400 above
the floor 410. L-brackets 406 and 408 may be affixed to floor 410
according to any suitable technique, such as by an adhesive,
fastener or solder. Any support system 405 that raises the LED 400
above floor 410, for example, by using raised, a support matrix, or
the like, may be used to support the LED 400.
The support system 405 may further connect the LED 400 to the power
source. For example, in the present embodiment, the L-brackets 406
and 408 may be constructed of a suitable electrically conductive
material that supports the, LED above the surface of the floor 410,
such as copper or beryllium. A lead frame 412 electrically connects
the diode 402 with L-brackets 406 and 408. L-brackets 406 and 408
are suitably connected to a printed circuit board which is
connected to the power source, for example through control
electronics.
In configurations where LEDs 400 are raised above floor 410, as in
FIGS. 5 and 6, the light output of the light source may be further
accomplished by providing a reflective protrusion beneath the
raised LEDs 504, further optimizing the recapture of emitted light.
By placing the protrusions under the raised LEDs 504, a greater
amount of light may be redirected forward, causing a greater light
output without requiring a corresponding increase in power.
Referring to the exemplary embodiment of FIG. 7, light source 700
has an optical cavity 502 above which LEDs 504 are mounted,
suitably by L-brackets 512 and 514. Protrusions 518 are located
approximately below LEDs 504. Protrusions 518 may be prepared in
any suitable manner and shape, such as according to the desired
application. For example, protrusions 518 may be prepared by
stamping the floor 410 of the optical cavity 502 such that
protrusions 518 form in the surface of the floor 410.
Alternatively, protrusions 518 may be constructed by adding
materials onto floor 410, for example, by placing droplets of an
epoxy material onto floor 410 and then covering the surface of the
epoxy with a reflective material. Protrusions 518 suitably have an
approximately parabolic or semi-spherical shape that is convex
relative to the floor 410 of optical cavity 502. Further,
protrusions 518 may alternatively be shaped to direct in a
predetermined direction. This configuration may be useful in
applications having a narrow range of desired viewing angles for an
associated display.
In accordance with various aspects of the present invention, the
light emitted by the light source may be further enhanced by
arranging the LEDs in an array that reduces any absorptive or
reflective effects of adjacent LEDs. For example, referring to FIG.
8, in accordance with a further embodiment of the present
invention, a light source 800 has an optical cavity 802 with a
floor 804. The longitudinal axes of a first set of LEDs are
oriented in a first direction, such as horizontally 806, and those
of a second set of LEDs are oriented in a second direction, such as
vertically 808, such that they are perpendicular to one another.
This orthogonal arrangement of adjacent LEDs, due to the relative
placement of neighboring LEDs, tends to reduce the absorptive or
reflective effect that adjacent LEDs may have on each other,
permitting a greater light output without requiring an additional
power input. Further, any or all of the LEDs may be mounted either
directly onto floor 804, or alternatively, may be mounted above
floor 804 as described above. Additionally, protrusions, as
described above in accordance with FIG. 7, may be added to further
enhance the recapture of rear-emitted light. Therefore, by skewing
orientation of the LEDs relative to one another, the intensity of
the light provided by the light source tends to increase without
requiring a corresponding increase in power. Light output may be
further enhanced by raising the LEDs above the optical cavity
floor.
Several variations in the orientation of the LEDs may be
implemented to enhance light output. For example, referring now to
FIG. 9, in accordance with yet another embodiment of the present
invention, light source 900 has an optical cavity 902 with a floor
904. Three sets of LEDs are oriented in three different directions,
such as vertically 908 and at approximately 45.degree. from the
vertical 906, 910. Due to the relative placement of neighboring
LEDs, this oblique configuration also tends to reduce the
absorptive or reflective effects of adjacent LEDs, yielding
improved output without requiring additional power. Further, in
accordance with other aspects of the present invention, any or all
of the LEDs may be mounted either directly onto floor 904, or
alternatively, may be mounted above floor 904 as described above.
Additionally, protrusions, as described in accordance with FIG. 7,
may be added to further enhance the recapture of rear-emitted
light.
A light source according to various aspects of the invention may
further be configured to exhibit improved spectral characteristics.
In accordance with a further embodiment of the present invention,
non-white LEDs, preferably, red, green, and blue LEDs, and more
preferably red and green LEDs, may be incorporated into the light
source as described and constructed in FIGS. 4-15 to enable it to
have a tunable color output. Non-white LEDs, in particular red,
green and blue LEDs may be any commercially available non-white
LED.
The non-white LEDs may be configured in the light source in a
variety of manners, including, but not limited to, clustering the
different LED types together, and by laying down each color in
separate rows. Further, non-white LEDs may be randomly dispersed
throughout the light source with white LEDs, and may also be used
in combination with fluorescent lamps as described below. The
non-white LEDs may be mounted directly on the floor of the optical
cavity, or as described in detail above, or they may be elevated
above the optical cavity floor, and further, they may optionally be
elevated above reflective protrusions as described above.
By incorporating non-white LEDs, multiple-wavelength LED light
sources are introduced into a diffuse optical cavity to allow color
mixing, with the purpose of increasing the color saturation of an
LED-based backlight to increase its usefulness in lighting an LCD
panel. These emission spectra allow tuning of the color balance of
the backlight by actively driving the LEDs or selectively enhancing
particular colors to achieve a desired balance. This tunability
allows one LED backlight to be used with a wide variety of LCD
panels possessing different combinations of color filters. It also
allows active tuning of the color balance of an LED-based light
source across the color spectrum, limited only by the saturation of
the individual color elements comprising the backlight. To exploit
the advantages of both LEDs and fluorescent light sources, a hybrid
light source may incorporate both LEDs and fluorescent lights.
Referring to FIG. 10, in accordance with an exemplary embodiment
according to various aspects of the present invention, a light
source 1000 has an optical cavity 1002 containing alternating rows
of tubular fluorescent lamps and LEDs. An optional reflective
cavity 1028 may be added to the light source to further enhance
light output. In accordance with this exemplary embodiment, six
tubular fluorescent lamps 1004, 1006, 1008, 1010, 1012, and 1014
are arranged in a parallel configuration within the optical cavity
1002. The fluorescent lamps may be mounted in any suitable manner,
for example, by using a support to mount the fluorescent lamp in
optical cavity 1002. Fluorescent lamps 1004, 1006, 1008, 1010,
1012, and 1014 may be any commercially available tubular
fluorescent lamp. These lamps may be either hot cathode or cold
cathode lamps and may have a variety of shapes, including, but not
limited to, straight, U-shaped (e.g., as elements 1106, 1108, and
1110 are illustrated in the exemplary embodiment shown in FIG. 11),
and serpentine fluorescent lamps (e.g., as element 1206 is
illustrated in the exemplary embodiment shown in FIG. 12).
LEDs may be interspersed among the fluorescent lamps in a variety
of configurations in the hybrid light source. As seen in FIG. 10,
rows of LEDs 1018, 1020, 1022, 1024, and 1026 are alternated in
between the fluorescent lamps 1004, 1006, 1008, 1010, 1012, and
1014. LEDs may be white LEDs, non-white LEDs, or may be a mixture
of both white and non-white LEDs as described above. Further, the
LEDs may be mounted directly to the floor 1030 of the optical
cavity 1002, or may be mounted above the optical cavity 1002 as
shown in FIG. 4, and may further be mounted over reflective
protrusions as described above. Further, the LEDs may be mounted in
skewed directions relative to adjacent LEDs as described in FIGS. 8
and 9.
It should be appreciated that the present invention is not limited
to the configurations described above. For example, referring to
FIGS. 13-15, various alternative embodiments may include an
edge-lit configuration, i.e., light floods the cavity from the
sides and is randomly reflected. In the edge-lit configurations,
the LEDs suitably face into the cavity, and not toward the
view.
Referring now to FIGS. 13 and 14, these figures illustrate light
source embodiments having the illumination sources around the
perimeter of the lamp. In FIG. 13, light source 1300 has LED rows
1302 and 1304 on opposite sides 1312 and 1314 of optical cavity
1306. Fluorescent lamps 1308 and 1310 are also located on opposite
sides 1316 and 1318 of optical cavity 1308. In FIG. 14, light
source 1400 has LEDs 1402 around the perimeter of optical cavity
1404. Fluorescent lamps 1406 and 1408 are on opposite side 1410 and
1412 of optical cavity 1404 The LEDs 1302, 1304 and 1402 of FIGS.
13 and 14 may be in a variety of orientations, including skewed
relative to one another, raised from the optical cavity surface,
and having a protrusion under the elevated LED. Further, a variety
of LED color combinations may be implemented to permit selective
color tuning
Referring now to FIGS. 13 and 14, these figures illustrate light
source embodiments having the illumination sources around the
perimeter of the lamp. In FIG. 13, light source 1300 has LED rows
1302 and 1304 on opposite sides 1312 and 1314 of optical cavity
1306. Fluorescent lamps 1308 and 1310 are also located on opposite
sides 1316 and 1318 of optical cavity 1306. In FIG. 14, light
source 1400 has LEDs 1402 around the perimeter of optical cavity
1404. Fluorescent lamps 1406 and 1408 are on opposite side 1410 and
1412 of optical cavity 1404. The LEDs 1302, 1304 and 1402 of FIGS.
13 aid 14 may be in a variety of orientations, including skewed
relative to one another, raised from the optical cavity surface,
and having a protrusion under the elevated LED. Further, a variety
of LED color combinations may be implemented to permit selective
color tuning.
It should be appreciated that in all embodiments of the present
invention any number of LEDs and fluorescent lamps may be used
according to the particular application or design criteria of the
backlight or the display. As such, the drawing figures and the
present description are only meant to illustrate exemplary
embodiments in accordance with the present invention and are not
intended to limit the invention to the configurations illustrated
herein.
Thus, a light source incorporating LEDs and fluorescent lamps
according to various aspects of the present invention provides
several features and advantages, such as light output uniformity.
In addition, the above descriptions are preferred exemplary
embodiments only, and are not intended to be limiting in any way.
Various modifications, substitutions, and other applications of the
present embodiments may be made without departing from the spirit
and the scope of the invention as set forth in the appended
claims.
* * * * *