U.S. patent application number 11/672748 was filed with the patent office on 2007-05-31 for airfield edge-light utilizing a side-emitting light source.
Invention is credited to Eric Darwin, Alan Glenn Glassner, Glenn Morrow.
Application Number | 20070121329 11/672748 |
Document ID | / |
Family ID | 35996000 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070121329 |
Kind Code |
A1 |
Morrow; Glenn ; et
al. |
May 31, 2007 |
AIRFIELD EDGE-LIGHT UTILIZING A SIDE-EMITTING LIGHT SOURCE
Abstract
A runway, taxiway or obstruction lighting system having at least
one side emitting LED mounted on a base. A cover is optically
coupled to the side emitting LED to direct light at a desired angle
from a horizontal plane extending from the base. The cover is
manufactured to have the highest transmissivity when used with a
monochromatic LED light source. The color of the material is tuned
to the wavelength of the LED light source to obtain the maximum
light output. A heater circuit is included in the lighting system
wired in series with the side emitting LED. A constant current
source is employed to supply power to the side emitting LED and
heater circuit so that operation of the heater circuit does not
affect the intensity of the light from the side emitting LED.
Inventors: |
Morrow; Glenn; (Westerville,
OH) ; Darwin; Eric; (Columbus, OH) ; Glassner;
Alan Glenn; (Columbus, OH) |
Correspondence
Address: |
SIEMENS CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
170 WOOD AVENUE SOUTH
ISELIN
NJ
08830
US
|
Family ID: |
35996000 |
Appl. No.: |
11/672748 |
Filed: |
February 8, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10931192 |
Aug 31, 2004 |
7192155 |
|
|
11672748 |
Feb 8, 2007 |
|
|
|
Current U.S.
Class: |
362/218 ;
362/217.1; 362/311.02 |
Current CPC
Class: |
H05B 45/3574 20200101;
Y02B 20/30 20130101; B64F 1/20 20130101; B64D 2203/00 20130101;
F21S 8/081 20130101; F21V 29/90 20150115; F21V 29/74 20150115; F21Y
2115/10 20160801; H05B 45/395 20200101; F21W 2111/06 20130101; Y02B
20/00 20130101; F21V 5/02 20130101 |
Class at
Publication: |
362/311 |
International
Class: |
F21V 3/00 20060101
F21V003/00 |
Claims
1. A light emitting apparatus, comprising: a housing; a base
mounted inside the housing; a side emitting light emitting diode
mounted on the base; and a translucent cover mounted on the
housing, optically coupled to the side emitting light emitting
diode; wherein the shape of the cover is configured to direct the
light from the side emitting light emitting diode in a desired
pattern.
2. The apparatus of claim 1, wherein the color of the translucent
cover is matched to the wavelength of the side emitting light
emitting diode to provide maximum light output.
3. The apparatus of claim 1, wherein the cover has a convex surface
for dispersing light approximately 0 to 6 degrees from a horizontal
plane extending from the base.
4. The apparatus of claim 1, wherein the cover has a slope adapted
for dispersing light approximately 0 to 6 degrees from a horizontal
plane extending from the base.
5. The apparatus of claim 1, wherein the side emitting light
emitting diode has an output of at least 20 lumens.
6. The apparatus of claim 1, the apparatus is an obstruction light
system and the side emitting light emitting diode further comprises
three side emitting light emitting diodes.
7. The apparatus of claim 6, wherein the three side emitting light
emitting diodes are suitably mounted so that at least two of the
diodes are visible at any angle on a horizontal plane extending
from the base.
8. The apparatus of claim 7, wherein the three side emitting diodes
are suitably mounted to be equidistant from each other.
9. The apparatus of claim 1 wherein the base is a heat-sink.
10. The apparatus of claim 1 wherein the side-emitting light
emitting diode and cover are suitably adapted to emit light
approximately 0 to 6 degrees from a horizontal plane parallel with
the base.
11. The apparatus of claim 1, wherein light is dispersed from the
side-emitting light emitting diode in a 360-degree pattern.
12. The apparatus set forth in claim 1, further comprising an
extension connected to the housing for elevating the light assembly
above a mounting surface, whereby the light assembly and the
extension are in a substantially vertical alignment.
13. The apparatus set forth in claim 12, wherein the extension
includes a frangible portion that fractures according to
predetermined criterion.
14. The apparatus set forth in claim 1, further comprising the
housing being suitably adapted to be at least one of installed
directly in the ground, installed directly in pavement, and mounted
on top of a standard FAA light base and transformer housing
15. The apparatus set forth in claim 14, the slope of the top
surface of the light fixture which protrudes above finish grade, is
a maximum of about 20.degree. and top surface protruding no more
than approximately 0.25 inches above a top cover.
16. The apparatus set forth in claim 15, wherein the translucent
cover is clear and the side emitting light emitting diode emits a
blue light of at least 20 lumens.
17. A light emitting apparatus, comprising: a housing; a base
mounted inside the housing; a light source mounted on the base; and
a translucent cover mounted on the housing, optically coupled to
the side emitting light emitting diode, the shape of the cover is
configured to direct the light from the side emitting light
emitting diode in a desired pattern; wherein the color of the
translucent cover is matched to the wavelength of the side emitting
light emitting diode to provide maximum light output.
18. The apparatus set forth in claim 15, wherein the translucent
cover is blue and the side emitting light emitting diode emits a
blue light of at least 20 lumens.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/931,192 filed on Aug. 31, 2004.
[0002] The present system is related to U.S. patent application
Ser. No. 10/096,440 by Hansler et al. entitled "Elevated Airfield
Runway and Taxiway Edge-Lights utilizing Light Emitting Diodes"
filed on Mar. 12, 2002 and which claims priority from U.S.
Provisional Patent Application Ser. No. 60/278,766, filed on Mar.
26, 2001, the entirety of which is hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0003] This invention is related to airfield lighting (e.g. runway,
taxiway and obstruction), and more particularly, to a side-emitting
lighting system utilizing a side-emitting Light Emitting Diode
(LED).
[0004] Airport edge lighting has been in existence for many years
utilizing incandescent lighting technology. Conventional designs
that utilize incandescent lights have higher power requirements,
lower efficiency, and low lamp life which needs frequent, costly
relamping by maintenance professionals.
[0005] Some airfield-lighting manufacturers are using more
efficient devices such as LEDs where the LEDs are arranged in
multiple rings shining outward. Optics of some sort are then used
to concentrate the light in the vertical and horizontal directions
to meet Federal Aviation Administration (FAA) specifications.
[0006] Recently, implementations utilizing top emitting LEDs have
been introduced which require additional light directing components
as well as costly reflection and/or refraction techniques in order
to comply with current FAA specifications and predetermined
criterion.
[0007] What is needed is an airfield edge-lighting system that can
utilize as few as one LED in a more efficient manner more
efficiently while meeting the required FAA standards.
SUMMARY OF THE INVENTION
[0008] The present invention, in accord with an aspect disclosed
herein, comprises a runway, taxiway or obstruction lighting system.
The lighting system includes a housing and a light assembly in
communication with the housing. The light assembly includes a base
with a top surface and a bottom surface whereby the bottom surface
of the base is in communication with the housing, a side-emitting
light emitting diode positioned on the top surface of the base, and
a cover suitably capable of transmitting light, the cover disposed
around the side-emitting light emitting diode and in communication
with the housing.
[0009] An aspect of the present system includes an electrical
circuit for operatively controlling an intensity of the light
emitting diode in accordance with a predetermined criteria (e.g.
FAA requirements). The electrical circuit may also suitably allow
for retrofitting the present light assembly into an existing
incandescent lighting system.
[0010] In one embodiment, a single side-emitting light emitting
diode (LED) is provided and suitably adapted to emit light
according to a predetermined criterion. Additionally, the
side-emitting LED may be suitably adapted to emit light
approximately 0 to 6 degrees from a horizontal plane parallel with
a mounting surface. As well, the system may be configured such that
the light is dispersed from the side-emitting LED in a 360-degree
pattern.
[0011] An alternative embodiment of the present invention employs
multiple side emitting LED's to realize the higher photometric
requirements for obstruction lights.
[0012] Further embodiments include a base configured to function as
a heat-sink. Yet another embodiment has a heating element disposed
within the cover and in close communication with the light
assembly. The heating element may be configured with a thermostat
for controlling the heating element.
[0013] Other embodiments include a cover that is cylindrical in
shape. Also, the cover may be tinted or colored (e.g. blue for
taxiway edge lighting applications). Further, the cover may include
a lens for refracting light emitted from the LED in accordance with
a predetermined criterion.
[0014] Still more embodiments may include an extension connected to
the housing for elevating the light assembly above a mounting
surface, whereby the light assembly and the extension are in a
substantially vertical alignment. As well, the extension may
include a frangible portion that fractures according to
predetermined criterion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] For a more complete understanding of the present invention
and the advantages thereof, reference is now made to the following
description taken in conjunction with the accompanying drawings, in
which:
[0016] FIG. 1 illustrates an elevated edge-light system, according
to a disclosed embodiment;
[0017] FIG. 2 illustrates an elevated edge-light system, according
to an alternate disclosed embodiment; and
[0018] FIG. 3 is a detailed drawing of an elevated edge-light
system in accordance with an aspect of the present invention.
[0019] FIG. 4 is a perspective view of a elevated edge-light system
using a side emitting light with a heater in accordance with an
aspect of the present invention.
[0020] FIG. 5 illustrates an elevated edge-light system employing
three side emitting light sources in accordance with an aspect of
the present invention.
[0021] FIG. 6 illustrates an inset edge light system in accordance
to an aspect of the present invention.
[0022] FIG. 7 is a circuit diagram of a heater circuit in
accordance with an aspect of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The following includes examples of various embodiments
and/or forms of components that fall within the scope of the
present system that may be used for implementation. Of course, the
examples are not intended to be limiting and other embodiments may
be implemented without departing from the spirit and scope of the
invention.
[0024] The Federal Aviation Administration (FAA) standards provide
guidelines for the manufacture and implementation of airfield
edge-lighting systems. Specifically, the FAA standards provide
guidelines for the intensity and directional projection of light
used in airfield lighting applications. The content and guidelines
of the FAA specifications, including but not limited to Advisory
Circular (AC) 150/5345-43E dated Oct. 19, 1995 and Advisory
Circular 150/5345-46B dated Sep. 1, 1998 are hereby incorporated
into this specification by reference in its entirety.
[0025] The present innovation is generally directed toward an LED
lighting assembly. More specifically, one embodiment of the present
innovation is directed toward a lighting assembly utilizing a
side-emitting light source (e.g. side-emitting light emitting diode
(LED)) for use in airport and airfield edge and obstruction
lighting applications. For example, aspects of the present
invention include a lighting assembly utilizing a side-emitting
light source that is compliant with one or more of FAA
specifications for L-810 Obstruction Light (AC 150/5345-43E and the
FAA LED Engineering Brief document 2004), L-852T LED Taxiway Edge
Light (AC 150/5345-46B and FAA LED Engineering Brief document
2004), and L-851T LED Elevated Taxiway Edge Light (AC 150/5345-46B
and FAA "LED Engineering Brief document 2004").
[0026] The FAA standards stipulate that a taxiway edge lighting
apparatus must meet certain photometric criterion. For example, the
current FAA specification mandates that the light intensity
projected from the lighting element must be at least 2.0 candela (a
unit of luminous intensity) between 0 and 6 degrees from the
horizontal axis (the horizontal axis being perpendicular to the
longitudinal axis of a mounting rod), and a minimum of 0.2 candela
between the remaining angle of 6 and 90 degrees from the horizontal
axis.
[0027] One embodiment of the disclosed lighting system is in
accordance with the current FAA requirements for taxiway edge
lighting. It will be appreciated that the present system may be
suitably configured to accommodate alternate and/or future
predetermined criteria (e.g. intensity, angle of projection) and/or
specifications.
[0028] Referring now to FIG. 1, there is illustrated an elevated
edge-light system 100, according to a disclosed embodiment.
Generally, the system 100 comprises a light assembly 105 elevated
above the surface of the ground 110. The light system 100 includes
a light assembly 105, a housing 115 that may be secured at its base
to a support structure 120 (e.g., an aluminum pipe extension). As
shown, the support structure 120 may include a frangible portion
130 in accordance with a predetermined criterion.
[0029] As illustrated in FIG. 1, a source of power may be suitably
provided from power elements located inside a power box 125.
Additionally, circuitry 135 may be provided in order to enable the
operation of the present system 100 to comply with predetermined
criterion. In operation, the output of the electrical circuit
element 135 may be operatively configured to supply the required
power to light assembly 105. In operation, power from the output of
the electrical circuit 135 may be carried across one or more wires
(not shown) to light assembly 105 to illuminate a light source
140.
[0030] Although the disclosed embodiment of FIG. 1 illustrates the
power box 125 and circuitry 135 located within housing 115, a
skilled artisan will appreciate that the components may be disposed
in any location without departing from the operation and scope of
the present innovation. For example, the power box 125 and
circuitry 135 may be located in alternate locations such as within
support structure 120, remotely in-ground 110 or the like without
departing from the spirit and scope of the present innovation.
[0031] Preferably, light assembly 105 includes a single side
emitting LED 140 as a light source, a mounting base 145 to support
the side emitting LED 140 and a cover 150 for transmitting the
light from the side-emitting LED. To comply with FAA regulations,
the single side emitting LED 140 has a minimum light output of
approximately 20-30 lumens.
[0032] An advantage of using an LED as opposed to an incandescent
bulb is that an LED has a much longer life cycle. A typical LED has
a life of 56,000 hours when operated at high intensity, and 150,000
hours (the equivalent of 34 years when operated 12 hours a day)
when operated at medium intensity.
[0033] It will be appreciated that the mounting base 145 may be
suitably configured to function as a heat sink (e.g., 3/4 inch
aluminum) such that heat is transferred from the LED assembly 140
to the housing 115 and other attached structures to prolong the
operating life of the LED assembly 140.
[0034] It will be appreciated that the mounting base or heat sink
145 may be suitably attached to the housing 115 by conventional
means while utilizing a thermal grease or comparable material
between the mounting base 145 and the housing 115 to facilitate
heat transfer from the LED assembly 140 to the housing 115, and
also between the LED assembly 140 and the mounting base 145 for the
same purpose.
[0035] It will be appreciated that the single side-emitting diode
140 of the embodiment may be any side-emitting light source known
in the art. For example, a Luxeon.TM. Star or provided by Lumileds
Lighting, LLC, 370 West Trimble Road, San Jose, Calif., 95131 may
be utilized in accordance with the disclosed embodiments.
Preferably, the LED has a minimum light output of 20-30 lumens.
[0036] The side-emitting LED 140 may be suitably configured to emit
light in a 360 degree pattern. For example, the side emitting LED
140 may be suitably configured to emit light corresponding to an
angle A 0 to 6 degrees above a horizontal plane B perpendicular
with the optical axis C. It will be appreciated that the angle A
may be adjusted in accordance with any desired lighting effect. It
will be appreciated, that any desired beam pattern may be achieved
by utilizing any number of optical techniques. For example, optical
manipulating techniques such as depressions and/or apex angles may
disposed within the cover 150 in order to refract and/or reflect
the light to correspond to any desired beam pattern or
predetermined criterion or standard. As well, alternate
side-emitting light sources 140 may be configured to alter the beam
pattern in accordance with desired criterion. Additionally, in
accordance with a predetermined criterion, the light intensity from
6 degrees from horizontal to the optical axis C may be arranged to
be 0.2 candela.
[0037] Although the embodiment utilizes a glass cover 150, it will
be appreciated that other translucent materials capable of
transmitting light known in the art may be used without departing
from the present lighting system 100. For example, the cover 150
may be constructed of materials including, but not limited to,
plastic, composites or the like.
[0038] In accordance with an aspect of the present invention, cover
150 is manufactured to have the highest transmissivity when used
with a monochromatic LED light source. The color of the material
(e.g., glass) is tuned to the wavelength of the LED light source to
obtain the maximum light output. For example a blue cover and a LED
for a taxiway light, a red cover and red LED for an obstruction
light.
[0039] The support structure 120 may suitably secure to the
mounting base 115 to provide a stable support for the light
assembly 105 during harsh weather conditions or other conditions
impacting operation and/or orientation of the lighting system 100.
The support structure 120 may suitably elevate light assembly 105
above the surface of the ground 110 wherein the light assembly 105,
support structure 120, and power box 125 are in a substantially
vertical alignment. Although the embodiment shown is vertically
orientated, an artisan will appreciate that other alternate
configurations, such as a flush fixture, of the present system may
be utilized without departing from the scope of the present
system.
[0040] An adjustment means (not shown) may be provided at the
junction of the base of the housing 115 and the support structure
120 so that the longitudinal axis C (i.e., the optical axis) of the
light assembly 105 may be adjusted to be maintained in a
substantially vertical orientation. It will be appreciated that any
adjustment means known in the art may be used without departing
from the scope of the present lighting system 100.
[0041] As shown, the support structure 120 may suitably include a
frangible section 130 which may function as an easy breakaway of
the light assembly 105 and upper end of the support structure 120
if, for example, an aircraft, maintenance vehicle, or other forces
exert a predetermined pressure on the frangible section 130
sufficient to cause breaking thereof.
[0042] It will be appreciated that any breakaway technique known in
the art may be used to accomplish the frangible characteristics.
For example, the frangible section 130 may comprise a groove scored
into the support structure 120, which groove is designed with a
sufficient length, depth, and orientation in the support structure
120 to facilitate separation of the light assembly 105 and upper
end of the support structure 120 from the power box 125 at or near
the surface of the ground 110. For example, where a threaded pipe
extension is utilized as the support structure 120, the frangible
section 130 may be a groove scored into the pipe surface, which
pipe is a single piece of pipe extending from the light assembly
105 to the power box 125.
[0043] Alternatively, the frangible section 130 may also suitably
comprise a compressed powderized metal coupler (not shown) designed
to separate under predetermined stress parameters utilized in
accordance with the particular application. In any case, the
function of the frangible connection 130 may be suitably configured
to facilitate a breakaway function under stressed conditions to
protect the lighting system 100 and the aircraft or other vehicle
that may impact the lighting system 100 from damage.
[0044] The power box 125 may suitably and operatively couple power
from a power feed (not shown) extending, for example, through an
in-ground conduit (not shown) to one or more of the lighting
systems 100. In the embodiment, the power box 125 may suitably
include an electrical circuit element 135 configured to control the
photometric characteristics of the light source 140 in accordance
with a predetermined criteria (e.g. FAA standards).
[0045] Additionally, the electrical circuit element 135 may be
designed to enable the retrofit of lighting system 100 into a
conventional or standard incandescent lighting system. In other
words, circuitry 135 may be provided to enable a variety of light
sources 140 (e.g. side-emitting light emitting diode) to provide
light intensity in accordance with a predetermined criteria (e.g.
FAA specifications).
[0046] It will be appreciated that the support structure 120 to
elevate the light assembly 105 above the ground as illustrated is
optional. For example, the light assembly 105 may be suitably
operable such that the base 145 of the light assembly 105 may be
situated on or close to the ground surface 110. Alternatively, the
light assembly 105 can be positioned in the ground such that only
the cover 150 sufficiently protrudes to provide the required output
light in accordance with desired criterion.
[0047] Referring now to FIG. 2, there is illustrated a lighting
system 200 in accordance with an alternate embodiment. As shown,
lighting assembly 205 may optionally include a heating element 210
to provide heat to a light source chamber 215. As illustrated,
light source chamber 215 is the space formed around a light source
225 (e.g. LED) and defined by an inner wall of the cover 220 and
mounting base 230.
[0048] It will be appreciated that the heating element 210 may be
any component known in the art capable of heating the light source
chamber 215. In operation, the heating element 210 raises the
temperature of the light source chamber 215 in order to control the
weather effects on the cover 220. For example, by heating the light
source chamber 215, the higher temperature may suitably reduce
icing, fogging and snow accumulation on top surface of the cover
220. As earlier discussed with reference to FIG. 1, it will be
appreciated that the mounting base 230 may suitably function as a
heat sink, alone, or in conjunction with housing 235 in order to
protect the longevity of the light source 225.
[0049] Referring now to FIG. 3, there is are illustrated exploded
view drawings of an elevated edge-light system 300 in accordance
with an aspect of the present invention. The power supply and
electronic circuitry for system 300 are displayed within circle
304. A plug 318 is used to couple system 300 to an external
electric power source. Wires 328 conduct the power from plug 318 to
the electronic circuitry shown in circle 304.
[0050] FIG. 3B shows a mounting assembly 330 in accordance with an
aspect of the present invention. The mounting assembly comprises a
heat sink 306. At the top of the assembly 330 is a side emitting
LED 308. The bottom of assembly 332 is adapted to mount on top 332
of housing 302. Heating element 310 is mounted around mounting
assembly 330. Wires 320 and 322 are connected to wires 324 and 326
to provide power to heating element 310 and side emitting LED 308
respectively.
[0051] FIG. 3C shows a cutaway view of a cover 312 in accordance
with an aspect of the present invention. Cover 312 is suitably
adapted to mount on housing 302 and cover mounting assembly 330.
Cover 312 has a convex surface 314 that is used to disperse light
from side emitting LED 308 corresponding to a desired angle. For
example side-emitting LED 308 may be suitably configured to emit
light in a 360 degree pattern along a horizontal axis. Convex
surface 314 adjusts the light along the horizontal axis to achieve
a desired lighting effect. It will be appreciated, that any desired
beam pattern may be achieved by utilizing any number of optical
techniques. For example, optical manipulating techniques such as
depressions and/or apex angles may disposed within the cover 312 in
order to refract and/or reflect the light to correspond to any
desired beam pattern or predetermined criterion or standard. Cover
312, is comprises of a translucent material capable of transmitting
light. In accordance with an aspect of the present invention, cover
312 is manufactured to have the highest transmissivity when used
with a monochromatic LED light source. The color of the material
(e.g., glass) is tuned to the wavelength of side emitting LED light
308 to obtain the maximum light output. A second convex surface 316
adjusts light along the vertical axis.
[0052] FIG. 4 is a detailed view of a mounting unit 400 for a side
emitting light with a heater in accordance with an aspect of the
present invention. As shown, the mounting unit 400 has a heater
support insulator 402 mounted on top of heat sink 308. Insulating
paper 404 is between mounting unit 400 and heating element.
[0053] FIG. 5 illustrates an elevated edge-light system 500
employing three side emitting light sources in accordance with an
aspect of the present invention. The additional light sources can
provide additional light intensity such as is required under FAA
guidelines for obstruction lights.
[0054] FIG. 5A is a side view of the system 500 and FIG. 5B is a
cutaway top view of the system along lines A-A of FIG. 5A. System
500 comprises a housing 502 that contains an LED electronics module
504. LED electronics module 504 is used for supplying the power to
side emitting LED's 508, 510, 512. The power from the LED
electronics module 504 can be varied control the intensity of side
emitting LED's 508, 510, 512. The wavelength of LEDs 508, 510, 512
is selected to produce a desired output color. LED
mounting/heatsink sub assembly 506 is mounted on top of housing 502
and is used for mounting side emitting LED's 508, 510 and 512.
Cover 514, an airfield lighting dome, is mounted on top of housing
502 and help in place by screws 516. The color of cover 514 is
suitably adapted to match the wavelength of LEDs 508, 510 and 512.
Cover 514 has a convex surface 518 for directing light in a
direction along a substantially horizontal direction from the sides
of side emitting LED's 508, 510, 512. Another convex surface 520
allows light from the top or side of LED's 508, 510, 512 to go in a
substantially vertical direction to comply with FAA
regulations.
[0055] As can be seen from FIG. 5B, side emitting LED's 508, 510,
512 are positioned so that at least two of LED's 508, 510, 512 are
visible along a horizontal plane. As shown, the LED's 508, 510, 512
are spaced apart by 120 degrees from a central point 522 and are
equidistantly spaced from each other. However, any arrangement that
allows at least two of LED's 508, 510, 512 to be visible from any
angle when viewed from the ground or in the air above the
ground.
[0056] FIG. 6 illustrates an inset edge light system 600 designed
to be installed in pavement in accordance to an aspect of the
present invention. An inner bottom cover 602 has an opening 603 for
wires 605 to be coupled to plug 604 for supplying power to the LED
control electronics 606. LED control electronics 606 comprises
electronic circuitry for controlling the current and intensity of
side emitting LED 608. Side emitting LED 608 can be any side
emitting diode such as a Luxeon LXHL-FB1C or LXHL-FB5C having the
desired optical characteristics, e.g., color, intensity. A glass or
acrylic dome 610 of constant thickness covers the side emitting
diode. Dome 610 is clear since system 600 is designed to be
installed in the pavement, thus no visual guidance is given when
the light fixture is off. Furthermore, the slope of dome 610
typically ranges from 0 to 20 degrees to comply with FAA
regulations and dome 610 is designed to bend the light from side
emitting LED 608 at the proper angles, typically 0 to 6 degrees to
comply with FAA requirements. Side emitting LED 608 is mounted on
prism clamp and LED heatsink 616. Prism clamp and LED heatsink 616
is preferably machined to hold dome 610 in place. Top cover 614
secures dome 610 to the surface of prism clamp and LED heatsink
616, and secures prism clamp and LED heatsink 616 to bottom cover
602. Sealing gasket 612 sealingly engages dome 610 with top cover
614 and prevents external contaminants, such as rain, ice or snow,
from getting inside system 600.
[0057] Dome 610 is configured to bend the light from side emitting
diode 608 at the desired angles. For example, by making the slope
of dome 610 approximately 20 degrees and using a 5W, the results
illustrated in Table 1 are obtained. TABLE-US-00001 TABLE 1 Degrees
vertical Candela 0 3.1 1 3.4 2 3.9 3 4.5 4 5.0 5 5.6 6 4.8 7 4.3 8
3.8
[0058] Thus, as can be seen from table 1, the light from side
emitting LED 608 is focused at angles of 0 to 8 degrees and
complies with FAA requirements for an L-852T in-pavement light,
which is 2 candelas from 0 to 6 degrees, and 0.2 candela at all
other angles. Because side emitting LED 608 is much shorter than a
standard incandescent bulb with similar intensity, the height of
dome 610 is lower than for an incandescent bulb. For example, the
distance from the top of dome 610 to the top of top cover 614 can
be as small as a quarter inch.
[0059] FIG. 7 is a circuit diagram of a heater circuit 700 in
accordance with an aspect of the present invention. This heater
circuit can be employed with lighting systems using a side emitting
LED such as heater elements 210 (FIG. 2) 310 (FIG. 3). Because
LED's are more efficient in generating photons than an incandescent
light, they generate much less heat. Heating the lighting system
may be desirable to prevent the accumulation of snow and ice in
cold environments.
[0060] A constant current source 702 supplies current I to circuit
720. The constant current source can be suitably adapted to supply
a constant current at varying levels. For airfield edge lighting
circuits, currents varying between 2.8A and 6.6A are common. The
current I flows into current transformer 704. Current transformer
704 has a primary coil 706 and a secondary coil 708. The ratio of
primary coil 706 to secondary coil 708 is selected to obtain the
desired constant current in secondary circuit 722. For example, if
the ratio of the primary coil to the secondary coil is 1:1, then
the current in circuit 722 will be substantially the same as the
current in circuit 720. Plug 710 couples circuit 722 to the
secondary coil 708 of current transformer 704.
[0061] In accordance with an aspect of the present invention,
circuit 722 is a circuit comprising a LED with associated
electronics 712 in series with a heater element 714. The
electronics portion of the LED with associated electronics 712
comprises a power supply that supplies power to the LED based on
the current flowing through circuit 722. Thermostat 716 is in
parallel with heater element 714. Because a constant current is
flowing through circuit 722, the sum of the currents through heater
element 714 and thermostat 716 will be constant. When heating is
desired, thermostat 716 will provide more resistance, or it can act
as an open circuit, to force more current through heater element
714. When heating is not desired, thermostat 716 provides less
resistance, or it can act as a short circuit, so that less current
will flow through heater element 714. Because circuit 722 is
essentially a series circuit comprising LED with associated
electronics 712 in series with the combination of heating element
714 and thermostat 716 with a constant current source, the
operation of heating element 714 does not effect the operation or
intensity of light from the LED because a constant current flows
through the LED power supply. Circuit 720 can also have additional
current transformers 718 allowing additional lighting systems (not
shown) to be connected.
[0062] While the present system has been illustrated by the
description of embodiments thereof, and while the embodiments have
been described in considerable detail, it is not the intention of
the applicants to restrict or in any way limit the scope of the
appended claims to such detail. Additional advantages and
modifications will readily appear to those skilled in the art.
Therefore, the system, in its broader aspects, is not limited to
the specific details, the representative apparatus, and
illustrative examples shown and described. Accordingly, departures
may be made from such details without departing from the spirit or
scope of the applicant's general inventive concept as defined by
the appended claims.
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