Note: Descriptions are shown in the official language in which they were submitted.
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BEAMFORMER FOR A REMOTELY ILLUMINATED
LIGHTING SYSTEM AND METHOD
Background of the Invention
1. Cross-Reference to Related Applications
The present application is related to commonly assigned United States Patent
Application Serial No. 081733,940 entitled "Integrated Beamformer and Method
of
20 Manufacture Thereof' filed October 21, 1996, the disclosure of which is
hereby
expressly incorporated herein by reference. The present application is also
related to
commonly assigned United States Patent Application entitled "Lighting System
Sequencer and Method" filed of even date herewith, the disclosure of which is
hereby
expressly incorporated herein by reference.
IS
2. Field of the Invention
The present invention relates generally to lighting systems. More
particularly,
the present invention relates to remotely illuminated lighting systems, and to
a
beamforming device, or luminaire, for use in a remotely illuminated lighting
system to
20 provide a controlled, precise and dynamic light distribution pattern.
3. Discussion of the Related Art
Airports incorporate a system of lighting to provide guidance to approaching
aircraft. The conventional aircraft approach lighting system (ALS) includes
groups of
25 incandescent lamps distributed over a field, lighting several thousand feet
of the
approach to the runway within specific requirements for angular light
distribution, color
and intensity. A major problem with the use of incandescent lamps in the ALS
lies with
monitoring the many light sources, i.e., each incandescent lamp, for failure.
The
availability of the ALS is dependent on the number and location of failed
lamps in the
30 system. Lamp replacement is a significant cost owing to the required human
and
equipment resources and the cost of the lamps.
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Federal Aviation Administration (FAA) regulations dictate numerous
requirements for the ALS. For example, the towers upon which the lamps are
mounted
must, between the runway threshold and the 1000-foot bar, be of fragile or
semi-fragile
construction so as to minimize hazards to landing and departing aircraft. Yet,
they must
S also be sufficiently rigid so as to support the lamps under widely varying
weather
conditions. Additionally, depending on the time of day and weather conditions,
the
system must be capable of providing up to five illumination intensity levels.
Existing
systems utilizing incandescent lamps include sophisticated control systems to
provide and
monitor lamp currents to achieve the required illumination intensity levels.
System
performance is inferred from measured lamp currents, which for several reasons
such as
lamp type, aging and current loop resistance differences, may not paint an
accurate
picture of system performance.
Another application of lighting system technology is the illumination of
marine
vessels, aircraft and motor vehicles for navigation and identification. These
navigation
1 S and identification lighting systems must also conform to rigid
multinational regulations
and requirements as to light intensity, angular distribution and color. The
most common
technology for achieving these requirements is a distributed system of
incandescent
lamps coupled to an electrical distribution system. Distributed electrical
systems present
a number of maintenance considerations, such as monitoring for and replacing
failed
lamps, design considerations, such as isolating electromagnetic interference
(EMI) and
safety considerations, such as reducing and/or eliminating ignition sources,
for example,
to fuel spilled during an accident.
In commonly assigned United States Patent No. 5,629,996 a vast improvement
over existing illumination technologies is provided. The system disclosed and
described
therein, which may be referred to as a remote source lighting (RSL) system,
incorporates a centralized light source or light engine. The light source is
coupled via a
light pipe system to one or more beamformers. Each beamformer, or luminaire,
includes a light transformer and holographic diffuser for providing a desired
light
distribution with minimum intensity loss. System performance is directly,
optically
monitored. Centralized lighting sources with enhanced operational life greatly
reduce
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maintenance. While, cool operating, spark free beamformers provide safer,
reduced
cost illumination suitable for use in any number of operating environments.
While great improvements to existing lighting system technology are at hand,
further enhancements may be made through enhancement and control of the light
distribution from the beamformer. For example, light distribution patterns
from high
intensity incandescent lamps is typically fixed and limited to a 180°
distribution pattern
in a horizontal plane. Certain lighting applications, such as mast head
navigation lights
for marine vessels, require horizontal distribution patterns in excess of
180°, and thus
require multiple lamps or beamformers. It would also be desirably to have the
ability to
adapt the light distribution for a particular application, and to be able to
readapt the Iight
distribution for another application. Still more desirable would be an ability
to
dynamically alter the light distribution pattern. Present systems for
providing dynamic
light distribution patterns, such as rotating beacon applications, require
mechanical drive
elements for physically rotating the light source. Thus, there is a need for a
beamforming device that provides enhanced range yet precise lighting
distributions.
There is a further need for a beamformer for use in a remotely illuminated
lighting
system, which provides a precise, adaptable and dynamic Iight distribution
pattern.
Objects of the Invention
It is therefore a primary object of the invention to provide a beamformer
having
an enhanced light distribution pattern.
It is also a primary object of the invention to provide a beamformer having a
highly precise Iight distribution pattern.
It is an additional object of the present invention to provide a beamformer
adaptable to a remotely illuminated lighting system and which provides a
highly precise
light distribution pattern.
Still another object of the present invention is to provide a beamformer
having an
adaptable light distribution pattern.
Yet another object of the present invention is to provide a beamformer having
a
dynamic light distribution pattern.
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An additional object of the present invention is to provide a low cost
beamformer
having little or no operational maintenance.
Another object of the present invention is to provide a lighting system
including a
centralized light source and a fiber optic light distribution system and a
plurality of
beamformers for achieving a precise system of lighting.
A further object of the present invention is to provide a method of providing
a
light distribution pattern.
Other objects, features, and advantages of the invention will become apparent
to
those skilled in the art from the following detailed description and the
accompanying
drawings. It should be understood, however, that the detailed description and
specific
examples, while indicating preferred embodiments of the present invention, are
given by
way of illustration and not of limitation. Many changes and modifications may
be made
within the scope of the present invention without departing from the spirit
thereof, and
the invention includes all such modifications.
1S
Brief Description of the Drawings
Preferred exemplary embodiments of the invention are illustrated in the
accompanying drawings in which like reference numerals represent like parts
throughout, and in which:
Figure 1 is a block diagram schematic of a remotely illuminated lighting
system
incorporating a beamformer in accordance with a preferred embodiment of the
present
invention;
Figure 2 is a schematic representation in side elevation of a beamformer
illustrating the non-imaging light transformer and reflective element thereof
in
accordance with a preferred embodiment of the present invention;
Figure 3 is a schematic representation of a reflective element suitable for
use in
the beamformer shown in Figure 2;
Figure 4 is a schematic representation of a first alternative embodiment of
the
reflective element shown in Figure 2;
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Figure 5 is a schematic representation of a second alternative embodiment of
the
reflective element shown in Figure 2;
Figure 6 is a schematic representation in side elevation of a beamformer
illustrating the non-imaging light transformer, holographic diffuser and
reflective
element thereof in accordance with an alternative preferred embodiment of the
present
invention;
Figure 7 is a schematic perspective representation of a beamformer
illustrating
the non-imaging light transformer, holographic diffuser, diffusion mask and
reflective
element thereof in accordance with an additional alternative preferred
embodiment of the
present invention;
Figure 8 is a plan view of the diffusion mask shown in Figure 7 and an
associated
light distribution pattern;
Figure 9 is a schematic perspective representation of a beamformer
illustrating
the non-imaging light transformer and reflective element thereof in accordance
with
another alternative preferred embodiment of the present invention;
Figure 10 is a perspective view of a diffusion mask in accordance with an
alternative preferred embodiment of the present invention; and
Figure 11 is a schematic perspective representation of a beamformer
illustrating
the non-imaging light transformer and reflective element thereof in accordance
with yet
another alternative preferred embodiment of the present invention.
Detailed Description of the Preferred Embodiments
Resume
A remotely illuminated lighting system distributes from a central illumination
source light signals to remote light distribution devices. Each remote light
distribution
device, or beamformer, is adaptable to produce a highly precise distribution
pattern from
the light signals. The distribution pattern may be easily adjusted in both
horizontal and
vertical directions. In a first preferred arrangement, each beamformer is
coupled via a
fiber-optic cable to the central light source and includes a non-imaging light
transformer
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and a conical reflective element. In additional preferred embodiments, a
holographic
diffuser and/or a masking element are incorporated into the beamformer for
adapting the
shape of the light distribution pattern. An electronically controlled masking
element
may be further incorporated for providing flashing, moving or otherwise
dynamic light
distribution patterns.
2. Remotely Illuminated Lightin~S. stems
Referring now to the drawings, and particularly to Figure 1, a remotely
illuminated lighting system 10 is adaptable for operation as: 1) an approach
lighting
system (ALS), 2) a marine navigation lighting system, 3) an aircraft or motor
vehicle
lighting system 4) an obstruction lighting system or 5) a mine or hazardous
area lighting
system. Numerous other applications of remotely illuminated lighting system 10
are
described in the afore-mentioned U.S. Patent No. 5,629,669, and still many
others may
be envisioned. The remotely illuminated lighting system 10 includes an
illuminator 12
(also referred to as a light engine) providing a centralized source of light
to beamformers
14 via a light delivery system 16. Beamformers 14 may be adapted to: 1)
lighting
towers (such as in an ALS), 2) aircraft, marine vessels and motor vehicles, or
3) remote
andlor hazardous environments (such as mines, explosive manufacturing
facilities,
refineries, laboratories, and the like).
Illuminator 12 includes a controlled power supply 20 suitably coupled to a
source
of electrical energy (not shown) and a direct optical regulator 26. Power
supply 20 and
direct optical regulator are coupled to each other and each are coupled to a
lighting
system controller 18, including a suitable control processor such as a
microprocessor,
for the communication of control signals. Power supply 26 and direct optical
regulator
28 cooperate to control a supply of electrical power to a first light source
22 and a
second light source 24. The light signals output from first light source 22
and second
light source 24 are coupled through optical switch 28 to a high efficiency
coupler 30.
High efficiency coupler 30 couples light output from light sources 22 and 24
via optical
switch 28 to light delivery system 16. Light delivery system 16 preferably
includes an
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optical splitter and a network of fiber-optic bundles for conducting light
signals from
illuminator 20 to one or more beamformers 14.
Each of first light source 22 and second light source 24 preferably generate a
source of energy in the visible range that is concentrated by an elliptical or
parabolic
reflector to a focal spot. The high efficiency coupler 20 couples the light
concentrated in
the focal spot into the optical fibers that form light delivery system 22. As
shown, light
source 24 is preferably a redundant light source. Direct optical regulator 26
is
preferably coupled to optical switch 28 to monitor the light output of both
first light
source 22 and second light source 24. Under normal conditions, only first
light source
22 is supplied electrical power and thus is the only source of light Signals.
Should first
light source 30 fail, the failure is detected by direct optical regulator 26
which causes
signals to be sent to: 1) power supply 20 to cut power to first light source
22 and to
provide power to second light source 24 and 2) optical switch 28 to receive
tight energy
from second light source 24 for coupling to high efficiency coupler 30.
3. Beamformer Assembly
With the exception of beamformer 14, the forgoing described elements of the
present invention are more fully disclosed and preferred constructions
therefore are
discussed in the afore-mentioned United States Patent No. 5,629,996, arid
reference is
made to the description contained therein. With reference now to Figure 2, a
beamformer 14 in accordance with a first preferred embodiment is shown in
schematic
detail. As seen in Figure 2, beamformer 14 includes a light-tight housing 100
having a
generally cylindrical shape including a closed bottom 102, an open top 104 and
a
cylindrical cavity 106. A flanged aperture 112 is formed in bottom 102 for
receiving a
fiber-optic cable coupler. 108. Fiber-optic cable coupler 108 is a suitable
fiber-optic
cable coupler for coupling beamformer 14 to a fiber-optic cable 110 of light
delivery
system 16. Housing 100 is preferably formed from plastic material using an
appropriate
molding process.
Disposed and secured to top 104 is a transparent annular window 110 preferably
constructed from a transparent plastic material. Annular window 110 axially
extends
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cavity 106 and includes a reflective element 112 enclosing an end 114 of
annular
window 110. Reflective element 112 is preferably cone shaped with a pinnacle
116
thereof substantially aligned with a centerline of housing I00 and directed
inwardly
toward cavity 106. Reflective element l I2 includes an angled reflective
surface 118.
More particularly, and best seen if Figures 3 - 5, reflective surface 118 is
formed to an
included angle with respect to the centerline of housing 100. Reflective
element 112
may be formed using either a dielectric or a metallic configuration for
providing
reflective surface 118.
Disposed and secured within cavity 106 is a non-imaging light transformer 120.
Light transformer 120 includes a body portion 126 having a light entrance 122
and a
light exit 124. Light entrance I22 is aligned closely adjacent coupler 108,
and hence,
closely adjacent an end I28 of fiber-optic cable I 10 for coupling light
signals from fiber-
optic cable 110 into light transformer 120. Light transformer 120 is
preferably of a
construction shown and described in the afore-mentioned U.S. Patent No.
5,629,996 for
reducing the light flux density per unit area so as to optimize the energy of
the light
coupled along fiber-optic cable 110 for its intended use in beamformer 14.
Light
transformer 120 may also be of the construction shown and described in the
afore-
mentioned United States Patent Application Serial No. 08!733,940. The
distributed light
signals 130 exit light transformer 120 at light exit 124 and are directed onto
reflective
surface 118 and are reflected outwardly through annular window 110 forming
light
distribution pattern 132. In the embodiment shown in Figure 2, light
distribution pattern
132 extends radially from beamformer 14 in a 360° horizontal pattern
having a vertical
distribution angle
Referring now to Figures 3 - 5, the vertical elevation of light distribution
pattern
132 may be adjusted in beamformer 14 by adjusting the configuration of
reflective
element 112. Figure 3, illustrates reflective element 112 as shown in Figure
2. That is,
reflective element 112 is formed with an included angle of 90°. A light
ray 134
directed axially along housing 100 and striking reflective element 112 is
reflected at an
angle to the centerline of housing 100 that is equal to angle or also
90°. The
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resulting light distribution pattern 132 for reflective element 112 is one
that extends
substantially radially outwardly from beamformer 14.
As shown in Figure 4, reflective element 136 is formed with an included angle
less than 90°. A light ray 134 directed axially along housing 100 and
striking reflective
element 136 is reflected at an angle to the centerline of housing 100 greater
than 90°.
In this manner, the resulting light distribution pattern 132 for reflective
element 136 is
one that is directed upwardly from beamformer 14. As shown in Figure 5,
reflective
element 138 is formed with an included angle greater than 90°. A light
ray 134
directed axially along housing 100 and striking reflective element 138 is
reflected at an
angle to the centerline of housing 100 less than 90°. In this manner,
the resulting light
distribution pattern 132 for reflective element 136 is one that is directed
downwardly
from beamformer 14. As will be appreciated, in controlling the angular shape
of the
reflective element (112, 136 and 138) precise vertical directional control of
the resulting
light distribution pattern 132 of beamformer 14 is obtained.
Referring now to Figure 6, a schematic representation of a beamformer 140 in
accordance with an alternate preferred embodiment of the present invention is
shown.
Beamformer 140 includes positioned between light transformer 110 and
reflective
element 112, a holographic diffuser 142. Holographic diffuser 142 is
preferably a
volumetric device and is adapted to shape the light signals from light exit
124 prior to
striking reflective element 112. In this manner, the light distribution
pattern 132, and in
particular the vertical distribution angle , can be further controlled.
As shown in Figure 6, holographic diffuser 142 is adapted to direct light rays
144
nearest the centerline of beamformer 140 radially inwardly with respect to the
centerline.
Light rays 144 thus strike reflective element 112 at an incident angle less
than 45° and
are thus reflected at an angle ~, less than or less than 90°. In this
manner, light rays
144 are reflected downwardly. Light rays 146 farthest from the centerline of
beamformer 140 are directed radially outwardly with respect to the centerline.
In this
manner, light rays 146 strike reflective element 112 at an incident angle
greater than 45°
and are thus reflected at an angle 2, greater than or greater than 90°.
Light rays 146
are thus reflected upwardly. The resulting overall light distribution pattern
148 for
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beamformer 140 has a vertical distribution angle z greater than . It should be
appreciated that many other light shaping patterns may be introduced by
holographic
diffuser for shaping and controlling the light distribution pattern of
beamformer 140, and
for example, to concentrate the light distribution pattern into a narrow
vertical
distribution.
Referring now to Figures 7 and 8, a beamformer 150 provides a horizontal light
distribution pattern 158 of less than 360°. Beamformer 150 includes
positioned between
holographic diffuser 142 and reflective element 112 a mask element 152. Mask
element
152 includes a substantially transparent portion 154 and a substantially
opaque portion
156. Mask element 152 may be formed from a suitable low loss optically
transparent
material to which a mask coating is applied in the appropriate configuration.
The effect
of mask element 152 is to block light rays exiting light transformer 120 at
light exit 124
from reaching reflective element 112 in predetermined regions. The resulting
light
distribution pattern 158 thus includes a region 162 in which light rays are
reflected from
reflective element 112 as described, and a region 160 in which no light rays
are
reflected. Beamformer 150 is thus suitable for applications requiring a less
than 360°
horizontal light distribution pattern, such as marine vessel mast head
navigation lights.
And, in contrast to the previously noted prior art, a greater than 180°
horizontal light
distribution pattern is possible with a single beamformer 150. Holographic
diffuser 142
is shown and is included to provide a desired vertical distribution angle 2;
however, it
may not be required in every application of beamformer 150. Furthermore, it
will be
appreciated that holographic diffuser 142 may be coated or otherwise provided
with an
opaque region to accomplish the function of mask element 152.
The light distribution pattern 158 may also be achieved utilizing the
beamformer
170 shown in Figure 9. Beamformer 170 includes light transformer 120 and
holographic
diffuser 142 and reflective element 172. In all general aspects, reflective
element 172 is
identical to reflective elements 112, 136 and 138. Reflective element 172
differs in that
a portion 174 of reflective surface 118 is made non-reflective. This may be
accomplished by a number of methods including 1) not coating portion 174 with
reflective material, 2) applying a non-reflective coating to surface 118 in
the area of
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portion 174 or 3) applying a mask to reflective element 172. The effect is
that light rays
striking portion 174 are not reflected, and hence a light distribution pattern
158 is
achieved.
With reference now to Figures 10 and 11, a beamformer 180 and associated
electronically controlled mask 182 is shown. Mask 182 is positioned between
light
transformer 120 and reflective element 112. Mask 182 includes a plurality of
liquid
crystal cells, individually 201 - 220, respectively coupled to a controller
184 by a
plurality of electrical leads 186, and a suitable common ground lead (not
shown). Each
cell 201 - 220 defines an angular portion of mask 182. Controller 184,
preferably
including an appropriate processing device, memory and buffer circuits,
provides
electrical energy to and selectively energizes cells 201 - 220. Energized
cells transition
from a substantially transparent state to a substantially opaque state. As
seen in Figure
9, cells 201 - 203 are energized and are opaque. The remaining cells 204 - 220
remain
transparent. In this configuration, mask 182 is operable to form light
distribution pattern
158 as seen in Figure 8.
With continued reference to Figure 11, all cells 201 - 220 but cell 212 are
energized and opaque. Under operation of controller 184, and in accordance
with an
appropriate sequencing algorithm which may be retained in the memory of
controller
184 or hard programmed in, for example, an application specific integrated
circuit,
adjacent cell 211 is energized as cell 212 is deenergized. Next, and in a like
manner,
cell 210 is energized as cell 211 is deenergized. This process repeats
progressively for
each cell 201 - 220 of mask 182. In this manner, the resulting light
distribution pattern
will have the effect of a beam of light rotating about beamformer 180. Thus, a
rotating
beacon effect is created. As will be further appreciated, all cells 201 - 220
may be
selectively, and concomitantly, energized and deenergized. The resulting light
distribution pattern is that of a flashing beacon, such as an obstruction-
warning beacon.
One will readily appreciate that numerous dynamic light distribution patterns
may be
achieved through the selective energization and deenergization of cells 201 -
220.
Beamformer 180 is shown with 20 cells, namely, cells 201 - 220. The angular
resolution in the horizontal plane is thus approximately 18°. Coarse
and fine resolution
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adjustment may be attained by including less or more cells, respectively, to
mask 182.
In addition, the cells need not be formed as angular sections of mask 182, but
may be
formed in various configurations providing a wide variety of light
distribution patterns.
In certain applications it may be necessary to provide a colored light. For
example, navigation lights are colored red for port, blue for starboard and
white for
stern, respectively. Obstruction lights are typically colored red. In this
regard,
beamformers 14, 140, 150 170 and 180 may include a suitable colored filter
disposed
between light transformer 120 and reflective element 112. In the alternative,
colored
filters or colored light sources may be employed in illuminator 20.
Many changes and modifications could be made to the invention without
departing from the fair scope and spirit thereof. The scope of some changes is
discussed
above. The scope of others will become apparent from the appended claims.
