U.S. patent application number 13/028976 was filed with the patent office on 2011-12-22 for illumination device.
This patent application is currently assigned to MORGAN SOLAR INC.. Invention is credited to John Paul MORGAN.
Application Number | 20110310633 13/028976 |
Document ID | / |
Family ID | 39925147 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110310633 |
Kind Code |
A1 |
MORGAN; John Paul |
December 22, 2011 |
ILLUMINATION DEVICE
Abstract
An illumination device having an optical waveguide stage to
which is optically coupled a light-projecting stage. The
illumination device accepts light from a small isotropic light
source such as a light emitting diode or a bulb coupled to the
optical waveguide stage. The illumination device spreads the light
over a wide area while also collimating it to form a beam.
Alternatively, the light beam can also be shaped in a variety of
ways. The light-projecting stage and the optical waveguide stage
are made of thin slabs of optically transmissive material.
Inventors: |
MORGAN; John Paul; (Toronto,
CA) |
Assignee: |
MORGAN SOLAR INC.
Toronto
CA
|
Family ID: |
39925147 |
Appl. No.: |
13/028976 |
Filed: |
February 16, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12597648 |
Apr 12, 2010 |
|
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PCT/CA08/00847 |
May 1, 2008 |
|
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13028976 |
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Current U.S.
Class: |
362/558 |
Current CPC
Class: |
H01L 31/0547 20141201;
Y10T 29/49826 20150115; G02B 19/0004 20130101; G02B 19/0028
20130101; G02B 19/0019 20130101; G02B 6/0078 20130101; F21S 11/00
20130101; G02B 6/0011 20130101; G02B 6/0038 20130101; H01L 31/02327
20130101; Y02E 10/52 20130101 |
Class at
Publication: |
362/558 |
International
Class: |
F21V 5/00 20060101
F21V005/00; F21V 8/00 20060101 F21V008/00 |
Claims
1. An optical system for processing light from a light source to
provide illumination output, comprising: a stepped waveguide for
collecting input light from a light source and delivering light to
step features of the stepped waveguide; a plurality of optical
elements disposed adjacent each other with each of the plurality of
optical elements including: (a) a redirecting element for receiving
the light from the waveguide and repositioning the light; and (b)
an associated concentrator element which is associated with and
separate from the redirecting element for receiving the light from
the redirecting element and diffusing the light for output
therefrom to provide the illumination, wherein the concentrating
element of each of the plurality of optical elements is separated
from at least one portion of the associated redirecting element by
a layer within which the light does not undergo a repositioning
change of direction and the layer being contiguous between at least
a portion of each of the associated redirecting elements.
2. An optical system for processing light from a light source to
provide illumination output, comprising: a stepped waveguide for
collecting input light from a light source and delivering light to
step features of the stepped waveguide; a plurality of optical
elements disposed adjacent each other with each of the plurality of
optical elements including: (a) a redirecting element for receiving
the light from the waveguide and repositioning the light; and (b)
an associated element which is associated with and separate from
the redirecting element for receiving the light from the
redirecting element and diffusing the light for output therefrom to
provide the illumination, wherein the concentrating element of each
of the plurality of optical elements is separated from at least one
portion of the associated redirecting element by a layer within
which the light does not undergo a repositioning change of
direction and the layer being continuous between at least a portion
of each of the associated redirecting elements.
3. In an optical system for processing light from a light source
with light flow from a collection component and output to provide
an illumination, the improvement comprising: a collection component
including a stepped waveguide for collecting input light from a
light source and delivering light to step features of the stepped
waveguide; a plurality of optical elements disposed adjacent each
other with each of the plurality of optical elements including: (a)
a redirecting element for receiving the light from the waveguide
and repositioning the light; and (b) an associated concentrator
element which is associated with and separate from the redirecting
element for receiving the light from the redirecting element and
diffusing the light for output therefrom, to provide the
illumination, wherein the concentrating element of each of the
plurality of optical elements is separated from at least one
portion of the associated redirecting element by a layer within
which the light does not undergo a repositioning change of
direction and the layer being contiguous between at least a portion
of each of the associated redirecting elements.
4. In an optical system for processing light from a light source
with light flow from a collection component and output to provide
an illumination, the improvement comprising: a collection component
including a stepped waveguide for collecting input light from a
light source and delivering light to step features of the stepped
waveguide; a plurality of optical elements disposed adjacent each
other with each of the plurality of optical elements including: (a)
a redirecting element for receiving the light from the waveguide
and repositioning the light; and (b) an associated element which is
associated with and separate from the redirecting element for
receiving the light from the redirecting element and diffusing the
light for output therefrom, to provide the illumination, wherein
the concentrating element of each of the plurality of optical
elements is separated from at least one portion of the associated
redirecting element by a section of the associated element within
which the light does not undergo a repositioning change of
direction and the layer being contiguous between at least a portion
of each of the associated redirecting elements.
5. In an optical system for processing light from a light source
with light flow from a collection component and output to provide
an illumination, the improvement comprising: a collection component
including a stepped waveguide for collecting input light from a
light source and delivering light to step features of the stepped
waveguide; a plurality of optical elements disposed adjacent each
other with each of the plurality of optical elements including: (a)
a redirecting element for receiving the light from the waveguide
and repositioning the light; and (b) an associated element which is
associated with and separate from the redirecting element for
receiving the light from the redirecting element and diffusing the
light for output therefrom, to provide the illumination, wherein
the concentrating element of each of the plurality of optical
elements is separated from at least one portion of the associated
redirecting element by a section of the associated element within
which the light does not undergo a repositioning change of
direction and the layer being continuous between at least a portion
of each of the associated redirecting elements.
6. An optical system for processing light from a light source to
provide illumination output, comprising: a stepped waveguide for
collecting input light from a light source and delivering light to
step features of the stepped waveguide; a plurality of optical
elements disposed adjacent each other with each of the plurality of
optical elements including: (a) a redirecting element for receiving
the light from the stepped waveguide and repositioning the input
light; (b) an associated concentrator element which is associated
with and separate from the redirecting element for receiving the
light from the redirecting element and diffusing the light for
output therefrom to provide the illumination output, wherein the
concentrating element of each of the plurality of optical elements
is separated from at least one portion of the associated
redirecting element by a layer within which the light does not
undergo a repositioning change of direction and the layer being
contiguous between at least a portion of each of the associated
redirecting elements.
7. An optical system for processing light from a light source to
provide illumination output, comprising: a stepped waveguide for
collecting input light from a light source and delivering light to
step features of the stepped waveguide; a plurality of optical
elements disposed adjacent each other with each of the plurality of
optical elements including: (a) a redirecting element for receiving
the light from the stepped waveguide and repositioning the input
light; (b) an associated element which is associated with and
separate from the redirecting element for receiving the light from
the redirecting element and diffusing the light for output
therefrom to provide the illumination output, wherein the
concentrating element of each of the plurality of optical elements
is separated from at least one portion of the associated
redirecting element by a layer within which the light does not
undergo a repositioning change of direction after exiting the
waveguide and the layer being continuous between at least a portion
of each of the associated redirecting elements.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 12/597,648, having a 371(c) date of Apr. 12, 2010, which is the
U.S. National Stage of International Patent Application No.
PCT/CA2008/000847, filed May 1, 2008. The foregoing applications
and the following applications are incorporated by reference herein
in their entirety: U.S. Provisional Patent Application No.
60/915,207 filed May 1, 2007; U.S. Provisional Patent Application
No. 60/942,745 filed Jun. 8, 2007; and U.S. Provisional Patent
Application No. 60/951,775 filed Jul. 25, 2007.
FIELD OF THE INVENTION
[0002] The present invention relates generally to optics. More
particularly, the present invention relates to light-guiding
collimator and other shaped light beams for less bulky
luminaires.
BACKGROUND OF THE INVENTION
[0003] Luminaires that collimate light from an isotropic source to
form a beam of light are known. The optical elements of the
luminaires can be either lenses or mirrors, and the isotropic light
source can be an incandescent bulb, a fluorescent bulb, or a light
emitting diode. Light is emitted from the bulb in all directions
and interacts with the optical elements, and is redirected to make
a beam in which all the rays of light are substantially
parallel.
[0004] One widespread application for such luminaires is automotive
headlamps. In a typical automotive headlamp, a bulb is positioned
at the focal point of a parabolic reflector. Light emanates from
the bulb in all directions and strikes the parabolic reflector,
which collimates the light into a beam. In general these automotive
headlamps have considerable depth, occupying space in the car.
Other exemplary applications include products such as, amongst
others, stage lighting, flashlights, medical lighting and dentistry
lighting.
[0005] Parabolic reflector can also be upwards of 20 cm deep for an
automotive headlamp and a cover is also required to protect the
bulb and reflector cavity. Additionally, though automotive
headlamps are generally made by injection molding
poly(methyl-methacrylate) (PMMA) or poly carbonate, the clear
polymers must be coated in a reflective mirror coating in order to
operate correctly. The polymers used to make these assemblies are
recyclable with a high recovery value, but the mirror coating
complicates the recycling process and reduces the recovery
value.
[0006] Therefore, it is desirable to provide a collimating
luminaire that is considerably less bulky than existing options.
Alternatively, the light beam can also be shaped in a variety of
ways. It is also desirable to provide a luminaire that does not
need a cover, and which does not require any mirror coatings in
order to function.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to obviate or
mitigate at least one disadvantage of previous illumination
devices.
[0008] In a first aspect, the present invention provides an
illumination device that comprises a light-projecting stage having
at least one optical input aperture, an output surface, and optical
elements formed between the at least one optical input aperture and
the output surface. The device further comprises an optical
waveguide stage optically coupled to the at least one optical input
aperture, the optical waveguide stage having an input surface to
receive light and a waveguide section to guide the light from the
input surface to the at least one optical input aperture, the
optical elements directing the light from the at least one input
aperture to the output surface wherefrom the light exits as a
beam.
[0009] In further aspect, the present invention provides an
illumination device that comprises a first light-projecting stage
having a first at least one optical input aperture, a first output
surface, and first optical elements formed between the first at
least one optical input aperture and the first output surface. The
device also comprises a second light-projecting stage having a
second at least one optical input aperture, a second output
surface, and second optical elements formed between the second at
least one optical input aperture and the second output surface. The
device further comprises an optical waveguide stage optically
coupled to the first at least one optical input aperture and to the
second at least one optical input aperture, the optical waveguide
stage having a first input surface to receive a first light from a
first light source and a second input surface to receive a second
light from a second light source. The optical waveguide further has
a waveguide section to guide the first light from the first input
surface to the first at least one optical input aperture, the first
optical elements directing the first light from the first at least
one input aperture to the first output surface wherefrom the first
light exits as a first beam. The waveguide section also to guide
the second light from the second input surface to the first at
least one optical input aperture and to the second at least one
optical input aperture, the first optical elements and the second
optical elements directing the second light respectively from the
first at least one input aperture to the first output surface and
from the second at least one input aperture to the second output
surface, the second light exiting form the first and second output
surface forming a second beam.
[0010] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of the
invention in conjunction with the accompanying figures and
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Embodiments of the present invention will now be described,
by way of example only, with reference to the attached Figures,
wherein:
[0012] FIG. 1 shows a first embodiment of the light-guide
collimating optic of the present invention;
[0013] FIG. 2 shows an enlarged view of the embodiment of FIG. 1
with light rays entering the collimating stage;
[0014] FIG. 3 shows the embodiment of FIG. 1 with an isotropic
light source at the center of the optic;
[0015] FIG. 4 shows a perspective view of the revolved geometry
embodiment of the light-guide collimating optic of the present
invention;
[0016] FIG. 5A shows the embodiment of FIG. 3 with light rays
exiting the emitter face;
[0017] FIG. 5B shows a perspective view of the embodiment of FIG. 4
in a housing;
[0018] FIG. 5C shows a simple parabolic reflector spot lamp;
[0019] FIG. 5D shows a perspective view of a spot lamp;
[0020] FIG. 6A shows an exploded view of a slab design embodiment
of FIG. 3;
[0021] FIG. 6B shows an intact view of a slab design embodiment of
FIG. 3;
[0022] FIG. 6C shows an enlarged view of a slab design embodiment
of FIG. 3;
[0023] FIG. 7A shows a computer simulation in the XZ plane of the
embodiment of FIG. 3;
[0024] FIG. 7B shows a computer simulation in the YZ plane of the
embodiment of FIG. 3;
[0025] FIG. 7C shows the intensity relief plot from a computer
simulation of the embodiment of FIG. 3;
[0026] FIG. 7D shows the intensity profile from a computer
simulation of the embodiment of FIG. 3;
[0027] FIG. 8 shows an embodiment of the light-guide collimating
optic of the present invention where light rays undergo one or two
reflections in the collimating stage;
[0028] FIG. 9 shows an embodiment of the light-guide collimating
optic of the present invention where parabolic reflectors are
oriented to directed light downwards in the collimating stage;
[0029] FIG. 10 shows an embodiment of the light-guide collimating
optic of the present invention where parabolic reflectors are
oriented to direct light upwards in the collimating stage;
[0030] FIG. 11A shows an embodiment of the light-guide collimating
optic of the present invention where small functional elements are
implemented;
[0031] FIG. 11B shows an enlarged view of the embodiment of FIG.
11A;
[0032] FIG. 12A shows a perspective view of the linear geometry
embodiment of the light-guide collimating optic of the present
invention where the slab design of FIG. 6 and a tube-shaped light
source are implemented;
[0033] FIG. 12B shows a cross-sectional view of the embodiment of
FIG. 12A;
[0034] FIG. 13A shows a perspective view of the revolved geometry
embodiment of the light-guide collimating optic of the present
invention where the slab design of FIG. 6 and the small functional
elements of FIG. 11 are implemented;
[0035] FIG. 13B shows a complete cross-sectional view of the
embodiment of FIG. 13A;
[0036] FIG. 13C shows an enlarged cross-sectional view of the
embodiment of FIG. 13A;
[0037] FIG. 14A shows a perspective view of the broad beam
embodiment of the light-guide collimating optic of the present
invention where a linear geometry describes the functional
elements, a revolved geometry describes the waveguide stage, and
the slab design of FIG. 6 is implemented;
[0038] FIG. 14B shows a complete cross-sectional view of the
embodiment of FIG. 14A;
[0039] FIG. 14C shows an enlarged cross-sectional view of the of
the embodiment of FIG. 14A;
[0040] FIG. 15A shows a computer simulation of the embodiment of
FIG. 14 in the XZ plane;
[0041] FIG. 15B shows a computer simulation of the embodiment of
FIG. 14 in the YZ plane;
[0042] FIG. 15C shows the intensity relief plot from a computer
simulation of the embodiment of FIG. 14;
[0043] FIG. 15D shows the intensity profile from a computer
simulation of the embodiment of FIG. 14;
[0044] FIG. 16A shows a perspective view of the semi-broad beam
embodiment of the light-guide collimating optic of the present
invention where the circular arcs describing the duality of
revolved optics are not concentric with the circumference of the
light-guide collimating optic and the slab design of FIG. 6 is
implemented;
[0045] FIG. 16B shows a complete cross-sectional view of the
embodiment of FIG. 16A;
[0046] FIG. 16C shows an enlarged cross-sectional view of the
embodiment of FIG. 16A;
[0047] FIG. 17A shows a perspective view of the embodiment of FIG.
16 with cylindrical lenses on the emitter face;
[0048] FIG. 17B shows a complete cross-sectional view of the
embodiment of FIG. 17A;
[0049] FIG. 17C shows an enlarged cross-sectional view of the
embodiment of FIG. 17A;
[0050] FIG. 18A shows a perspective view of an embodiment of the
light-guide collimating optic of the present invention where the
optic consists of a circular section of the embodiment of FIG. 16
and the isotropic light source is edge-mounted;
[0051] FIG. 18B shows a complete cross-sectional view of the
embodiment of FIG. 18A;
[0052] FIG. 19 shows an embodiment of the light-guide collimating
optic of the present invention where compound reflectors are used
in the collimating stage and the slab design of FIG. 6 is
implemented;
[0053] FIG. 20 shows an embodiment of the light-guide collimating
optic of the present invention where the collimating stage
containing a large reflector overlaps the waveguide stage and the
slab design of FIG. 6 is implemented;
[0054] FIG. 21 shows an embodiment of the light-guide collimating
optic of the present invention where high beam and low beam
functionality and angular reflectors of FIG. 9 in the collimating
stage are incorporated;
[0055] FIG. 22 shows an embodiment of the light-guide collimating
optic of the present invention where dichroic mirrors encase the
isotropic light source.
DETAILED DESCRIPTION
[0056] Generally, the present invention is a luminaire that uses a
light-guide collimating optic (LGCO), which can also be referred to
as an illumination device. The LGCO accepts light from a small
isotropic light source such as a light emitting diode (LED) or a
bulb and spreads the light over a wide area while also collimating
it to form a beam wherein all the rays are substantially parallel.
The LGCO includes of a thin slab of optically transmissive material
with an emitter face, out of which light emerges collimated, and a
smaller input face, located on the edge of the LGCO. There can be
more than one input face on an LGCO.
[0057] The LGCO has two stages, a waveguide stage (also referred to
as an optical waveguide stage and which includes a waveguide
section) and a collimating stage (also referred to as a
light-projecting stage). Light inserted into the LGCO at an input
face is guided internally by total internal reflection in the
waveguide stage and spreads substantially evenly over the LGCO.
Light then couples into the collimating stage via a multiplicity of
apertures (also referred to as optical input apertures) that allow
light to escape the waveguide stage. The LGCO can be cut
circularly, squarely, or in any other shape. The light beam emerges
substantially collimated. Alternatively, the light beam can also be
shaped in a variety of ways, and made to diverge to any desired
degree in one plane or in two planes.
[0058] It is also possible to build the LGCO such that it accepts
light from two sources so that the emerging light differs with each
source. For example, one could make a high-beam/low-beam
arrangement whereby one bulb produces a beam of light aimed
slightly downward, and another bulb produced a beam in the same
LGCO aimed horizontally or slightly upward.
[0059] FIG. 1 shows the first embodiment of the LGCO 100. Light is
emitted from an isotropic light source 102 placed at the edge 104
(also referred to as an input surface) of the LGCO 100 and emerges
from an emitter face 106 (also referred to as an output surface)
collimated. The LGCO 100 has a waveguide stage 108 into which light
110 from the isotropic source 102 is first inserted and guided. It
also has a collimating stage 114 that shapes and directs the final
beam 112. The waveguide stage 108 and the collimating stage can be
made of any appropriate optical material 116 (e.g., PMMA). The
waveguide stage 108 has one face 118 (also referred to as a first
surface) on its back and a multiplicity of interfaces 120 on its
front side. The face 118 is an interface between the optical
material 116 and the exterior material 122. The exterior material
122 can be a gas or another material of lower index of refraction
than the optical material 116. The multiplicity of interfaces 120
separate the optical material 116 from another material or gas of
lower index of refraction 124. The interface 118 makes a reflector
126 that operates on the light 110 by total internal reflection.
The multiplicity of interfaces 120 also makes reflectors 128 that
operate on the light 110 by total internal reflection. The backside
reflector 126 and the multiplicity of front side reflectors 128 can
be substantially parallel.
[0060] Light 110 traveling in the waveguide stage 108 encounters
apertures 130 (also referred to as optical input apertures), each
of which is an exit location from the waveguide stage 108. At each
subsequent aperture 130, the waveguide stage 108 becomes narrower,
so that the waveguide stage 108 tapers from thickest near the lamp
source 102 to the thinnest at the outside edge of the waveguide
stage 132. At each aperture 130, light 110 exits the waveguide
stage 108 and enters the collimating stage 114. FIG. 2 shows three
rays 110 at different angles exiting the waveguide stage 108 via
the aperture 130 and entering the collimating stage 114. The rays
110 reach an interface 134, which has a parabolic shape. The
interface 134 separates the optical material 136 comprising the
collimating stage 114 from the gas or lower index of refraction
material 124. The interface 134 thus creates a reflector 138 that
operates by total internal reflection--although this reflector 138
can also have a mirrored surface. The light rays 110 impinging on
the reflector 138 can be collimated (made parallel) and immediately
exit the LGCO 100 out the emitter face 106.
[0061] For optimal collimation the reflector 138 is a parabolic
section. However, this reflector can also be a round section, or
any other appropriate shape or a circular approximation of the
optimal parabolic section. For the parabolic case, the parabola 140
which describes the reflector 138 has a focal point 142 which is
coincident with the aperture 130, and the axis of the parabola 144
points in the output direction of the beam--in this case, normal to
the emitter face 106 of the LGCO 100. Light 110 entering the
collimating stage 114 from the aperture 130 can be thought of as
diverging from the focus 142 of the parabola 140 because the focus
142 of the parabola 140 and the aperture 130 are coincident, and
the aperture 130 is narrow. A parabolic reflector 138 collimates
light 110 that is diverging from its focus 142 in a direction
parallel to the axis 144 of the parabola 140.
[0062] The LGCO 100 can be used with a bulb 102 on one edge as
shown previously or with the bulb 102 in the center of the LGCO
100. This is shown in FIG. 3. The cross-section from FIGS. 1-3 can
be made into a linear optic in which case light 110 would be
inserted along the whole edge of the optic 104 (an example is shown
in FIG. 12).
[0063] FIG. 4 shows a revolved LGCO 100 that is shaped like a
discus 146. The cross-section 148 is shown stippled in the figure,
and is the same as FIG. 1. The discus 146 has a hub 150 in its
center that can accept a bulb. Light 110 enters the discus 146 via
a circular wall 152 of the hub 150. Light 110 then propagates as
before and exits as a collimated beam 112 out the emitter face
106.
[0064] In the preceding FIGS. 1-3, if the apertures 130 are
tightened, then a point source is more closely approximated from
the perspective of the parabolic reflectors 138; therefore the
light 110 emerging from the system will be more collimated. If the
apertures 130 are widened, then the opposite happens, and a more
divergent beam will emerge from the LGCO 100. This is a design tool
that can be used to achieve the desired divergence. The tapering of
the waveguide stage 108 depends on the width of the apertures 130,
so narrower apertures 130 will make the waveguide stage 108 taper
more gradually, and wider apertures 130 will make it taper more
quickly.
[0065] FIG. 5 shows a comparison between the LGCO 100 and a simple
parabolic reflector 154. Both optics produce a collimated beam 112,
but the LGCO 100 is considerably more compact along the optical
axis 156 of the collimated light 112. FIG. 5B exemplifies this
compactness using the example of a spot-lamp 158 and a LGCO in a
housing 160 of the same diameter.
[0066] In actuality, it could be difficult to manufacture the LGCO
100 in one piece as shown in FIGS. 1-4. An easier process to mold
the LGCO 100 by injection molding, compression molding, or another
suitable means is to split the LGCO 100 into two slabs which each
have no undercuts and which fit together. These parts can be
dry-fitted together and require no welding or optical bonding.
[0067] The division is shown in FIG. 6, with the waveguide stage
108 comprising one slab 162 and the collimating stage 114
comprising another slab 164. The waveguide stage 108 has exit faces
166 through which light 110 can escape, and it is coupled into the
collimating stage 114 through an injection face 168 abutting the
exit face 166. The exit faces 166 and injection faces 168 make
apertures 130 between the waveguide stage 108 and the collimating
stage 114. FIG. 6 shows light 110 striking the reflectors 138 after
exiting the apertures 130 and making collimated beams 112. In the
present example, the beams 112 emerging from the reflectors 138 in
the collimating stage slab 164 do not cover the whole emitter face
106. There is a dead space 170 where no beam 112 exits the LGCO
100. This creates bands of collimated light. In the case of a
revolved LGCO, the effect would be concentric rings of light
emanating from the optic. In practice however, a small degree of
divergence in the light would render the rings imperceptible beyond
a short distance, and the light exiting the optic would appear as a
unified, solid beam.
[0068] This effect plays out in computer modeling, and FIG. 7 shows
these results. A 20 cm diameter revolved LGCO 100 was modeled and
the profile 174 of the light beam analyzed at a distance of 1 meter
from the optic 100; dimensions on the figure are in centimeters and
the intensity of the beam is on an arbitrary scale. As is clear
from the profiles 174 and the relief plot 176, the beam is roughly
Gaussian. The simulation was done with a finite number of rays and
accounts for the noise in the profiles 174 and relief plot 176.
[0069] FIG. 8 shows rays 178 and 180 exiting the waveguide stage
108 at the apertures 130. Rays exiting the waveguide stage 108 and
entering the collimating stage 114 can go through one of two
processes, both of which are described here. Ray 178 enters the
collimating stage 114, immediately strikes the reflector 138, and
then exits the LGCO 100. Ray 180 enters the collimating stage 114
and reflects off the bottom face 182 of the collimating stage 114
then subsequently off the reflector 138 before exiting the LGCO
100. The face 182 is parallel to the backside face 118 of the
waveguide stage 108. The face 182 is an interface between the
optical material 136 and the gas or lower index of refraction
material 124 between the collimating stage 114 and the wave-guide
stage 108 (not visible in FIG. 8 but shown clearly at FIG. 6C).
This interface 182 makes a reflector 184 operating under total
internal reflection.
[0070] FIG. 8 also shows the parabola 140 that prescribes the
reflectors 138 in the collimating stage 114. This parabola 140 has
its focus 142 coincident with the center of the apertures 130 that
link the waveguide stage 108 and the collimating stage 114, and the
axis 144 of the parabola 140 points in the direction of the beam
112.
[0071] FIG. 9 shows how one can control the direction of the
collimated beam by altering the parabola 140, which is used to
prescribe the reflectors 138. The axis 144 of the parabola 140 has
been angled downward. If this is done while maintaining the focus
142 of the parabola 140 coincident with the center of the apertures
130 then the resultant beam 112 will be collimated and angled
downwards.
[0072] FIG. 10 shows a similar embodiment as FIG. 9 except that the
axis 144 of the parabola 140 has been angled upwards and the
corresponding beam 112 will also be collimated and angled
upward.
[0073] The net result of altering the parabolic reflectors 138 by
tilting the parabola's axis 144 on a revolved LGCO 100 would be to
increase the divergence of the beam 112 emitted from the LGCO 100.
If the optic were linear then the effect of these alterations on
the reflectors 138 would be to aim the beam 112 down or up without
increasing divergence.
[0074] A circular reflector in the collimating stage can be used to
approximate the parabolic reflector and can produce substantially
collimated light. They could also be potentially easier to build.
It may also be the case for certain applications that increased
divergence is desirable, and this can be achieved by chosing
another shape for the reflector, such as, for example, a section of
a circle.
[0075] FIG. 11 shows a LGCO 100 with smaller functional elements
186. The functional elements 186 are defined as: the reflectors
138, the interfaces 120, and the apertures 130 comprised of the
exit faces 166 and the injection faces 168. The optics that have
been shown in the preceding figures have used large functional
elements 186 for explanatory purposes. In actuality, the functional
elements 186 would likely be small, with a period 188 between 1
micron and 1 millimeter. Below 1 micron, optical interference would
likely dominate the performance of the optic 100, and above 1
millimeter in size the necessary diamond tooling becomes
prohibitively expensive. However, larger sizes are possible and
functional, and smaller sizes would also function at wavelengths
below those of visible light.
[0076] The subsequent sections outline specific embodiments of the
technology.
[0077] FIGS. 12A and 12B show a linear LGCO 190 made using a
two-part slab composition with one slab 162 for the waveguide stage
108 and another slab 164 for the collimating stage 114. A tube
shaped bulb 192, in this case a fluorescent bulb, runs down one
edge of the optic. The light emerging from the linear LGCO 190 will
be collimated in the plane YZ and divergent in the plane XZ. This
embodiment has applications in computer displays and lighting.
[0078] FIGS. 13A-13C show a revolved LGCO 194. This optic will
produce a beam like the one from FIG. 7. The diameter of this LGCO
194 is 20 centimeters and the LGCO 194 is approximately 1
centimeter thick at its widest point. The hub 150 has room for an
LED bulb 5 mm in diameter and 7 mm tall, other bulb sizes can be
accommodated by altering the design.
[0079] FIG. 14A-14C shows a hybrid linear/revolved optic 198,
defined here as a broadbeam optic. The functional elements 186 from
FIG. 11 describe the cross section of the linear optic along a
longitudinal axis 200. The backside face 118 of the waveguide stage
108 is revolved and a hub 150 for a bulb is in the center of the
LGCO 198. This LGCO 198 is not as efficient as the previous optic
194 in that more light is lost due to internal scattering. The LGCO
198 collimates light in the plane YZ while letting the light fan
out in the plane XZ. This would be useful for automotive headlamps
where one would want to illuminate a wide-swath of road but where
illumination above the road is not essential. The LGCO 198 produces
a similar beam as the LGCO 190 from FIGS. 12A-12C, except that it
accepts a small point source bulb and does not require a long
tubular bulb.
[0080] Profiles 210 and a relief plot 212 of this broadbeam LGCO
198 are shown in FIGS. 15A-15D.
[0081] There are a number of ways to achieve a broadbeam light
shape. Shown in FIGS. 16A-16C is another LGCO 202, called a
semi-broadbeam optic. The functional elements 186 are prescribed on
circular arcs 204 and 206. The circular arcs are not concentric
with the circumference 208 of the LGCO 202. In the embodiment shown
in FIGS. 16A-16C, the centers of the circles that prescribe the
arcs 204 and 206 are equidistant from the center of the LGCO 202
itself. The resultant beam from the LGCO 202 looks very similar too
that shown in FIGS. 15A-15D, but it is optically more efficient
than the embodiment 198 from FIG. 14.
[0082] FIG. 17 shows the revolved LGCO 194 with cylindrical lenses
214 on the emitter face 106. The resultant LGCO 216 also produces a
broadbeam, which is divergent YZ plane and collimated in the XZ
plane.
[0083] Although the light source (lamp or LED) has previously been
shown in the center of the LGCO, it is possible to edge-mount the
bulb as well. FIGS. 18A-18B show another embodiment of the optic
where this is the case. The bulb 102 is positioned at the edge of
the LGCO 218. The LGCO 218 is formed by taking a circular section
of the LGCO 216 from FIG. 17A-17C. Such sectioning can be done to
make any embodiment edge-lit; furthermore, the sectioning need not
be circular but can be square, triangular, or any appropriate
shape.
[0084] It is possible to make the reflector 138 in the collimating
stage 114 any other sort of reflector, including a compound
reflector 220 as is shown in FIG. 19. This gives more light-shaping
freedom.
[0085] The waveguide stage slab 162 is shown in preceding figures
as tapering to a very fine edge. For structural and fabrication
reasons, the waveguide stage slab 162 may require a minimum
thickness. FIG. 20 shows a wider and larger reflector 222 that can
overlap the outside edge 224 of the waveguide stage slab 162.
[0086] FIG. 21 shows a sectional design for a highbeam/lowbeam LGCO
226. The LGCO 226 accepts light from a central bulb 228 and an
edge-mounted bulb 230. The reflectors 138 in the top half 236 of
the optic 226 are modeled after FIG. 9; they will collimate light
into a downwards pointing beam. The reflectors 138 on the bottom
half 238 of the LGCO 226 will collimate light horizontally.
[0087] When the central bulb 228 emits light 232 this light travels
in both directions within the waveguide stage 108. This light
couples to reflectors 138 in both the top half 236 and the bottom
half 238 of the LGCO 226. The light 232 emitted from the LGCO 226
is comprised of rays aimed downwards coming from the top half 236
and rays traveling horizontally coming from the bottom half
238.
[0088] When the edge-mounted bulb 230 emits light 234 this light
enters the waveguide stage 108 at the bottom edge 240 and travels
in the waveguide stage 108 going upwards only. Light 234 will
bypass all the apertures 130 and remain in the waveguide stage 108
through the bottom half 238 of the LGCO 226. This is because the
apertures 130 allow light to exit the waveguide stage 108 only when
that light is traveling in the direction in which the waveguide
stage 108 is tapering. When light travels the opposite direction in
the waveguide stage 108, it cannot exit at the apertures 130 and
continues to propagate. In the case of the LGCO 226, the light 234
from the edge-mounted bulb 230 will propagate through the bottom
half 238 and into the top half 236 of the waveguide stage 108. The
light 234 will then be traveling in the correct sense so as to pass
through the apertures 130 and reflect off the reflectors 138.
Because the reflectors 138 in the top half 236 of the optic 226 are
oriented so as to aim light downwards, the resulting beam 234 will
be directed downwards. Thus, the LGCO 226 creates a low-beam when
only the edge-mounted bulb 230 is lit and a high-beam when the
central bulb 228 is lit.
[0089] The bulb portion of these designs has not been discussed in
detail, because any bulb can be implemented. FIG. 22 shows an
exemplary embodiment of such a LGCO 242 using a high-heat bulb 244.
This figure shows other innovations specific to such a light
source. A dichroic mirror 246 which reflects infrared radiation 248
is used to separate the lamp 244 from the LGCO 242. This reflects
infrared radiation 248 back towards the lamp 244 while allowing
visible light 250 to enter into the LGCO 242 and to be shaped into
a forward collimated beam 112. A second dichroic mirror 252 that
reflects visible 250 light can be placed underneath the light
source 244 to allow infrared radiation 248 to escape out of the
light-bulb housing 254 while trapping visible light 250 inside so
that it can couple into the LGCO 242.
[0090] Other light-trapping schemes can also be employed to
maximize coupling between the light source and the LGCO. The most
common such scheme will be to put mirrored faces on the bulb or LED
itself in order to avoid light escaping in an undesired
orientation.
[0091] In addition to lamps and bulbs, light can be coupled into
any of the above light-guide collimating optics via a fiber
optic.
[0092] In the preceding description, for purposes of explanation,
numerous details are set forth in order to provide a thorough
understanding of the embodiments of the invention. However, it will
be apparent to one skilled in the art that these specific details
are not required in order to practice the invention. In other
instances, well-known electrical structures and circuits are shown
in block diagram form in order not to obscure the invention. For
example, specific details are not provided as to whether the
embodiments of the invention described herein are implemented as a
software routine, hardware circuit, firmware, or a combination
thereof.
[0093] The above-described embodiments of the invention are
intended to be examples only. Alterations, modifications and
variations can be effected to the particular embodiments by those
of skill in the art without departing from the scope of the
invention, which is defined solely by the claims appended
hereto.
* * * * *