Note: Descriptions are shown in the official language in which they were submitted.
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SYSTEM AND METHOD FOR MANIPULATING ILLUMINATION
CREATED BY AN r~RRAY OF LIGHT EMITTING DEVICES
FIELD OF THE INVENTION
The present invention pertains to the field of optical systems and in
particular to an optical
system incorporating solid-state light emitting devices configured in an
array.
BACKGROUND
Recent innovations in LED design and manufacturing have led to the
introduction of high-
brightness LEDs that produce sufficient luminous flux for architectural and
entertainment
lighting applications. LEDs with different wavelength ranges, for example,
red, green, and blue,
have been combined in arrays with ancillary refractive optics to generate user-
specified colours.
An example of this type of configuration is the Space Cannon MetamorphosisT""
(Space
Cannon vH, Fubine, Italy), wherein an array of red, green, and blue LEDs with
individual
moulded plastic optics, produces a narrow beam of coloured or white light. An
example of a
device that can produce a broad "wash" of coloured or white light is the Color
Kinetics
ColorBlastT"" 12 (Color Kinetics, Boston MA), which provides an array of red,
green, and blue
LEDs 20 mounted behind a frosted or clear tempered glass panel 40, as
illustrated in Figure 1.
The object of these light fixtures is to provide a narrow or broad
distribution of light that has a
uniform colour. However, the arrays of LEDs associated with these particular
products consist of
clusters of individual red, green, and blue LEDs that are ,provided in order
to enable the
satisfactory blending of the individually produced colours, thereby producing
a user-specified
colour on the illuminated surfaces. If, however, the LEDs are arranged in
linear rows of sepaxate
colours, the projected beam of light typically exhibits objectionable colour
gradients at its edges.
In addition, surfaces being illuminated using the above mentioned devices,
that have occluding
objects thereon, results in strong colour banding being visible on the
illuminated surface due to
the shadow cast by this occluding object.
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In addition, the above devices can include moulded plastic optics 30, as
illustrated in Figure 2,
associated with each of the LEDs 20 to provide the control of the
illumination. However these
types of optics are bulky and relatively expensive to manufacture.
Furthermore, these forms of
refractive optics are unable to preferentially redirect emitted illumination
in an off axis direction,
with respect to the plane of the array of LEDs, however this is possible if
the LEDs are mounted
at an angle with respect to the plane of the array. In order to enable this
type of mounting, each
LED could be mounted and wired separately to enable this form or orientation,
however this
would preclude the use of a common circuit board for the mounting of the LEDs,
as is a current
standard, thereby resulting in a more costly device.
A further disadvantage of the prior art is that red, green and blue LEDs
typically require different
drive voltages and can produce ranging colours of light, as such binning of
LEDs is typically
performed, in order to ensure a uniform illumination colour being produced by
an array of LEDs.
As such, LED manufacturers typically offer pre-assembled linear arrays of
single colour LEDs
with matched colours. For example, the Lumileds Line of products (Lumileds
Lighting LLC,
San Jose CA) comprise twelve high-brightness LEDs mounted in a row on a common
printed
circuit board. As has been previously mentioned, linear axrays of LEDs are
difficult to
incorporate into current lighting devices due to the problems of colour
gradients and colour
banding.
The prior art comprises a number documents that define the design and method
of use of
reflector arrays. For example, United States Patent Nos. 6,260,981 and
6,439,736 both define a
luminaire designed to be suitable for suspended ceilings, wherein the design
of this luminaire
enables an improved packing density of these products during shipping. The
reflector is
designed having a grid pattern with a tapered design that allows these
reflectors to be stored and
transported such that one reflector nested within another thereby conserving
space.
United States Patent No. 6,234,643 provides a lighting fixture for reducing
glare and dark spots
on ceilings and walls through the use of direct and indirect reflectors. This
lighting fixture
includes first and second sets of elongated, parallel, spaced apart reflectors
that intersect at a
ninety-degree angle thereby forming an open reflector grid. In addition, the
lighting fixture
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includes a plurality of indirect reflectors connected to the outside walls of
the open reflector grid
which provide a means for reducing glare and dark spots on the ceiling and
walls, which can be
caused by the plurality of fluorescent lamps in the louver housing. This
lighting fixture is
designed specifically for use with fluorescent lamps and as such does not
provide a means for
manipulating the illumination provided by a plurality of discrete light
sources that produce
different wavelengths of illumination.
In addition, the design and method of making an array of optoelectronic
devices is provided in
United Patent No. 5,660,461. The array of LED is formed .from a plurality of
modular units,
wherein a modular unit comprises a light emitting diode and a moulded
reflector unit that has a
cone shape. In order to assemble the array of optoelectronic devices, a
plurality of the modular
units are interconnected by a mechanical snap type connection. As such the
modular units are
fabricated individually and the use of a plurality of LEDs on a linear printed
circuit board, as is
common practice in the art, would not be applicable for this type of design.
The prior art further comprises a number of documents that disclose diffusers
that are used for
blending or distributing illumination in a plurality of directions. For
example, United States
Patent No. 6,447,133 provides an illumination member having a diffuser that
has therein a
plurality of spheres or particles that have a different refractive index when
compared to the
diffuser material itself. As such, the illumination on the output face of the
diffuser can be
controlled by varying the number, size and homogeneity of these spheres or
particles.
Specifically, this diffuser has been designed such that is can be a few
millimetres thick and have
the ability to emit a homogeneously distributed luminance on its output face.
This type of
diffuser is specifically designed for use with a LCD display and provides a
means for controlling
the illumination there from. However this diffuser has not been designed to
provide the blending
of colours produced by a plurality of discrete light sources in close
proximity.
United States Patent No. 6,241,363 provides a coloured light mixing device
that can be
associated with at least one light source set, such that the light source set
has three light
generating units that generate light of different colours. The coloured light
mixing device
comprises a colour mixing plate that is made of transparent material and has a
lower surface that
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has a lower wavelike pattern thereon that faces the light source set, and an
opposite upper surface
that has an upper wavelike pattern thereon. In addition, the upper wavelike
pattern is oriented
differently from the lower wavelike pattern. Upon being hit by light from the
light source set, the
lower wavelike pattern acts as a plurality of linear light sources for mixing
light colours inside
the colour mixing plate and the upper wavelike pattern thereby emits light of
uniform intensity
and mixed hue. This design of a diffuser enables colour mixing specifically
designed for the
situation where there is close proximity between the various colours of light
and therefore may
not be effective in blending illumination produced by a first strip of light
emitting devices
producing a first colour that is flanked by a second strip producing a
different illumination
colour.
Finally, United States Patent No. 6,264,346 provides an apparatus for mixing
light from different
coloured LEDs. This apparatus comprises a faceted diffusive layer that is used
to mix light from
an LED array and is more specifically designed for the creation of white light
from these
different coloured LEDs. This type of apparatus essentially directs all of the
illumination from
the multiple different coloured light emitting diodes in the same direction
thereby combining
them to form the desired illumination colour, namely white light. .
Therefore there is a need for a new method and apparatus for the manipulation
of illumination
created by an array of light emitting devices that is capable of reducing
colour gradients and
colour banding in addition to being optically efficient and capable of
illumination distribution in
an off axis direction of the light emitting device array, while being
applicable for use with strips
of single coloured light emitting devices, as are commonly produced in the
industry.
This background information is provided for the purpose of making known
information believed
by the applicant to be of possible relevance to the present invention. No
admission is necessarily
intended, nor should be construed, that any of the preceding information
constitutes prior art
against the present invention.
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SUMMARY OF THE INVENTION
An object of the present invention is to provide a system and method for
manipulating
illumination created by an array of light emitting devices. In accordance with
an aspect of the
present invention, there is provided a system for manipulating illumination
created by an
array of light emitting devices, said system comprising: a plurality of light
emitting devices
spatially arranged in an array, said array separated into one or more
sections, wherein each
section of the array includes light emitting devices capable of creating
illumination having a
predetermined wavelength range; a macroscopic optical system adjacent to the
plurality of
light emitting devices, said macroscopic optical system enabling redirection
of the
illumination created by the plurality of light emitting devices; and a
microscopic optical
system for diffusing the illumination created by the plurality o~ light
emitting devices
subsequent to the redirection by the macroscopic optical system, thereby
providing a desired
level of blending of the predetermined wavelengths ranges.
In accordance with another aspect of the invention, there is provided a method
for
manipulating illumination created by an array of light; emitting devices, said
method
comprising the steps of redixecting the illumination using reflective optics
formed in a grid
pattern; diffusing the redirected illumination thereby blending the redirected
illumination to
create a desired illumination effect, said diffusing retaining a desired
angular distribution of
the illumination created by the reflective optics.
BRIEF DESCRIPTION OF THE FIGURES
Figure 1 illustrates a prior art configuration wherein illumination from a
light emitting diode is
manipulated by a diffuser panel.
Figure 2 illustrates another prior art configuration wherein illumination
created by a light
emitting diode is manipulated by a moulded refractive optic.
Figure 3 illustrates a ray diagram and the associated vertical cross sectional
view of a
configuration including a macroscopic optical system and a microscopic optical
system used
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together to manipulate illumination created by a plurality of light emitting
devices, according to
one embodiment of the present invention.
Figure 4 illustrates a horizontal cross sectional view of the configuration
including a macroscopic
optical system and a microscopic optical system used together to manipulate
illumination created
by a plurality of light emitting devices, according to the embodiment
illustrated in Figure 3.
Figure 5 illustrates a ray diagram and the associated vertical cross sectional
view of a
configuration including a macroscopic optical system and a microscopic optical
system used
together to manipulate illumination created by a plurality of light emitting
devices, according to
one embodiment of the present invention.
Figure 6 illustrates a horizontal cross sectional view of the conj~guration
including a macroscopic
optical system and a microscopic optical system used together to manipulate
illumination created
by a plurality of light emitting devices, according to the embodiment
illustrated in Figure 5.
Figure 7 illustrates a ray diagram indicating light interaction with a
macroscopic optical system
according to one embodiment of the present invention.
Figure 8 illustrates a ray diagram indicating light interaction with a
macroscopic optical system
according to another embodiment of the present invention.
Figure 9 illustrates an array of light emitting devices having a macroscopic
optical system and
microscopic optical system designed for manipulating light in a predominantly
horizontal
direction, according to one embodiment of the present invention.
Figure 10 is a cross sectional view of the macroscopic optical system
illustrated in Figure 9, as
taken along A-A.
Figure 11 is a cross sectional view of the macroscopic optical system
illustrated in Figure 9, as
taken along B-B.
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Figure 12 is a candela distribution of illumination created by a device having
the elements as
illustrated in Figure 9.
Figure 13 illustrates an array of light emitting devices having a macroscopic
optical system and
microscopic optical system designed for manipulating light in a predominantly
vertical direction,
according to one embodiment of the present invention.
Figure 14 is a cross sectional view of the macroscopic optical system
illustrated in Figure 13, as
taken along C-C.
Figure 15 is a cross sectional view of the macroscopic optical system
illustrated in Figure 13, as
taken along D-D.
Figure 16 is a candela distribution of illumination created by a device having
the elements as
illustrated in Figure 13.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
The term "light emitting device" or "LED" are used interchangeably to define
any form of solid-
state light device enabling the creation of illumination or irradiation, which
includes infrared
radiation, visible light, and ultraviolet radiation.
The term "array" is used to define a geometric layout defining the placement
and arrangement of
light emitting devices. This geometric layout can be one dimensional, for
example linear, or two
dimensional, for example planax.
Unless defined otherwise, all technical and scientific terms useal herein have
the same meaning as
commonly understood by one of ordinary skill in the art to which this
invention belongs.
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The present invention provides an illumination optical system that enables the
direction and
mixing of light from light emitting devices. The optical system comprises a
plurality of light
emitting devices that are spatially arranged in an array, wherein this array
comprises one or more
sections, such that the light emitting devices in a particular section emit
light within a
predetermined wavelength range. Through the use of a combination of
macroscopic and
microscopic optical systems, the illumination created by the array can be
manipulated such that a
desired illumination distribution is created. The macroscopic; optical system
provides a means
for redirecting the illumination in one or more desired directions, wherein
this redirection is
provided by a collection of appropriately shaped and positioned reflective
optics. Subsequent to
its interaction with the macroscopic optical system, the illumination is
manipulated by a
microscopic optical system that enables the diffusion of the illumination in a
predetermined
manner, while retaining the desired angular distribution of the illumination
created by the
macroscopic optical system. Through the appropriate design and orientation of
both the
macroscopic and microscopic optical systems, a desired illumination effect can
be created.
Macroscopic Optical System
The macroscopic optical system provides a means for redirecting the
illumination created by the
point source light emitting devices in one or more desired directions. This
redirection of the
illumination is enabled by a collection of appropriately shaped and positioned
reflective optics
that can preferentially and efficiently redirect light from the light emitting
diodes with a greater
level of efficiency when compared to the use of moulded refractive optics.
The macroscopic optical system is typically designed having reference to a
grid or orthogonal
type pattern and as such, depending on the design of the macroscopic optical
system, the
reflective optics can be oriented in one or both of these orthogonal
directions. Depending on the
design of the reflective optics, the illumination created by the light
emitting devices can be
redirected in a variety of predetermined manners. The following description of
the present
invention, defines the reflective optics associated with the macroscopic
optical system as having
a vertical or horizontal orientation, for ease of understanding. However, it
is to be readily
understood that this type of definition of the orientation of the reflective
optics associated with
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the macroscopic optical system is not limiting, since a rotation of the grid
pattern results in
reflective optics being oriented in a direction other than horizontal or
vertical.
Each embodiment of the macroscopic optical system comprises a plurality of
horizontal
reflectors or reflective optics that enable the preferential redirection of
illumination into the
desired upper portion of the hemispherical luminous intensity distribution of
the light emitting
devices. In this manner an elevated amount of the illumination provided by the
finite number of
light emitting devices within the array can be used to create the desired
illumination effect.
In one embodiment of the present invention the shape, placement and design of
the reflective
optics within the macroscopic optical system can enable a predominantly
horizontal type of
spread of the illumination created by the light emitting devices. In this
embodiment of the
invention, planar horizontal reflective optics are provided adjacent to the 1
or more light emitting
devices in a particular row of the array. Figure 3 and Figure 4 illustrate a
vertical cross section
and horizontal cross section of the optical system according to this
embodiment, respectively.
While these figures illustrate a planar array of light emitting devices, for
example 9 in. total, the
array can equally be linear in design and the macroscopic optical system would
be designed to
suit this shape of array.
Having regard to Figures 3 and 4, the horizontal reflective optics 50, provide
a moderate off axis
distribution of the illumination with a wide beam spread in the vertical
direction. The horizontal
reflective optics include a slot 60 in the upper edge, wherein this slot
allows illumination to
propagate unimpeded into the desired upper portion of the hemispherical
luminous intensity
distribution of the light emitting devices: As illustrated in Figure 3, there
are essentially three
forms of light rays, namely an unobstructed ray 70, a reflected ray, 80 and an
unobstructed slot
ray 90 that together form the illumination that subsequently interacts with
the microscopic optic
system 100.
The slot 60 in the horizontal reflective optics of this embodiment can be
designed having a
number of different shapes, widths and depths, wherein these features of the
slot are determined
based on the luminous intensity distribution and luminous area of the light
emitting devices and
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the packaging thereof. The packaging of the light emitting devices can include
refractive optics
that are integral to the light emitting device itself, thereby varying the
packaging associated with
a light emitting device will alter the dispersion of the illumination created
thereby. In order to
determine the optimum geometrical characteristics of the slot, computer ray
tracing techniques
can be used, wherein this technique can take into account the desired
illumination effect together
with the illumination characteristics of a particular type of light emitting
device.
In another embodiment of the present invention the shape, placement and design
of the reflective
optics within the macroscopic optical system can enable a predominantly
vertical type of spread
of the illumination created by the light emitting devices. In this embodiment
of the invention,
linear, tilted and curved horizontal reflective optics are provided adjacent
to the I or more light
emitting devices in a particular row of the array. In addition, curved
vertical reflective optics are
provided adjacent to either side of the 1 or more light emitting devices in a
particular column of
the array which together form a trough surrounding the light emitting device
in the vertical
direction. Figure 5 and Figure 6 illustrate a vertical cross section and
horizontal cross section of
the optical system according to this embodiment, respectively. While these
figures illustrate a
planar array of light emitting devices, the array can equally be linear in
design and as such the
macroscopic optical system would be designed to suit this type of array.
Having specific regard to Figures 5 and 6, the tilted and curved horizontal
reflective optics 120
provide strong off axis distribution of illumination and further producing a
narrow beam spread
in the vertical direction. Additionally, the curved vertical reflective optics
130 on either side of a
particular light emitting device form a trough and provide a narrow horizontal
beam spread of the
illumination. As an example, this form of narrow horizontal beam spread can be
useful in wall
illumination scenarios. As illustrated in Figure 5, there are essentially two
forms of light rays,
namely an unobstructed ray 70 and a reflected ray, 80 that together form the
illumination that
subsequently interacts with the microscopic optic system 100.
In one embodiment of the invention, the vertical reflective optics 130 are
shaped such that they
create a parabolic trough that surrounds a column of light emitting devices as
illustrated in
Figure 6. This form of vertical reflective optics provides a means for
limiting the Horizontal
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spread of illumination. In this manner a greater percentage of the
illumination created by the
finite number of light emitting devices can be directed towards the
microscopic optical system.
Additionally, the horizontal reflective optics 120 are shaped as an oft=axis
parabola as illustrated
in Figure 5, thereby directing the illumination created by the light emitting
devices i"n a more
vertical direction as indicated by the ray traces 80. According to one
embodiment, the vertical
and horizontal reflective optics can be shaped such that they form a compound
parabolic
concentrator as described by Welford et al, in High Collection Nonimaging
Optics, San
Francisco, Academic Press, 1980. In addition, small modifications in the
curvature, tilt angle,
and position of the horizontal reflectors, in relation to the light emitting
devices, can. alter the
vertical distribution of the illumination emitted by the light emitting
devices, thereby enabling
one to accommodate specific luminous intensity distribution requirements.
The packaging of the light emitting devices can include refractive optics that
are integral to the
light emitting device itself, thereby varying the packaging associated with a
light emitting device
will alter the dispersion of the illumination created thereby. In order to
determine the optimum
geometrical characteristics of the slot, computer ray tracing techniques can
be used, wherein this
technique can take into account the desired illumination effect together with
the illumination
characteristics of a particular type of light emitting device.
In one embodiment of the invention, the reflective optics of the macroscopic
optical system are
fabricated from specular aluminium, a metallised plastic or other form of
stiff reflective material
as would be readily understood by a worker skilled in the art. As an example,
reflective optics
fabricated from a specular aluminium material can provide approximately 95%
efficiency of
illumination redirection.
Microscopic Optical System
Subsequent to interaction with the macroscopic optical system, the
illumination is manipulated
by a microscopic optical system that provides for the diffusion of the
illumination in the desired
manner while retaining control of the desired angular distribution created by
the macroscopic
optical system.
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In one embodiment of the invention, the microscopic optical system
preferentially diffuses light
in the horizontal direction, thereby providing a means for blending
illumination emitted from
columns of light emitting devices. This feature can be advantageous when the
illumination from
various columns of light emitting devices are of varying wavelengths, for
example, red, green,
and blue LEDs. In addition, the horizontal diffusion provided by the
microscopic optical system
can enable the reduction of the appearance of high brightness or illumination
"hot spots" which
can result from the illumination of an area using point light sources like
light emitting devices.
For example, the microscopic optical system can be a holographic diffuser with
a linear or
elliptical distribution, a mechanically-produced plastic diffuser, a
lenticular array or any other
form of diffuser having horizontal diffusion characteristics as would be
readily understood by a
worker skilled in the art. As examples, a suitable holographic diffuser is
called a Light Shaping
Diffuserr"" which is produced by Physical Optics Corporation, Torrance, CA, a
suitable
mechanically-produced plastic diffuser is a Rosco Tough SilkT"", produced by
Rosco Laboratories
Inc., Stamford, CT), and a suitable lenticular array is produced by Fresnel
Technologies Inc., Fort
Worth, TX. While these are examples of suitable microscopic optical systems
enabling
horizontal diffusion of the illumination, a plurality of other devices having
similar characteristics
to those defined would be suitable for integration into the illumination
optical system according
to the present invention.
In another embodiment of the invention, the microscopic optical system
diffuses light evenly in
all directions, wherein diffusers such as a holographic diffuser with circular
distributions, frosted
or sandblasted glass, plastic diffuser, lenslet array or other form of
diffuser having this type of
diffusion characteristic, as would be readily understood by a warker skilled
in the art.
Figures 3 and 5 illustrate ray diagrams representing the illurr,~ination
subsequent to interaction
with a microscopic optical system in the form of a diffixser 100 according to
. different
embodiments of the present invention. As an example, with reference to Figure
5, it can be seen
that the microscopic optical system, in the form of a diffuser 100, is
designed to retain the desired
angular distribution of the illumination previously created by the macroscopic
optical system.
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Figure 7 illustrates the diffusion of an incident ray 140 by a diffuser 100,
wherein the diffused
light 160 is manipulated in a predominantly horizontal manner. Additionally,
Figure 8 illustrates
an incident ray being manipulated such that the illumination or diffused light
150, is diffused in a
predominantly vertical manner.
In one embodiment, holographic diffusers are used as the microscopic optical
system as they
typically have high transmittance of approximately 80 to 90%, which is more
efficient than
frosted glass or plastic diffusers which have a transmittance of approximately
30 to 70%.
Light Emitting Devices
The present invention can be associated with a plurality of light emitting
devices that are
arranged in an array. These light emitting devices can produce any number of
illaxmination
wavelengths and can be arranged in a variety of orders or patterns within the
array. For example,
the plurality of light emitting devices are capable of producing wavelengths
of illumination
including red, green and blue, for example, thereby upon the blending thereof
can enable almost
any colour of illumination to be created. In addition, one or more amber light
emitting devices
can be integrated into the array in order to enhance the colour gamut together
with colour
rendering properties of the array.
In one embodiment of the invention, the light emitting devices are
manufactured on a printed
circuit board. Light emitting devices of different colours require different
drive voltages in
addition to having varying illumination colour creation even within the same
colour band. As
such, the lighting industry performs an organisation routine, typically
referred to as binning, in
order to ensure a uniform illumination colour is being produced by a
collection of light emitting
devices. As such, manufacturers typically offer pre-assembled arrays of single
colour light
emitting devices with matched colours. These forms of arrays can readily be
used in the
illumination optical system according to the present invention. Optionally, a
two dimensional
printed circuit board can be used.
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EXAMPLES
EXAMPLE l: Optical System for Predominantly Horizontal Distribution of
Illumination
In one embodiment of the present invention, the illumination optical system is
designed for a
predominantly horizontal distribution of the illumination created by the light
emitting devices.
Figure 9 illustrates three components of an optical system meeting this
criterion, wherein the
optical system comprises a two dimension array of light emilting devices 205
on collection of
aligned linear printed circuit boards, 200, a macroscopic optical system 210
incorporating
horizontal reflective optics 310 and a microscopic optical system 220 in the
form of a diffuser.
Cross sections A-A and B-B of the illumination optical system are illustrated
in Figures 10
and 1 l, respectively. While the cross section is identified on the
macroscopic optical system, the
cross section illustrates a cross section of the three components together.
The macroscopic optical system that includes a plurality of horizontal planar
reflective optics
aligned with the rows of light emitting devices provides a moderate off axis
distribution of the
illumination, further including a wide beam spread in the vertical direction.
With regard to
Figure 11, the horizontal reflective optics 310 include a trapezoidal slot 320
centred on each light
emitting device, wherein this form of the slot provides a means for allowing
emitted light to
propagate unimpeded into the desired upper portion of the hemispherical
luminous intensity
distribution of light emitting devices. Upon interaction with the macroscopic
optical system the
illumination is diffused by the microscopic optical system 220, providing a
wide horizontal beam
spread which can be applicable for surface illumination applications.
Figure 12 illustrates the luminous distribution of an illumination system
designed in this manner.
EXAMPLE 2: Optical System for Predominantly Vertical Distribution of
Illumination
In one embodiment of the present invention, the illumination optical system is
designed for a
predominantly vertical distribution of the illumination created by the light
emitting devices.
Figure 13 illustrates three components of an optical system meeting this
criteria, wherein the
optical system comprises a two dimension array of light emitv~ing devices 205
on collection of
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aligned linear printed circuit boards, 200, a macroscopic optical system 230
incorporating tilted
and curved horizontal reflective optics 340 and vertical parabolic trough
reflective optics 330,
together with a microscopic optical system 240 in the form of a diffuser.
Cross sections C-C and
D-D of the illumination optical system are illustrated in Figures 14 and 15,
respectively. While
the cross section is identified on the macroscopic optical system, the cross
section illustrates a
cross section of the three components together.
The macroscopic optical system that includes a plurality of horizontal
reflective optics 340 that
are tilted and curved in order to provide strong off axis distribution of the
illumination, while
having a narrow beam spread in the vertical direction. The macroscopic optical
system further
comprises a plurality of vertical reflective optics 330 that are in the form
of a parabolic trough,
thereby providing a means for minimising the horizontal spread of the
illumination. Upon
interaction with the macroscopic optical system the illumination is diffused
by the microscopic
optical system 240 in the form of a diffuser that provides a means retaining
the desired angular
1 S distribution of the illumination created by the macroscopic optical
system.
Figure 16 illustrates the luminous distribution of an illumination system
designed in this manner.
The embodiments of the invention being thus described, it will be obvious that
the same may be
varied in many ways. Such variations are not to be regarded as a departure
from the spirit and
scope of the invention, and all such modifications as would be obvious to one
skilled in the art
are intended to be included within the scope of the following claims.
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