Note: Descriptions are shown in the official language in which they were submitted.
SYSTEMS AND METHODS FOR STABILIZING OPTICAL SHEETS IN LUMINAIRES
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent Application
No. 62/883,037,
filed 5 August 2019; U.S. Patent Application No. 16/879,545, filed 20 May
2020; and U.S. Provisional
Patent Applications No. 63/022,871, filed 11 May 2020.
BACKGROUND
[0002] Luminaires, or light fixtures, for built-in installation may be
designed to meet goals such
as emitted light intensity or distribution, power consumption, cost, size,
mechanical stability, and visual
aesthetics. Realizing certain ones of these goals can present obstacles to
meeting others. For example,
one size goal can be for a luminaire to be as close to flat as possible, for
mounting in low clearance
ceiling applications, hanging on walls and the like. When a flat luminaire is
desired, a typical trade-off in
terms of visual aesthetics is to accept that the luminaire will appear flat.
That is, the luminaire may have
visible brightness or color variations, but will not provide a visible
appearance of having any depth.
Thus, the size goal of providing a flat luminaire can conflict with a visual
aesthetic goal to provide a
three-dimensional look. Goals of providing a high lumen output and/or a
mechanically stable luminaire
can conflict with both the size and visual aesthetic goals. There remains a
need in the lighting arts for
systems and methods that can mitigate these design tradeoffs by allowing more
of the goals to be met
with little to no impact on others of the goals.
[0003] The present application also relates to optical structures that
redirect light. Panel lights
and direct-lit LED-based light fixtures typically include plastic sheets that
diffuse light from light sources,
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Date Recue/Date Received 2020-08-05
such as light-emitting diodes (LEDs) in a uniform manner. Such sheets may be
used alone, or in
combination with other optical and/or structural elements.
SUMMARY
[0004] This summary is provided as a general introduction to some of the
embodiments
described herein, and is not intended to be limiting. Additional example
embodiments including
variations and alternative configurations are provided herein.
[0005] "LED," as used herein, refers to a light emitting diode, which may be
in bare chip form or
packaged form. When LEDs are packaged, there may be one or more bare chips
packaged with any type
of protective structures and/or optics.
[0006] In one or more embodiments, a luminaire includes a housing, a light
source coupled
with the housing, an optical sheet coupled with the housing, and a film
stabilizer coupled with the
housing. The optical sheet includes a first surface and an opposing second
surface that are both
disposed substantially horizontally when the luminaire is in an installed
orientation. The first surface is
disposed facing the light source, so that when the light source emits light,
the light passes first through
the first surface and subsequently through the second surface. The film
stabilizer includes a third
surface and an opposing fourth surface. The film stabilizer is disposed with
the third surface adjacent to
the second surface of the optical sheet, and provides mechanical support for
the optical sheet.
[0007] In one or more embodiments, a luminaire includes a housing, a light
source coupled with
the housing, an optical sheet, and a rigid and transparent film stabilizer
coupled with the housing. The
light source is capable of providing light across an area that is parallel
with the ceiling, wherein a span
length represents a distance across the area. The optical sheet includes a
first surface and an opposing
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second surface. The first surface and the second surface extend substantially
across the area. The first
surface is disposed facing the light source, so that when the light source
emits light, the light passes first
through the first surface and subsequently through the second surface. The
optical sheet is formed of a
flexible material that cannot fully support its weight across the area when
the housing is installed within
the ceiling, such that the optical sheet will sag by an amount that is at
least 0.2% of the span length,
without support at the second surface. The rigid and transparent film
stabilizer includes a third surface
and an opposing fourth surface. The third surface and the fourth surface
extend substantially across the
area. The film stabilizer is coupled with the housing, and is disposed with
the third surface adjacent to
the second surface of the optical sheet. The film stabilizer provides
mechanical support for the optical
sheet so that the optical sheet and the film stabilizer, together, sag less
than 0.1% of the span length.
[0008] In one or more embodiments, a luminaire includes a light source, a
light guide, an
optical sheet, and a film stabilizer. The light guide is configured to receive
a first light from the light
source through an edge of the light guide, and to emit at least a portion of
the first light as a second
light, from a light emitting side surface of the light guide. The optical
sheet includes a first surface and
an opposing second surface. The first surface is disposed adjacent to the
light guide. The optical sheet
receives the second light through the first surface. The second surface emits
a third light with an altered
directionality as compared with the second light. The film stabilizer is
disposed adjacent to the second
surface of the optical sheet, and provides mechanical support for the optical
sheet.
[0009] In one or more embodiments, a light guide is formed of an optical
material and includes
a first edge configured to receive a first light from a light source; a back
surface and a front surface. The
back surface is orthogonal to the first edge, and forms a plurality of light
scattering regions, such that a
portion of the first light is scattered by the light scattering regions to
form a second light. The front
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surface is parallel to the back surface, and forms light redirecting features
that redirect the second light
to form a third light that is emitted from the front surface.
[0010] In one or more embodiments, a luminaire includes a housing that defines
a light output
aperture, a backlight apparatus that is configured to emit light in a light
output direction toward the
light output aperture, and a planar optical sheet of a light transmissive
material. The planar optical
sheet is disposed adjacent the backlight apparatus toward the light output
direction, and is configured
such that when the light passes therethrough, the light is modified by the
planar optical sheet before
leaving the luminaire. The optical sheet forms a first surface and an opposite
second surface, and at
least one of the first surface or the second surface of the optical sheet
includes a plurality of spatial
regions. A first four of the spatial regions are arranged to form an outer
rectangle. Two of the first four
of the spatial regions, on top and bottom sides of the outer rectangle,
include elliptical diffusers that are
oriented predominantly in a first direction that is transverse to the planar
optical sheet, and the other
two of the first four of the spatial regions, on left and right sides of the
outer rectangle, include elliptical
diffusers that are oriented predominantly in a second direction that is
transverse to the planar optical
sheet and is transverse to the first direction. A second four of the spatial
regions are arranged to form
an inner rectangle that is surrounded by the outer rectangle. Two of the
second four of the spatial
regions, on top and bottom sides of the inner rectangle, include elliptical
diffusers that are oriented
predominantly in the second direction, and the other two of the second four of
the spatial regions, on
left and right sides of the inner rectangle, include elliptical diffusers that
are oriented predominantly in
the first direction.
[0011] In one or more embodiments, a method of providing a three-dimensional
(3D)
appearance for a planar output surface of a luminaire includes providing a
backlight apparatus that is
configured to emit light toward a light output direction, and providing a
planar optical sheet capable of
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Date Recue/Date Received 2020-08-05
modifying the light, as it propagates toward the light output direction. The
optical sheet includes a
plurality of first spatial regions that include elliptical diffusers oriented
predominantly in a first direction,
a plurality of second spatial regions that include elliptical diffusers
oriented predominantly in a second
direction, and one or more third spatial regions that include at least one
type of optical microstructure
selected from the group consisting of Fresnel lenses, v-groove lenses, v-cut
lenses, pyramidal lenses,
lenticular lenses, donut lenses and conical diffusers.
[0012] In one or more embodiments, a luminaire includes a housing that defines
a light output
aperture, a backlight apparatus that emits light toward the light output
aperture, and an optical sheet of
a light transmissive material. The optical sheet is disposed adjacent the
backlight apparatus toward the
light output direction, such that the light is modified by the optical sheet
before leaving the light output
aperture. The optical sheet forms a first surface and an opposite second
surface. At least one of the first
surface or the second surface of the optical sheet includes a first spatial
region that includes elliptical
diffusers oriented predominantly in a first direction, a second spatial region
that includes elliptical
diffusers oriented predominantly in a second direction that is different from
the first direction, and a
third spatial region that includes at least one type of optical microstructure
selected from the group
consisting of Fresnel lenses, v-groove lenses, v-cut lenses, pyramidal lenses,
lenticular lenses, donut lenses
and conical diffusers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings are included to provide a further
understanding of the
invention, illustrate embodiments of the invention, and together with the
description serve to explain the
principles of the invention.
Date Recue/Date Received 2020-08-05
[0014] FIG. 1 schematically illustrates, in an upward-looking perspective
view, a luminaire that
includes an optical sheet and a film stabilizer, in accord with one or more
embodiments.
[0015] FIG. 2A schematically illustrates, in an exploded view, certain
components of the
luminaire of FIG. 1.
[0016] FIG. 2B schematically illustrates an extent to which an optical sheet
may sag without
support from a film stabilizer.
[0017] FIG. 2C illustrates what degree of sag may still be present in an
optical sheet when a film
stabilizer is present, in accord with one or more embodiments.
[0018] FIG. 2D schematically illustrates spacing among discrete light sources,
and a distance
between the light sources and a diffuser, that is effective to mitigate
appearance of individual light
sources as seen to a viewer of a luminaire, in accord with one or more
embodiments.
[0019] FIG. 3A schematically illustrates a light source that includes many
individual point light
emitters, that can be used in luminaires described herein, in accord with one
or more embodiments.
[0020] FIG. 3B schematically illustrates a light source that includes several
linear light emitters,
which can be used in luminaires described herein, in accord with one or more
embodiments.
[0021] FIG. 3C schematically illustrates a light source that includes a light
guide that receives
and redistributes light from point emitters, which can be used in luminaires
described herein, in accord
with one or more embodiments.
[0022] FIG. 4 schematically illustrates, in a cross-sectional view, a portion
of a luminaire that
utilizes a light guide, in accord with one or more embodiments.
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Date Recue/Date Received 2020-08-05
[0023] FIG. 5 schematically shows an exemplary optical sheet having an
arrangement of
elliptical diffuser spatial regions and prismatic lens micro-structure regions
arranged to create a 3D
visual effect for a luminaire, according to one or more embodiments.
[0024] FIG. 6A schematically illustrates, a cross-sectional view, a diffuser
micro-structure on an
outer surface of the optical sheet of FIG. 5.
[0025] FIG. 68 schematically illustrates, a cross-sectional view, surface
texture of an individual
elliptical diffuser within one spatial region of the optical sheet of FIG. 5.
[0026] FIG. 6C is an electron microscope photograph, taken in a perspective
view, of exemplary
elliptical diffusers, according to one or more embodiments.
[0027] FIG. 6D is an electron microscope photograph, taken in a perspective
view, of exemplary
prismatic lens structures, according to one or more embodiments.
[0028] FIG. 6E is an electron microscope photograph, taken in a perspective
view, of exemplary
conical diffusers, according to one or more embodiments.
[0029] FIG. 7 schematically illustrates, in a perspective exploded view, a
luminaire in the form
of a panel light assembly, according to one or more embodiments.
[0030] FIG. 8A schematically illustrates, in a cross-sectional view, optical
structures of an optical
subassembly shown in FIG. 7.
[0031] FIG. 88 schematically illustrates, in a cross-sectional view, optical
structures of an
alternate optical subassembly, according to one or more embodiments.
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[0032] FIG. 9 schematically illustrates, in a cross-sectional view, an
exemplary optical sheet
having a combination of prismatic lenses and various diffusers on both an
interior surface and an outer
surface thereof, according to one or more embodiments.
[0033] FIG. 10 illustrates, in a front view, an exemplary picture frame 3D
optical sheet design,
according to one or more embodiments.
[0034] FIG. 11 illustrates, in a front perspective view, the exemplary picture
frame 3D optical
sheet design of FIG. 10.
[0035] FIG. 12 illustrates, in a side perspective view, the exemplary picture
frame 3D optical
sheet design of FIG. 10.
[0036] FIG. 13 shows a front view of an exemplary light assembly configured
with a picture
frame 3D optical sheet design without prismatic accent, according to one or
more embodiments.
[0037] FIG. 14 shows a front view of an exemplary light assembly configured
with a picture
frame 3D optical sheet design with prismatic accent, according to one or more
embodiments.
[0038] FIG. 15 illustrates, in a front view, an exemplary light assembly
configured with a multi-
panel frame 3D optical sheet design, according to one or more embodiments.
[0039] FIG. 16 illustrates, in a side perspective view, the exemplary light
assembly, configured
with a multi-panel frame 3D optical sheet design, of FIG. 15.
[0040] FIG. 17 is a schematic, side elevation of a luminaire that includes a
simplified, recessed
square frame design, having a 3D appearance provided by an optical sheet,
according to one or more
embodiments.
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Date Recue/Date Received 2020-08-05
[0041] FIG. 18 is a schematic, bottom (e.g., upwardly-looking) plan view of
the luminaire of FIG.
17.
[0042] FIG. 19 is a schematic illustration of the optical sheet that provides
the 3D appearance
for the square frame design of the luminaire of FIG. 17, according to one or
more embodiments.
[0043] FIG. 20 is a schematic, side elevation of a luminaire that includes a
more complex,
recessed square frame design, having a 3D appearance provided by an optical
sheet, according to one or
more embodiments.
[0044] FIG. 21 is a schematic, bottom (e.g., upwardly-looking) plan view of
the luminaire of FIG.
20.
[0045] FIG. 22 is a schematic illustration of the optical sheet that provides
the 3D appearance
for the square frame design of the luminaire of FIG. 20, according to one or
more embodiments.
[0046] FIG. 23 is a schematic, side elevation of a luminaire that includes a
simplified, circular
design, having a 3D appearance provided by an optical sheet, according to one
or more embodiments.
[0047] FIG. 24 is a schematic, top (e.g., downwardly-looking) plan view of the
luminaire of FIG.
23.
[0048] FIG. 25 is a schematic illustration of the optical sheet that provides
the 3D appearance for
the circular design of the luminaire of FIG. 23, according to one or more
embodiments.
[0049] FIG. 26 is a schematic, side elevation of a luminaire that includes a
more complex
circular design, having a 3D appearance provided by an optical sheet,
according to one or more
embodiments.
[0050] FIG. 27 is a schematic, top (e.g., downwardly-looking) plan view of the
luminaire of FIG. 26.
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Date Recue/Date Received 2020-08-05
[0051] FIG. 28 is a schematic illustration of the optical sheet that provides
the 3D appearance
for the circular design of the luminaire of FIG. 26, according to one or more
embodiments.
[0052] The drawings represent an illustration of some of the embodiments of
the present
invention and are not to be construed as limiting the scope of the invention
in any manner. Further, the
drawings are not necessarily to scale, some features may be exaggerated to
show details of particular
components. Therefore, specific structural and functional details disclosed
herein are not to be
interpreted as limiting, but merely as a representative basis for teaching one
skilled in the art to
variously employ the present invention.
DETAILED DESCRIPTION
[0053] The subject matter of embodiments of the present inventions are
described here with
specificity to meet statutory requirements, but this description is not
intended to limit the scope of the
claims. The claimed subject matter may be embodied in other ways, may include
different elements or
steps, and may be used in conjunction with other existing or future
technologies. This description
should not be interpreted as implying any particular order or arrangement
among or between various
steps or elements except when the order of individual steps or arrangement of
elements is explicitly
described. Each example is provided by way of illustration and/or explanation,
and not as a limitation.
For instance, features illustrated or described as part of one embodiment may
be used on another
embodiment to yield a further embodiment. Upon reading and comprehending the
present disclosure,
one of ordinary skill in the art will readily conceive many equivalents,
extensions, and alternatives to the
specific, disclosed luminaire types, all of which are within the scope of
embodiments herein.
[0054] In the following description, positional terms like "above," "below,"
"vertical,"
"horizontal" and the like are sometimes used to aid in understanding features
illustrated in the drawings
Date Recue/Date Received 2020-08-05
as presented, that is, in the orientation in which the labels and reference
numerals in each drawing read
normally. These meanings are adhered to, notwithstanding that the luminaires
herein may be
manufactured and/or used in other than the orientations shown.
[0055] As used herein, the terms "comprises," "comprising," "includes,"
"including," "has,"
"having" or any other variation thereof, are intended to cover a non-exclusive
inclusion. For example, a
process, method, article, or apparatus that comprises a list of elements is
not necessarily limited to only
those elements but may include other elements not expressly listed or inherent
to such process,
method, article, or apparatus. Also, use of "a" or "an" are employed to
describe elements and
components described herein. This is done merely for convenience and to give a
general sense of the
scope of the invention. This description should be read to include one or at
least one and the singular
also includes the plural unless it is obvious that it is meant otherwise.
[0056] Specific instances of an item may be referred to by use of a first
numeral followed by a
second numeral within parentheses (e.g., optical sheets 100(1), 100(2), etc.)
while numerals not
followed by a second numeral within parentheses refer to any such item (e.g.,
optical sheets 100). In
instances where multiple instances of an item are shown, only some of the
instances may be labeled,
for clarity of illustration.
[0057] Certain exemplary embodiments of the present invention are described
herein and are
illustrated in the accompanying drawings. The embodiments described are only
for purposes of
illustrating the present invention and should not be interpreted as limiting
the scope of the invention.
Other embodiments of the invention, and certain equivalents, modifications,
combinations, and
improvements of the described embodiments, will occur to those skilled in the
art and all such alternate
embodiments, equivalents, combinations, modifications, and improvements are
within the scope of the
present invention.
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Date Recue/Date Received 2020-08-05
[0058] Certain embodiments herein provide optical layer stacks, portions of
luminaires, and/or
complete luminaires, that are minimal in size, and may include a flat light-
emitting area, yet may provide
a visible sense of depth, and are mechanically stable. For example, in some
luminaire embodiments,
light emitters such as light-emitting diodes (LEDs) inject light into a light
guide that internally reflects the
light until some or all of the light is scattered out of the light guide
toward optical sheets, diffusers and
the like that modify the light distribution. The light guide and the light
emitters provide a luminaire that
is substantially flat, which may have for example a frame that is 2-3 cm
thick, enclosing the light guides
and other structure that are less than 2 cm thick in central areas of the
luminaire. In other luminaire
embodiments, individual light emitters emit light directly toward the optical
sheets, diffusers and the
like; these embodiments may not be as thin as light guide based embodiments.
For example, in some
cases fixture depth is needed to mix and smooth light from individual light
emitters, as discussed below
in connection with FIG. 2D. In either case, light passes through an optical
sheet that may impart a three-
dimensional aspect to the light, that is, the light is modified according to a
spatially varying pattern
within the optical sheet. The pattern can divert light into a different
projected light distribution at each
point. In some embodiments, the modified, projected light can change as a
viewer's angle changes with
respect to the luminaire, so that a luminaire with a generally flat surface
provides a visual impression of
depth (e.g., appears three-dimensional or "3D") even though the luminaire
surface is flat. Luminaires of
any of the types described here can be quite large in light-emitting area,
e.g., 60 x 60 cm (2 x 2 feet), 60
x 120 cm (2 x 4 feet) or larger.
[0059] Certain other embodiments herein relate to the optical sheets that
create the 3D visual
impressions discussed above, through the use of light redirecting elements.
LUMINAIRE INTEGRATION AND MECHANICAL LUMINAIRE FEATURES
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Date Recue/Date Received 2020-08-05
[0060] FIG. 1 schematically illustrates, in an upward-looking perspective
view, a luminaire 100
that includes an optical sheet and a film stabilizer, in accord with one or
more embodiments. Luminaire
100 includes a housing 110 that may form an optional bezel 115, although bezel
115 is not required.
Luminaire 100 emits light from a light-emitting surface 120. Light-emitting
surface 120 may form a
visible image thereon, and the image may be visible when luminaire 100 is
emitting light, and/or turned
off. In FIG. 1, the image formed by light-emitting surface 120 is shown as
resembling a picture frame
that may have a three-dimensional appearance. However, the three-dimensional
appearance is illusory,
and is generated by the optical sheet, which is actually flat, as discussed
below.
[0061] FIG. 2A schematically illustrates, in an exploded view, certain
components of luminaire
100. Housing 110 is shown schematically in an orientation of use, which is
generally horizontal, with
light 10 being emitted generally toward nadir when luminaire 100 is assembled
and operating (FIG. 2A
shows light 10 schematically to facilitate explanation of how the light
interacts with the various
components of luminaire 100). The schematic illustration of FIG. 2A shows
optical components only.
Electrical and/or mechanical components like (but not limited to) wiring,
circuit boards, driving
electronics, fasteners and the like may be present, but are not shown for
clarity of illustration. Portions
of FIG. 2A marked 2B, 2C and 2D respectively are illustrated in further detail
in FIGS. 2B, 2C and 2D.
[0062] A light source 130 emits light 10. The term "light source" herein means
one or more
light emitters as well as direct packaging and mechanical support structure
for the light emitter(s), and
optics that may shape the light from the emitters into an outgoing light
distribution. For example, an
LED chip acting as a light emitter may be packaged with a lens for shaping
light from the chip; the LED
thus packaged may be considered a light source 130, or the packaged LED may be
used in a structure
with additional packaged LEDs and/or optics to form a light source 130.
Certain advantageous light
sources 130 are shown in greater detail in FIGS. 3A, 3B and 3C, and are
discussed further below.
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Date Recue/Date Received 2020-08-05
[0063] In FIG. 2A, an optical sheet 140 redirects and/or modifies intensity of
light 10 so as to
create an image that is discernable at a typical viewing distance from the
luminaire. Optical sheet 140
has a first surface 141 and a second surface 142, both of which are disposed
substantially horizontally
(e.g., within about 30 degrees of horizontal) when luminaire 100 is in an
installed orientation. First
surface 141 faces light source 130, so that when light source 130 emits light
10, the light 10 passes first
through first surface 141 and subsequently through second surface 142.
[0064] Some luminaires of this type exhibit a variety of issues. For example,
optical sheet 140
may exhibit mechanical issues such as drooping or sagging across large
surfaces and/or at elevated
operating temperatures, simply under its own weight. For example, in some
embodiments, an optical
sheet 140 may be formed of thin, somewhat expensive material, such as
polyethylene terephthalate
(PET) as thin as about 250 microns. Conversely, optical sheet 140 may acquire
wrinkles or buckling
during its own fabrication process, which may be mitigated by sandwiching
optical sheet 140 between
two rigid sheets. Optical sheet 140 may also pick up visible fingerprints
during its own fabrication,
and/or during integration into the luminaire 100, or during installation of
the luminaire 100.
[0065] To provide mechanical robustness (and, optionally, other advantages as
discussed
below) a film stabilizer 150 may be provided. Film stabilizer 150 is thick
and/or mechanically strong
enough to hold optical sheet 140 in place within luminaire 100 without
sagging, or at least to reduce
sagging to an amount that is irrelevant in manufacturing and operation of
luminaire 100. Film stabilizer
150 is placed under optical sheet 140, in an orientation of use. Film
stabilizer 150 has a first surface 151
and a second surface 152, both of which are disposed substantially
horizontally when luminaire 100 is in
an installed orientation. First surface 151 of film stabilizer 150 is
generally adjacent to, and/or in contact
with, second surface 142 of optical sheet 140. Film stabilizer 150 is
advantageously substantially
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Date Recue/Date Received 2020-08-05
transparent (e.g., at least 90% transparent), and light weight. Suitable
materials for film stabilizer 150
include, for example, PMMA (polymethyl methacrylate), polycarbonates and
polyethylene.
[0066] In embodiments that utilize a light guide (see FIGS. 3C, 4) optical
sheet 140 may be
sandwiched between the light guide and film stabilizer 150. In embodiments
that use other types of
light emitters (e.g., see FIGS. 3A, 3B) film stabilizer 150 may again be below
optical sheet 140, so that
optical sheet 140 does not sag due to gravity once installed horizontally.
In some of these
embodiments, optical sheet 140 may be sandwiched between a film stabilizer 150
beneath, and a
diffuser 160 above, to mitigate wrinkling or buckling.
[0067] FIG. 2B schematically illustrates an extent to which optical sheet 140
may sag without
film stabilizer 150. In FIG. 2B, the vertical dimension is exaggerated with
respect to the horizontal
dimension. In FIG. 2B, optical sheet 140 is supported only at its left and
right edges, with its top surface
supported at opposite ends of a horizontal line H. Optical sheet 140 sags due
to gravity by an amount
SOS. If optical sheet 140 is, for example, a PMMA sheet of 0.7mm nominal
thickness, it may sag by an
amount SOS of around 3mm across a span of about 570mm (e.g., an inner
dimension of a nominal 2 x 2
foot luminaire for use in a standard modular ceiling). This amount of sagging
amounts to about 0.5% of
the span length at nominal temperatures (but will vary with temperature and
humidity changes) and is
visually evident. This amount of sagging, for example where SOS is at least
0.2% - 1.0% (or more) of a
span length, can also cause other detrimental effects, such as wrinkling upon
incidental contact with
objects during manufacturing, or even spontaneous wrinkling caused by humidity
and/or temperature
cycles.
[0068] FIG. 2C illustrates what degree of sag may still be present in optical
sheet 140, when film
stabilizer 150 is present. In FIG. 2C, film stabilizer 150 is supported such
that again, a top surface of
optical sheet 140 is at opposite ends of horizontal line H. Film stabilizer
150 may be, for example, a
Date Recue/Date Received 2020-08-05
3mm layer of PMMA, and may or may not have surface treatments to provide
diffusion or other light
redirecting properties. While all real world materials will sag somewhat when
unsupported, the extra
stiffness provided by film stabilizer 150 is sufficient to reduce a net sag of
optical sheet 140 to an
amount SpsFs of 0.5mm or less across the same span of about 570mm (e.g., SpsFs
is about 0.1% of the
span length, or less). This is sufficient to avoid the visual and mechanical
problems discussed above.
[0069] Advantageously, film stabilizer 150 may be manufactured with a textured
surface that
minimizes any visual effect due to fingerprints that may be imparted during
manufacturing. When a
textured surface is utilized, the type and orientation of the texturing can be
controlled to provide
diffusion in one or more directions. The degree of diffusion provided can vary
from slight (to preserve
the directionality and/or intensity variations of light as modified by optical
sheet 140) or severe (to
provide substantially unidirectional light output, but possibly blending out
certain effects of optical
sheet 140). In one or more embodiments, the diffusion provided is within a
range of 2 degrees to 10
degrees, and may be about 5 degrees. The diffusion provided by film stabilizer
150 may be different in
different directions transverse to the direction of the light incident
thereon, and may be uniform across
film stabilizer 150, or may vary spatially, similarly to variations provided
by optical sheet 140. For
example, a diffusion pattern provided by film stabilizer 150 may match or
correspond to that provided
by optical sheet 140, or may vary in some other spatial manner. Diffusion
provided by film stabilizer 150
may be greater near the center of luminaire 100 as compared to diffusion
provided at edges of
luminaire 100, or the reverse. The optical performance aspects discussed above
are advantageously not
at the expense of transparency, that is, the film stabilizer should remain at
least 90% transparent while
diffusing or redirecting light. For example, certain regions of an optical
sheet 140 could be configured to
spread light passing therethrough, more in one direction than another, perhaps
spreading the light more
in an X axis than in a Y axis. Then, a surface of an adjacent film stabilizer
150 could also be configured to
16
Date Recue/Date Received 2020-08-05
spread light passing therethrough, more in one direction than another, with
the more-spreading regions
spreading the light more in a direction transverse to the spread of received
light. That is, if the optical
sheet 140 spreads light more across the X axis than the Y axis in certain
spatial regions, the film stabilizer
150 could be configured to spread the light more across the Y axis than the X
axis, in the same spatial
regions. The result would be to provide an output light distribution that is
wider than a typical
Lambertian distribution, in both axes.
[0070] An optional diffuser 160 may also be included in luminaire 100.
Diffuser 160 is
especially useful when light source 130 includes multiple point or line
emitters. The term "point
emitters" herein means a light emitter that provides light across an area less
than 1 cm2 in size. Light
density provided by such emitters can be so high that when discernable within
a luminaire, they are
distracting and/or painful for human viewers to look at. When diffuser 160 is
used as shown, it can
spread light coming from such point emitters so that the light remains
directed in the general direction
of light 10 as shown in FIG. 2A, but light from individual point emitters is
smoothed across a large area
so as to eliminate bright spots when luminaire 100 is viewed from below. A
smooth profile, such as a
Lambertian profile, received at surface 141 of optical sheet 140 works well.
Then, optical sheet 140 and
film stabilizer 150 can be used as described above, starting with input light
intensity that is smoother
across the area of optical sheet 140, to work with. Either or both surfaces of
diffuser 160 may be used
to impart diffusion to the light passing therethrough, and/or, diffuser 160
may be made of a volumetric
diffusing material (e.g., a material with small scattering sites embedded
within the material itself). FIG.
2D, discussed below, illustrates how diffuser 160, and a controlled distance
between point light sources
and diffuser 160, smooth out light provided by point sources across the area
of luminaire 100.
[0071] FIG. 2D schematically illustrates spacing among discrete light sources
131, and a
distance between the light sources 131 and diffuser 160, that is effective to
mitigate an unattractive
17
Date Recue/Date Received 2020-08-05
appearance of individual light sources 131 as seen to a viewer of a luminaire.
Light source 130,
discussed above, can consist of individual light sources 131, one row of which
is shown in FIG. 2D. Some
individual ones of these light sources are labeled as 131(1), 131(2), 131(3)
and 131(4), with ellipses
indicating that further light sources could be present in either direction.
Light sources 131 are typically
arranged in a planar arrangement, give or take normal manufacturing
tolerances. Other arrangements
are possible, but may cause a resulting luminaire to increase in thickness,
which may be undesirable.
Each light source 131 might emit light with a Lambertian intensity pattern,
indicated as a circle with light
ray intensity arrows inside the circle, for each of light sources 131. A
physical pitch between adjacent
ones of the light sources 131 is shown as PLS. Optional diffuser 160, optical
sheet 140 and film stabilizer
150 are shown adjacent to one another (e.g., touching) in FIG. 2D, which is a
possible configuration but
is by no means required.
[0072] The present inventors have found that there is a design tradeoff
involving a distance
DBD between light sources 131 and diffuser 160. Specifically, while keeping
DBD small favors a compact
design, light sources 131 can be so close to diffuser 160 that individual
light sources can easily be seen
by a viewer, which creates an unattractive look. This can be mitigated
somewhat by increasing the
diffusive properties of diffuser 160, but the tradeoff there is that high
diffusion almost necessarily
means low optical efficiency. That is, the light from light sources 131 is
forced to bounce around so
much that quite a bit of it is converted to heat instead of being emitted
through the light fixture. A
typical value of optical transmission for diffuser 160 is about 70% to 75%.
Higher and lower values of
optical transmission are possible, with the understanding that higher values
may not provide enough
diffusion to obscure individual point sources 131, and lower values will
convert more light to heat.
[0073] The present inventors favor a ratio of PLs to DBD of about 1:1, that
is, to provide the
same spacing between light sources as a group, and diffuser 160, as the
horizontal spacing between the
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Date Recue/Date Received 2020-08-05
light sources. In such a case, as can be seen from FIG. 2D, adjacent
distributions have plenty of space to
overlap with one another so that the overall spatial uniformity reaching
diffuser 160 is better than if
diffuser 160 were placed up against light sources 131. It would be possible to
place many individual light
emitters very close to keep PLS small, but that increases part count and cost.
For commercial
embodiments (e.g., those intended to provide lighting across ceiling sections
with a nominal area of 2 x
2 feet, at a typical height of 8 feet above a floor) a useful PLS and DLSD are
both about 1.0 inch, which is
consistent with a light fixture thickness of about 1.5 inches (excluding areas
that may be thicker due to
housing electronic components).
[0074] The present inventors have found that any combination of diffusion
amount provided by
diffuser 160, and distance DLSD, that reduce variations of light intensity
across the area of light at surface
141 of optical sheet 140 to no more than 50% between any two points on optical
sheet 141, is sufficient
to provide a look that does not have distracting light spots. That is, when
not diffused at all, light
provided directly by individual light sources 131 may vary greatly (e.g., by
orders of magnitude) from
light coming from areas between sources 131, but when that variation is
reduced to less than 50% point
to point across an area, the light sources are barely discernible, or not
discernable at all. Not only is this
less distracting, but uniform illumination can greatly enhance the aesthetic
appeal of luminaires having
optical sheets that provide a 3D appearance. This is because the viewer does
not have to dissociate the
visual appearance of bright point sources from the 3D look of the luminaire,
even subconsciously.
Without bright point sources, the 3D look is much more prominent on its own.
[0075] It should be understood that FIG. 2D and the discussion above would
apply equally to
light sources 130 that are formed of line light sources perpendicular to the
plane of FIG. 2D (e.g., see
FIG. 38). That is, the two-dimensional representation of FIG. 2D would simply
be repeated pointwise
down the length of the line light sources, the result being that providing the
same spacing and diffusion
19
Date Recue/Date Received 2020-08-05
properties between line light sources and diffuser 160 would result in
mitigating the appearance of the
line light sources.
[0076] The principles discussed with respect to diffuser 160 can also be
applied to optics that
may be integrated with light source 130. For example, when light source 130
includes point (and/or
linear) light emitters, optics may be included in light source 130 that spread
the points and/or lines of
light into a smoother area distribution emitted toward optical sheet 140.
[0077] It will be appreciated by one skilled in the art that the ability to
control directionality
and/or diffusion at two, three or more separate layers of a luminaire opens up
new lighting possibilities,
especially in commercial indoor lighting. While luminaires typically emit
Lambertian distributions, many
other distributions become possible; for example, in addition to merely
decorative appearance, a
luminaire can provide different and useful lighting distributions such as the
so-called "batwing"
distribution that pushes light into certain corners of an illuminated area.
Volumetric distributions, one-
or two-dimensionally asymmetric, and other distributions are also possible.
[0078] Once a film stabilizer 150 is incorporated, many other, advantageous
variations and
techniques become possible. For example, in one or more embodiments, film
stabilizer 150 can be
adapted to include some or all of the functions of optical sheet 140. That is,
the features on optical
sheet 140 that provide the light shaping properties can be fabricated directly
into, and/or onto, film
stabilizer 150, so that optical sheet 140 can be omitted. Conversely, optical
sheet 140 may be made
thicker so as to have the mechanical rigidity of film stabilizer 150, and may
have the diffusion
characteristics of film stabilizer 150. Additionally, different effects can be
created by orienting the
optically active surface(s) of optical sheet 140 toward or away from diffuser
160. That is, when surface
141 is planar (e.g., surface 142 is the optically active surface) the light
input to optical sheet will be
received within an angular range limited by reflection of some rays at surface
141. Steeper rays will be
Date Recue/Date Received 2020-08-05
refracted into optical sheet 140 at angles determined by the rays' incidence
angles and the refractive
index of optical sheet 140. Some shallow light rays (only a small fraction of
light received at surface 141,
since light emitted as Lambertian is inherently concentrated into steeper
angles) will be reflected from
surface 141 toward the general direction of diffuser 160, and may bounce
around among diffuser 160,
surface 141 and/or housing 110 until dissipated as heat or diverted into
steeper angles. But if surface
141 is the optically active surface, having facets or other surface features
that modify the outward angle
of surface 141 from point to point, light reflected from or entering optical
sheet will be a function of
light angle, refractive index of optical sheet 140 and the angle of surface
141 at every given point.
[0079] FIGS. 3A, 3B and 3C are schematic illustrations of various light
sources 130 that can be
used in luminaires described herein. FIG. 3A schematically illustrates housing
110 with a light source
130(1) that includes many individual point light emitters 131 (only
representative ones of point light
emitters 131 are labeled, for clarity of illustration). Any type of point
light emitters may be used, for
example LEDs or incandescent lights, but LEDs will be typically used, and the
discussion below will refer
to point light emitters 131 as LEDs. Any number of individual LEDs 131 may be
used in light source
130(1), they may couple with housing 110 in any desired manner, and they may
be packaged LEDs or
LED chips. LEDs 131 may also be arranged in any two- or three-dimensional
format; a gridlike layout,
such as illustrated in FIG. 3A, may be used but is not required. LEDs 131 may
be coupled with a printed
circuit board or other known substrate for mounting and supplying power to
LEDs.
[0080] FIG. 3B schematically illustrates housing 110 with a light source
130(2) that includes
several linear light emitters 132 (only representative ones of linear light
emitters 132 are labeled, for
clarity of illustration). Linear light emitters 132 may be formed in a number
of ways, such as for example
rows of LEDs or other point light emitters (individual point emitters are not
labeled in FIG. 3B), or
fluorescent tubes. Either light source 130(1) or 130(2) may include optics to
spread light from point
21
Date Recue/Date Received 2020-08-05
emitters such as LEDs 131, or linear light emitters 132, into broad area light
sources, and may further
collimate the spread-out light for efficient manipulation by optical sheets
140, film stabilizers 150 and/or
diffusers 160, as discussed above.
[0081] FIG. 3C schematically illustrates housing 110 with a light source
130(2) that includes a
light guide 133 that receives and redistributes light from point emitters 131
(only representative ones of
point emitters 131 are labeled, for clarity of illustration). Although FIG. 3C
only shows point emitters
131 emitting light into one side of light guide 133, it is understood that
point emitters may be arranged
about a periphery of light guide 133 in any manner, for example two, three or
four edges of a
rectangular light guide 133, or distributed along a curved edge. Light guide
133 is configured to
substantially contain light received from point emitters 131 by total internal
reflection so that the light
spreads out within light guide 133. Extraction features on either a top or
bottom surface of light guide
133 disrupt the total internal reflection condition so that the light can be
redirected downwards, out of
light guide 133. Type, orientation and density of the extraction features can
vary so as to provide output
light that is well distributed across the lower surface of light guide 133,
avoiding distracting bright spots
corresponding to individual light emitters. Some of these techniques are
described below in connection
with FIG. 8A.
[0082] FIG. 4 schematically illustrates, in a cross-sectional view, a portion
of a luminaire 101.
Luminaire 101 may be considered an example of luminaire 100, FIGS. 1 and 2A,
and of the luminaire
portion shown in FIG. 3C. Luminaire 101 includes a housing 110, a light source
130(3), an optical sheet
140, and a film stabilizer 150. All of light source 130(3), optical sheet 140,
and film stabilizer 150 are
coupled with housing 110. Light source 130(3) includes a light emitter 131
(mounted with a printed
circuit board 118), and a light guide 133 faced with a reflective layer 134. A
first surface of optical sheet
140 is substantially horizontal when luminaire 101 is in an installed
orientation, as shown in FIG. 4
22
Date Recue/Date Received 2020-08-05
(surfaces of optical sheet 140 and film stabilizer 150 are not labeled in FIG.
4 for clarity of illustration,
but are labeled in FIG. 2A). The first surface of optical sheet 140 faces
light source 130(3), so that when
LEDs 131 emit light, the light is redirected by extraction features of light
guide 133 toward optical sheet
140, and the light passes first through the first surface and subsequently
through the second surface of
optical sheet 140. Film stabilizer 150 includes a third surface and an
opposing fourth surface (see FIG.
2A for labeling of these surfaces), is coupled with housing 110, and disposed
so that the third surface is
adjacent to the second surface of optical sheet 140.
[0083] Optical sheet 140 significantly redirects light passing therethrough,
and in some
embodiments has spatial regions that redirect the light in different manners,
so as to create an image
that is discernible at a typical viewing distance from luminaire 101. In other
embodiments, optical sheet
has spatial regions that modify intensity of light passing therethrough, also
to create an image that is
discernible at a typical viewing distance from luminaire 101. In still other
embodiments, optical sheet
140 both redirects and modifies intensity of light passing therethrough. Film
stabilizer 150 provides
mechanical support for optical sheet 140, for example to keep optical sheet
140 from sagging across
large spans of luminaire 101. To provide suitable support for optical sheet
140, film stabilizer 150 may
be formed, for example, of PMMA with a thickness in the range of 0.5mm to
4.0mm between the third
and fourth surfaces as defined above, advantageously with a nominal thickness
of 1.2 - 2.0mm, plus or
minus a normal manufacturing tolerance. Film stabilizer 150 may or may not
significantly redirect light
passing therethrough; in some embodiments film stabilizer 150 provides
diffusion of between two and
ten degrees to the light.
[0084] Housing 110 may provide features that facilitate assembly and/or
performance of
luminaire 101, and other components may also be added to make luminaire 101
mechanically robust
while keeping manufacturing simple and inexpensive. For example, housing 110
may form shelves
23
Date Recue/Date Received 2020-08-05
111(1) and 111(2), as shown in FIG. 4, to simplify assembly of film stabilizer
150, optical sheet 140, and
light guide 133. Film stabilizer 150 and optical sheet 140 may be sized so
that they can be placed on
shelf 111(2) but be surrounded laterally by shelf 111(1). In a typical
assembly process, either printed
circuit board 118 with light emitters (LEDs) 131 may be coupled with housing
110, and film stabilizer 150
and optical sheet 140 may be placed on shelf 111-2, in either order. Then,
light guide 133 and reflective
layer 134 may be placed on shelf 111(1) so as to be adjacent to (and
optionally, in contact with) optical
sheet 140, with edges of light guide 133 positioned so as to capture light
emitted by light emitters 131.
A foam layer 116 can be placed atop reflective layer 134, and a top plate 112
may be placed atop foam
layer 116, with top plate 112 fastened to housing 110 using one or more
fasteners 114 (e.g., a bolt,
screw, rivet or the like). The view of FIG. 4 being at only one point around a
periphery of housing 110,
any number or type of fasteners 114 may be used for a complete luminaire. Foam
layer 116 can yield
slightly under mechanical pressure, to ensure good optical coupling among
light guide 133, optical sheet
140 and film stabilizer 150 while not damaging features of optical surfaces
thereof, and allowing for
looser mechanical tolerances of the optical components and of housing 110. In
some embodiments, the
features of optical sheet 140 and/or film stabilizer 150 can be incorporated
directly onto light guide 133.
That is, the technique of using an optical sheet 140 and/or a film stabilizer
150 with a light guide 133
that has extraction features, can also be generalized into creating a light
guide 133 that has light
extraction features on a top surface, and scattered light steering on a bottom
surface, thereof. The
scattered light steering can impart three-dimensional effects, control
diffusion and the like, as discussed
above.
[0085]
Another issue that can occur with light guides and light shaping films is that
a light
guide and light shaping film can pick up high angle light from the light
emitters (referenced herein as
LEDs, although other light emitters can be used). High angle light can scatter
out of the light guide very
24
Date Recue/Date Received 2020-08-05
near to the LEDs themselves because at high angles, the light will not be
contained within the light guide
by total internal reflection. When this occurs, the edges of the luminaire can
emit a disproportionate
amount of light, compromising spatial uniformity of luminance across the
luminaire (that is, a bright
band of light appears, near the location of the LEDs). This is addressed in
luminaire 101 by providing
shelves 111(1) and 111(2) in housing 110. In addition to simplifying assembly,
shelves 111(1) and 111(2)
also act as light stops for high angle light from light emitters 131, so that
only low angle light propagates
through the light guide and uniformly out of the light shaping film and film
stabilizer.
[0086] Another issue that can arise with use of an edge-lit light guide 133 is
that light density
within light guide 133 can differ between the edges that receive light from
light emitters 131, and the
center of light guide 133. To counteract this effect, in one or more
embodiments the density of
scattering features increases from the edges to the center of the light guide.
Thus, a smaller percentage
of a high density of light is scattered out of the light guide at the edges,
and a larger percentage of a
lower density of light is scattered nearer to the center.
OPTICAL SHEETS THAT CREATE 3D VISUAL IMPRESSIONS
[0087]The optical sheets referred to in the preceding section create three-
dimensional visual
impressions through the use of light redirecting elements. The light
redirecting elements may be
arranged on a nominally flat optical sheet, to form regions with a collective
appearance that simulates
one or more 3D objects. Various ones of the regions can direct light into
certain directions relative to
the optical sheet and relative to one another, such that light intensity from
the various regions changes
when viewing angle with respect to the optical sheet changes. This can create
the visual impression in
the viewer that the regions are actually a three dimensional object, even
though the regions are
arranged in a simple flat plane, or at most a sheet that follows simple
curves. The light redirecting
elements may be micro-structures of varying shapes or orientations, and/or a
combination of prismatic
Date Recue/Date Received 2020-08-05
lenses with such structures, as explained below. The light redirecting
elements and optical sheets
disclosed herein are particularly adapted for use with panel lights and LED
light assemblies.
[0088] Some of these embodiments, and others, are directed to optical sheets
having a micro-
structured pattern of varying shapes and/or orientations of light redirecting
elements, and/or a
combination of prismatic lenses with varying shaped/oriented light redirecting
elements, particularly for
use with panel lights and direct-lit LED light assemblies. An exemplary
optical sheet may include an
arrangement of one or more types of light redirecting elements and/or
prismatic lenses. The
arrangement may be configured to produce various visual effects including
collimated light, diffuse light
and/or combinations thereof. Specifically, an arrangement of light redirecting
elements that are
oriented at different angles with respect to one other can be used to create
varying appearance when
viewed from different viewing angles. Certain combinations of light
redirecting elements and lenses
(such as, but not limited to Fresnel lens structures) can be used to create a
visual impression of depth,
for example. An exemplary 3D optical sheet may have micro-structured pattern
surface regions (e.g.,
regions having a distribution of light redirecting elements arranged thereon)
that produce light emission
angles that are different from one another, with the regions arranged in a
pattern. The different light
redirecting elements may include, but are not limited to, elliptical, conical,
prismatic, v-groove, lenticular
lens, and Fresnel structures; each such type of light redirecting element can
cause light to be
preferentially emitted from the optical sheet at one or more selected angles,
or ranges of angles.
[0089] Light redirecting elements disclosed herein include two types of
diffusers, which are
referred to as "elliptical" or "conical" diffusers respectively. These
elements selectively diffuse and/or
redirect light over one or more angles or angular ranges as a function of
their sizes, orientations, local
density on an optical sheet, and/or mixture with other light redirecting
elements.
26
Date Recue/Date Received 2020-08-05
[0090] "Elliptical" diffusers, as shown and discussed further below, typically
act predominantly
as small cylindrical lenses that either extend from, or are recessed within,
an optical sheet. Physically,
certain embodiments resemble "fibers" that are arranged in a relatively
consistent axial direction on an
optical sheet, with distal surfaces of the diffusers extending from the
optical sheet and proximal surfaces
of the diffusers merged with the sheet. However, these "fibers" are not
completely uniform in direction
or in circumference, they do not repeat at any fixed periodicity, and they do
not typically lie atop the
optical sheet, but rather merge with it. The distal surfaces are typically
long in a predominant axial
direction and curved in a transverse direction. Thus, the distal surfaces may
approximate cylindrical lens
profiles, and may refract light accordingly, that is, light entering an
elliptical diffuser from the proximal
surface (the optical sheet itself) and leaving through the distal surface will
be spread by refraction
transverse to the predominant axial direction of the diffuser. Elliptical
diffusers will generally be
substantially elongated in a predominant axial direction as compared to their
cylindrical radius, usually in a
ratio of at least 10:1, and often up to 100:1 or greater. However, elliptical
diffusers are typically not purely
cylindrical shapes; instead, they may and usually will vary in cross-section,
radius of curvature, shape,
direction and/or length, as shown and described below. These variations add an
element of diffusion to
the refractive spreading discussed above.
[0091] Because of the mechanical properties discussed above, elliptical
diffusers are so named
because of the effect that they provide on light passing through. The effect
can be considered as
transforming a collimated input beam to one that is dispersed into an
elliptical output pattern. That is,
the light passing through the sheet is refracted so as to expand the output
beam significantly in a
direction that is transverse to the dominant axial direction of the "fibers,"
but only minimally along the
axial direction. Variations in diameter of the "fibers," as well as small
deviations of the "fibers" from the
dominant axial direction, expand the output beam somewhat along the axial
direction itself. Thus an
27
Date Recue/Date Received 2020-08-05
input light ray that would otherwise project to a single point will instead
spread to project over an
ellipse that is transverse to the original light ray direction of travel.
[0092] Controlling these physical features - diameters of the "fibers," point
to point variations
in these diameters, the "fibers' " dominant axial directions, and variations
in these axial directions -
allow control over the elliptical refraction characteristics. Films may be
characterized and/or described
by these characteristics. For example, a film that expands a collimated input
beam that passes through
the film, into an output beam that is 70 degrees wide (full width, half
maximum) along the transverse
direction and only 2 degrees wide along the dominant axial direction, may be
characterized as, or called,
a "70 x 2 elliptical film." Such a film would be a fairly extreme case of an
elliptically diffusing film, in that
the transverse beam expansion is much greater than the axial beam expansion. A
film that provides
about half as much expansion along the transverse direction, and about 2 1/2
times the expansion along
the axial direction, may be characterized as, or called, a "35 x 5 elliptical
film." Useful angles of beam
expansion cones for conical diffusers herein are often in the range of at
least twenty degrees in the
transverse direction and less than ten degrees in the axial direction, so that
the effect is directional
enough to trigger a viewer's impression that a viewed object is three-
dimensional rather than a typical,
symmetric diffuser.
[0093] One skilled in the art will also appreciate that elliptical diffusers
may also be formed by
cutting grooves, with physical features that cause the same refractive effects
as discussed below, into an
optical sheet. This is an example of elliptical diffusers not needing to be
actually or even approximately
cylindrical in shape; elliptical diffusers may have other curvatures or
locally planar surfaces that spread
light more in one direction than another. Many alternatives, equivalents and
improvements will be
readily conceived by the skilled practitioner upon reading and understanding
the present disclosure, all
of which are within the scope of this disclosure. For example, elliptical
diffusers of asymmetrical (e.g.,
28
Date Recue/Date Received 2020-08-05
not cylindrical) cross-section may also be formed, and such diffusers may
refract light into asymmetrical
distributions.
[0094] "Conical" diffusers, also shown and discussed further below, typically
resemble
randomly distributed, nonperiodic, rounded shapes with little discernable
axial direction. Distal surfaces
of conical diffusers may be approximately hemispherical, teardrop shaped,
conical, conical lenslets, or
elliptical, but with a limited aspect ratio (up to about 3:1). Proximal
surfaces of the conical diffusers
merge with an optical sheet on which they are located. Light entering a
conical diffuser from the
proximal surface (e.g., the optical sheet itself) and leaving through the
distal surface is generally
scattered in many directions, and for light entering an optical sheet at any
incidence angle, much of the
light may be deviated from that incidence angle.
[0095] Because of the mechanical properties discussed above, conical diffusers
are so named
because of the effect that they provide on light passing through. The effect
can be considered as
transforming a collimated input beam to one that is dispersed into a conical
output pattern. That is, the
light passing through the sheet is refracted so as to expand the output beam
significantly in all directions
that are transverse to the initial direction of the beam. Controlling sizes
and shapes of conical diffuser
features can be used to control the degree of output beam expansion (e.g., a
half angle of an output
cone of light) relative to the input beam. Conical diffuser films may be
characterized and described by
the effect on the input beam. For example, a film that expands a collimated
input beam that passes
through the film, into an output beam that can be considered a dispersion
cone, 30 degrees wide (full
width, half maximum) may be called a 30 degree conical film.
[0096] Thus, areas of an optical sheet having a high density of conical
diffusers will tend to cast
light into many angles, and may thus obscure a point of origin of the light.
This makes areas of conical
diffusers useful in that when small, high output LEDs are used, their light
will be spread over a large
29
Date Recue/Date Received 2020-08-05
area, and the unpleasant experience of a viewer seeing the light as coming
from very bright point
sources can be mitigated.
[0097] Elliptical diffusers, conical diffusers and other diffusers herein may
have a multi-lens
outer surface, such as a curved outer surface, and may be in the shape of a
dome, or bead.
[0098] Prismatic lenses, or simply lens or lenses, as used herein, include
lenses with planar
surfaces in at least one local direction, including Fresnel lenses. For
example, a Fresnel lens that is laid
out as a set of curved lines in plan view, but with spaces between each pair
of curved lines forming a
locally planar surface from one line to other of the pair, would be considered
one form of a prismatic
lens. Prismatic lenses may also be linear or two axis prisms. Prismatic, v-
groove, v-cut, pyramidal,
lenticular, and/or Fresnel lenses are examples of lenses that direct light at
least primarily into one or
two preferred directions from a planar surface of an optical sheet to produce
directed light, which may
include collimated light, which light may be emitted at a single angle, or
different angles, including
asymmetrically.
[0099] An exemplary optical sheet is macroscopically flat, that is, the
optical sheet forms a
planar surface within a small tolerance such as 1 millimeter measured normal
to the planar surface.
Microscopically, the optical sheet is patterned with micro-structured light
redirecting elements such as
those discussed above, and may optionally include further features such as
diffusers and/or lenses,
distributed over various regions of the optical sheet. In an exemplary
embodiment, a first region of the
optical sheet is configured with a light redirecting element of a first type
and/or orientation, and a
second region is configured with a different type or orientation of light
redirecting element, to form a
pattern. For example, a first region of the optical sheet may have a first
type of light redirecting element
and a second region may be configured with a second type of light redirecting
element to form a
pattern. The second orientation may be ninety degrees different from the first
orientation, but other
Date Recue/Date Received 2020-08-05
differences between orientations are possible. A first region of the optical
sheet surface may have a first
type of diffuser and a second region may have a second type of diffuser. A
first region of the optical
sheet surface may have a first type of diffuser that is oriented in a first
direction and a second region
may have the same type of diffuser that is oriented in a second direction or
orientation to produce a
pattern. In many cases, multiple regions are configured with light redirecting
elements in a first
orientation, and other multiple regions are configured with a similar type of
light redirecting elements,
but in a second orientation. A first region of the optical sheet surface may
have a first type of lens and a
second region may have a second type of lens. A first region of the optical
sheet surface may have a first
type of lens that is oriented in a first direction and a second region may
have the same type of lens that is
oriented in a second direction or orientation to produce a pattern. A first
region of the optical sheet
surface may be configured with one or more diffusers, and a second region may
be configured with one
or more lenses. Regions configured with different ones and/or mixtures of the
diffusers and lenses are
also possible. An optical sheet designer who reads and comprehends the present
disclosure will readily
conceive further combinations, improvements, equivalents and alternatives to
the specific examples
provided above, all of which are within the scope of this disclosure.
[00100]
Examples of patterns that can be formed using the features and modalities
described herein include, without limitation, any type of image or design that
would lend itself to a lit
surface with a visual impression of depth. These include picture frames,
simulations of existing
luminaire types (e.g., center basket luminaires and others), geometrical
patterns, logos, trademark
symbols, text letters, words, images, real or imagined topography, abstract
designs, and the like.
Examples created during development include a center-basket luminaire image, a
picture frame, a
picture frame made from quadrants, and a pyramid, as well as numerous abstract
designs using micro
lenses in combinations. Interior and/or outer portions of an optical sheet may
include regions having one
31
Date Recue/Date Received 2020-08-05
type of light redirecting element, prismatic lens or diffuser, and another
region or area with the opposing
type of light redirecting element. In one exemplary embodiment, one type of
light redirecting element is
configured in a polygonal region of the sheet, such as a square, rectangle,
pentagon or any other multi-
sided region. In a further exemplary embodiment, one type of light redirecting
element is configured in
a perimeter region surrounding another type of light redirecting element. In a
further exemplary
embodiment, one type of light redirecting element is configured in a circular
or oval region of the optical
sheet. In a further exemplary embodiment, one type of light redirecting
element in configured in an arc
shaped region of the optical sheet. In a still further exemplary embodiment,
one or more types of light
redirecting elements are configured in regions that form a letter, numeral,
symbol or other text.
[00101]
The light redirecting elements discussed above, for example, diffusers and
micro
lenses having a height of no more than 1000 microns and preferably no more
than 500 microns from an
optical sheet surface, may be arranged to form a micro-structured pattern on
the optical sheet surface.
The micro-structured pattern in the surface of the optical sheet may be an
additive relief pattern,
wherein the light altering elements, diffusers and lenses, extend upwards
(e.g., away) from a reference
surface of the optical sheet. For example, a reference surface may be a local
plane at a height of the
lowest part of all features of the additive relief pattern, (notwithstanding
that the optical sheet may be
curved or otherwise formed on a scale far exceeding that of the light altering
elements). Exemplary
micro diffusers may include a combination of holographically originated random
elliptical and conical
diffusers that may be obtained from WaveFront Technology (Paramount, CA)
having a height of 3 to 20
microns and a radius of curvature of 1 to 50 microns. These and other micro
diffusers and micro lenses
may be micro-structures added to the reference surface (or cut into the
surface, as discussed below).
Such structures may be characterized as having dimensions such as height,
diameter, width, and/or
depth of no more than about 1,000 microns, no more than about 500 microns, no
more than about 250
32
Date Recue/Date Received 2020-08-05
microns, no more than about 100 microns, no more than about 50 microns, and
any range between and
including the dimensions provided, including between 1 and 500 microns; from
the reference surface of
the optical sheet. However, axial dimensions (e.g., length) of elliptical
diffusers are excluded from these
ranges as they may be many times the height, diameter, width, and/or depth of
these structures, as
discussed above.
[00102] Alternatively, light altering elements may be cuts or
indentations into a reference
surface of the optical sheet. For example, an exemplary lens may be formed by
a prismatic groove
having a 3 to 20 micron height and 5 to 100 micron width, with symmetric
and/or asymmetric angles.
[00103] The height and radius ranges above should be understood as
generally applying
to height and/or depth of features relative to a background surface of an
optical sheet. That is,
prismatic lenses and some diffusers, such as elliptical diffusers and/or bead
diffusers, and grooves that
extend across an optical sheet, may have lengths greater than these
dimensions. Such features may be
as long or wide as an optical sheet, or even longer/wider given that they may
form curved shapes within
the optical sheet.
[00104] When an exemplary optical sheet as disclosed herein is used
within a light
assembly having a light guide, the light guide may include extraction features
in a pattern that can be
varied to create a light intensity pattern that complements the optical sheet,
to create additional depth.
For example, an extraction dot pattern may be eliminated in portions of the
light guide that are adjacent
to specific contrast lines in the optical sheet, or the extraction dot pattern
may be made dense adjacent
to portions of the optical sheet that produce bright lines and/or areas. Light
guides used herein are
typically planar to facilitate containing light by total internal reflection
except when the light encounters
extraction features that scatter the light out of the light guide, but
nonplanar light guides are also
possible.
33
Date Recue/Date Received 2020-08-05
[00105] An exemplary light assembly, having a light guide, a back
reflector, and an
optical sheet as disclosed herein, can be further modified to create and/or
enhance 3D imagery to
create additional perceived depth. For example, the back reflector may be
modified to have a pattern
configured therein through painting, screen-printing, UV printing and/or
adhesive laminating a pattern.
One example was made wherein a white pattern was UV printed onto Miro 4
specular highly reflective
metal (which may be obtained from Alanod, Ennepetal Germany) to complement the
front diffuser
pattern.
[00106] Referring now to FIGS. 5, 6A and 6B, an exemplary optical
sheet 300(1) includes
elliptical diffuser spatial regions 310 and prismatic lens micro-structure
regions arranged to create a 3D
visual effect for a luminaire. Optical sheet 300(1) may for example form part
of an optical cover that
modifies light emitted from a backlight apparatus, as it passes toward a light
output direction of a
luminaire (see, for example, FIGS. 7 and 8). The arrangement shown in FIG. 5
is a simple picture frame
design, having elliptical diffusers in four spatial regions 310(1), 310(2),
310(3) and 310(4) that form an
outer square around a perimeter formed of prismatic lenses, and a center, or
inner square, spatial
region 330(1) of conical diffusers. Arrangements of spatial regions with
straight inner and outer sides,
and mitered corners (e.g., corners that meet at angles) that collectively
define a rectangular (including
square) outer perimeter and a rectangular (including square) inner perimeter,
are sometimes called
frame regions herein.
[00107] Because the illustrated arrangement is square, spatial
regions 310(1) through
310(4) are sometimes referred to as quadrants herein. Although optical sheet
300(1) is square, optical
sheets herein may be of any shape suitable for use with a luminaire; square,
rectangular, and rounded
shapes (circular, elliptical, ovoid and the like) are the most common shapes;
these and any other shapes
that can be covered with a planar or curved planar optical sheet 300 are
contemplated. Also, spatial
34
Date Recue/Date Received 2020-08-05
regions that form an outer boundary corresponding to a given shape may be
referred to herein as
having or forming that shape, although they may not fill the shape. For
example, spatial regions 310(1),
310(2), 310(3) and 310(4) are said to form a square, outer square, rectangle
or outer rectangle, even
though those spatial regions do not fill the portion of optical sheet 300(1)
that is occupied by perimeter
spatial region 320(1) and central spatial region 330(1). Perimeter spatial
region 320(1), and central
spatial region 330(1), are likewise central rectangles, inner rectangles,
central squares or inner squares
within the outer square. Furthermore, although spatial regions 310(1), 310(2),
310(3) and 310(4) are
uniform in width (distance from the outer square edge to the inner edge of
each spatial region) spatial
regions that form asymmetric frame-like features are also contemplated (e.g.,
frames with wider side
borders than top and bottom borders, vice versa, and the like).
[00108]
The illustrated arrangement of elliptical diffusers and prismatic lenses
produces
light emission from optical sheet 300 that creates an impression of depth,
even though optical sheet 300
is planar as installed. Orientation of the elliptical diffusers in each
spatial region 310 is such that the
diffusers in adjacent regions are at different angles to one another; in this
case, spatial regions 310(1)
and 310(3) have diffusers that are predominantly left-to-right in the
perspective of FIG. 5, while spatial
regions 310(2) and 310(4) have diffusers that are predominantly top-to-bottom.
Because the diffusers
in the different spatial regions will scatter light differently, this
arrangement creates different light
intensities in each of the quadrants, based on viewing angle, which creates a
visual impression of depth
and contrast among the quadrants. For example, as shown in FIGS. 5 and 6A,
elliptical diffuser spatial
regions 310 may be configured around a prismatic lens portion 320(1), such as
a Fresnel lens border that
extends around centrally located spatial region 330(1) of optical sheet 300.
Lines 2A-2A and 2B-2B
indicate cross-sectional views that are illustrated in FIGS. 6A and 6B,
respectively.
Date Recue/Date Received 2020-08-05
[00109] FIG. 6A schematically illustrates, in a cross-section that
is not drawn to scale, a
diffuser micro-structure on an outer surface of optical sheet 300. The
microstructure includes a
combination of elliptical diffusers 312 in spatial regions 310, prismatic lens
structures 314 in spatial
regions 320(1) and conical diffusers 316 in spatial region 330(1) (only
representative ones of elliptical
diffusers 312, prismatic lens structures 314, and conical diffusers 316 are
labeled, for clarity of
illustration). A transverse direction T is labeled for spatial regions 310(2)
and 310(4) in FIG. 6A, this
direction is transverse to the predominant orientation of elliptical diffusers
312. That is, since elliptical
diffusers 312 act substantially like cylindrical lenses, direction T is
transverse to the cylindrical axes of
individual elliptical diffusers 312. An axial direction A is perpendicular to
the plane illustrated in FIG. 6A.
It should be understood that directions T and A are specific to individual
spatial regions, because they
indicate directions transverse and axial to the diffusers in such regions;
directions T and A can and
usually are different for different spatial regions of an optical sheet 300.
Also, spatial region 330(1) does
not have a transverse or axial direction because conical diffusers 316
associated therewith provide
scattering that does not have directionality such as imparted by elliptical
diffusers 312. Prismatic lens
structures 314 may, or may not, impart a light redirection having an
orientation that is consistent across
spatial region 320(1).
[00110] Diffusers 312 and 316, and prismatic lens structures 314,
are examples of micro-
structures coupled with the optical sheet surface. Diffusers 312 and 316 have
a maximum diffuser
height HD of no more than about 1,000 microns relative to a reference plane
301 of optical sheet 300.
Reference plane 301 is a planar surface that would be present if no
microstructures were added to, or
embossed or cut into, optical sheet 300, and is shown for discussion purposes,
but is not a physical
structure. As shown below in FIG. 6C, elliptical diffusers 312 can resemble
"fibers" on top of, and
merged with, reference plane 301. In FIG. 6A, cylindrical radii of elliptical
diffusers 312 (e.g., height HD
36
Date Recue/Date Received 2020-08-05
of elliptical diffusers 312) range from about one micron to about 5-7 microns,
but these sizes are
exemplary only; cylindrical radii of up to about 1000 microns will perform
substantially similarly. (Above
about 500 microns in radius, individual "fibers" may start to become
undesirably visible to a viewer.)
[00111] FIG. 6B illustrates, in a cross-sectional view that is also
not drawn to scale,
optical sheet 300(1). The illustrated texture imparts some - but not a great
deal of - diffusion along the
labeled axial direction A of elliptical diffusers 312 (axial direction A is
orthogonal to transverse direction
T, which is perpendicular to the plane illustrated in FIG. 6B).
[00112] FIGS. 6C, 6D and 6E are electron microscope photographs,
taken in perspective
views, of exemplary elliptical diffusers 312, prismatic lens structures 314
and conical diffusers 316
respectively.
[00113] Axial direction A and transverse direction T, which are
relevant to elliptical
diffusers 312, are labeled in FIG. 6C. As will be appreciated by one skilled
in the art upon reviewing and
understanding FIG. 6C, elliptical diffusers 312 provide strong redirection of
light passing through, in the
transverse direction T, because they approximate cylindrical lenses with axes
aligned in axial direction A.
Elliptical diffusers 312 also have small variations in size along axial
direction A; these variations provide a
small amount of light scattering along axial direction A. By adjusting the
sizes of elliptical diffusers 312
and the small variations in size along axial direction A, one skilled in the
art can make spatial regions
populated with elliptical diffusers 312 to create various elliptical
dispersions as desired, such as the 70 x
2 and 35 x 5 elliptical films discussed above.
[00114] Prismatic lens structures 314, examples of which are
illustrated in FIG. 6D, may
or may not have a predominant (e.g., fixed) axial direction. For example, the
structures shown in FIG.
6D curve, so in this particular example there is no identifiable axial
direction. However, in other
37
Date Recue/Date Received 2020-08-05
embodiments, prismatic lens structures may be linear or two axis prisms. And,
although there is not an
axial direction, one skilled in the art will be able to provide prismatic
shapes of prismatic lens structures
314 that direct light in one or more desired directions by refraction through
the known angles of
structures 314.
[00115] As seen in FIG. 6E, conical diffusers 316 can resemble
random, rounded
"bubbles" on top of, and merged with, the underlying reference surface. The
random distribution of the
"bubbles" imparts diffusion to light passing through that can be characterized
as a cone of output light
for every beam of input light. Size of the "bubbles" and angles formed where
they adjoin, can be used
to vary the size of the dispersion cone for light passing therethrough. Thus,
microstructure sizes can
vary and an angle subtended by a dispersion cone of light passing therethrough
can be predicted from
the sizes and actual angles formed by the structures. Useful angles of
dispersion cones for conical
diffusers herein are often in the range of twenty to forty degrees.
[00116] FIG. 7 schematically illustrates, in a perspective exploded
view, a luminaire 400
in the form of a panel light assembly, having an electronics assembly 410, a
back plate 420, an optional
reflector 430, light sources 440, an edge-lit, planar light guide 450 and an
exemplary optical sheet 300(2)
having a combination of prismatic lenses and diffusers. Luminaire 400 may
include a housing 460 to
provide mechanical support for the components of luminaire 400; housing 460
forms a light output
aperture 470 through which luminaire 400 is configured to emit light 480.
Although FIG. 7 is not drawn to
any particular scale, optical sheet 300(2) is an example of a rectangular
optical sheet.
[00117] Light sources 440, light guide 250, optional reflector 430
and optical sheet
300(2) depicted in FIG. 7 may be referred to as an optical subassembly 425(1).
In the illustrated
embodiment, luminaire 400 and optical subassembly 425(1) include LEDs as light
sources 440. Light
sources 440 may be arranged within one or more sides of housing 460, and
configured to emit light into
38
Date Recue/Date Received 2020-08-05
light guide 450. Light guide 450 may have micro-structures sometimes called
"extraction features"
herein, that produce different regions of light with controlled intensities,
by disrupting total internal
reflection of light 480 within light guide 450 (see FIG. 8A). For example,
density or shape of the
extraction features can change from area to area of light guide 450, in order
to affect the net amount,
average direction, and/or directional or diffuse quality of light extracted
thereby. Together, light
sources 440 and light guide 450 act as a backlight apparatus to emit light
toward output aperture 470,
but other types of backlight apparatus (e.g., using downwardly-emitting light
sources such as arrays of
LEDs, fluorescent and/or incandescent lighting, or even natural light) are
possible (see FIG. 88).
[00118]
Optional reflector 430 may be used to capture any light that is scattered out
of
light guide 450 away from the light output direction and redirect that light
toward output aperture 470.
Reflector 430 may also have one or more patterns thereon, to further affect
the amount, average
direction, and directional or diffuse quality of light reflected therefrom.
For example, when present,
reflector 430 may have some spatial areas of specular reflection and other
spatial areas of diffuse
reflection, and the diffusion provided in such areas can vary. Areas of
specular reflection will cause light
extracted from the light guide to reflect back from the reflector at its angle
of incidence. Depending on
the type of extraction feature that directs some light toward reflector 430
(see FIG. 8A) and because
light guide 450 is typically lit from the edges, this angle may be low in
reference to the surface of the
light guide. For portions of a reflector 430 that have roughening, diffuse
substances applied, and/or the
like, there can be more scattering of light into both higher and lower angles.
Patterning of reflectors
430 with contrasting areas of diffuse and specular reflection can be used to
create areas of light contrast
in conjunction with a light guide 450, and can be used in conjunction with
optical sheets 300 herein to
create and/or enhance contrast and the visual impression of 3D effects. Other
embodiments of
luminaires 400 and/or optical subassemblies 425 may not utilize a reflector
430 (see, e.g., FIG. 88).
39
Date Recue/Date Received 2020-08-05
[00119] In the orientations of FIGS. 7, 8A and 8B, the upward
direction is toward the
"back" of the light assembly and the downward direction is the "front," that
is, the back-to-front direction is
an output light direction 0 for the luminaire. More specifically, a direction
from the backlight apparatus
toward an optical sheet 300 is defined as output light direction 0. Housing
460 can be used to support
and stabilize the elements shown with respect to one another, and further
mechanical components,
mounting hardware, and the like, may be present when luminaire 400 is fully
assembled. Typically,
luminaire 400 will include a back plate 420; an electronics assembly 410 can
include AC/DC and voltage
converters, drivers, wireless interface gear and the like, and can be mounted
on back plate 420. The light is
emitted from light sources 440 (which, again, can be but are not limited to
LEDs) into light guide 450.
Light guide 450 distributes the emitted light over the full surface of
luminaire 400, that is, across optical
sheet 300(2) enroute to output aperture 470. Light extraction features and
reflector 430 (see FIG. 8)
scatter the emitted light out of light guide 450 toward optical sheet 300(2).
Light redirecting elements
of optical sheet 300(2), such as the elliptical diffusers, conical diffusers
and/or lenses discussed above
(see FIGS. 6A through 6E) modify light 480 as it leaves optical sheet 300(2)'s
outer surface, resulting for
example in collimated, redirected and/or diffuse light leaving luminaire 400.
The distributions and
characteristics of the light redirecting elements create a 3D visual effect of
depth and/or other patterns
of light emission. An optional cover sheet or plate (e.g., a clear plastic or
glass plate, not shown) may also
be installed to protect the diffuser and other components.
[00120] Exemplary materials for light guide 450 and/or optical
sheets 300 are light
transmissive, and include plastics such as PMMA (polymethylmethacrylate),
other acrylics,
polycarbonates, polystyrene, thermoplastics, and/or blends of these plastics,
elastomers such as
silicone, and glasses. Optional reflector 430, when present, may be a separate
component, or may be a
reflective surface applied or adhered to a back side of the light guide 450.
Date Recue/Date Received 2020-08-05
[00121] With backside illumination, whether from light sources 440
and a light guide
450, or from a different backlight apparatus behind optical sheet 300,
different portions of a 3D pattern
can be configured to cause light 480 to come out at different angles (e.g.,
elliptically, conically,
collimated or asymmetrically) for different areas of the pattern, these
typically generate a visual
impression of patterned areas of contrast. Furthermore, when a viewer changes
viewing angle from the
surface, the areas of contrast (e.g., bright vs dark areas) can change,
because of the change in viewing
angle in relationship to the local emitting angle. This changing contrast
effect allows for areas of the
pattern to change from dark to bright in relationship to each other and is
strongly associated in the
human mind with a 3D effect. That is, from experience in viewing similar
changes in light with respect to
change in viewing angle, a human viewer will generally assume that they are
looking at a 3D surface,
unless they take the time to look closely and figure out that the pattern is
being emitted from a two-
dimensional object. Alternatively, when the backlight apparatus is turned off,
the luminaire surface is
no longer emitting light, but ambient light can fall on the outer surface of
optical sheet 300. In this case,
the viewer still sees the reflection of this ambient light off of the surface;
the reflected light is also
affected by the optical microstructures in the reciprocal manner of the
transmitted light, thus again
providing surface patterns of contrast that change when the viewing angle
changes. Because of this, in
this case also, the surface will be perceived by a human viewer as 3D. The use
of a reflector 430 behind
a light guide, in edge-lit designs, can enhance the reflected light even when
the luminaire is in the "off"
state, enhancing the 3D impression.
[00122] FIG. 8A schematically illustrates, in a cross-sectional
view, optical structures of
optical subassembly 425(1) of FIG. 7, including for example one LED (or other)
light source 440, optional
reflector 430, light guide 450, and optical sheet 300(2) having a combination
of prismatic lens and
elliptical diffusers. Light source 440 emits light 480 into light guide 450,
which substantially contains
41
Date Recue/Date Received 2020-08-05
light 480 through total internal reflection, except when light 480 interacts
with extraction features 455.
When scattered out of the total internal condition, light 480 may exit light
guide 450 directly (because it
is scattered into an angle that exceeds the total internal reflection
condition) or may reflect from
reflector 430 before it passes back through, and exits, light guide 450. After
leaving light guide 450 in
direction 0, light 480 passes through optical sheet 300(2) where it may be
redirected by elliptical
diffusers 312 (especially in transverse direction T), conical diffusers 316,
prismatic lens structures 314,
and/or others as described above.
[00123] FIG. 8B schematically illustrates, in a cross-sectional
view, optical structures of
an alternate optical subassembly 425(2), which includes one or more light
sources 440, and optical sheet
300(2). Light sources 440 may be any single type or combination of light
sources, e.g., LEDs,
incandescent, fluorescent and/or other light emitters. Although multiple light
sources 440 are shown in
FIG. 8B, it is intended that any number of light sources 440 may be included.
Light source(s) 440 emit
light 480 directly toward optical sheet 300(2), where it may be redirected by
elliptical diffusers 312
(especially in transverse direction T), conical diffusers 316, prismatic lens
structures 314, and/or others
as described above. Optical subassembly 425(2) may be useful for luminaires
with different
requirements than luminaire 400 (FIG. 7) due to cost, quality of light from
specific light source(s) 440, or
other criteria.
[00124] FIG. 9 schematically illustrates, in a cross-sectional view,
another exemplary
optical sheet 300(3) that has a combination of prismatic lenses and various
diffusers on both an interior
surface 302 and an outer surface 304 thereof. In this exemplary embodiment,
the top-to-bottom
direction in the orientation of FIG. 9 is direction 0. Interior side or
surface 302 of optical sheet 300(3) is
configured with prismatic lens structures 314 and opposing surface 304 is
configured with diffusers, or a
combination of diffusers and prismatic lenses. For example, the interior
surface may be configured with
42
Date Recue/Date Received 2020-08-05
prismatic lenses to produce collimated light from a light source, that is then
diffused by the diffusers
and/or lenses on the outer surface. The diffusion provided by the diffusers
and/or lenses on the outer
surface may be slight or severe, and may be omnidirectional (e.g., as provided
by conical diffusers) or
directional (e.g., as provided by elliptical diffusers, which diffuse light
more in one direction than
another). The pattern of light redirecting elements on surface 302 can be
registered, during
manufacture of optical sheet 300(3), to the pattern on surface 304 to provide
specific light redirection
effects.
[00125]
FIG. 10 shows a front view of an exemplary optical sheet 300(4) that produces
a
3D "picture frame" effect. FIG. 11 shows a front perspective view of optical
sheet 300(4), and FIG. 12
shows a side perspective view of optical sheet 300(4). The FIGS. 11 and 12
views, in combination with
that of FIG. 10, demonstrate that the optical sheet design is actually flat,
even though the design has the
visual effect of depth. The picture frame effect is achieved by having
elliptical diffusers 312 in adjacent
spatial regions 310(5), 310(6), 310(7) and 310(8a) that resemble mitered frame
sections, at different
angular orientations with respect to one another. For example, in this
embodiment, each spatial region
310 (any of 310(5), 310(6), 310(7), 310(8a) ) has elliptical diffuser 312 with
predominant orientations
that are rotated 90 degrees with respect to its adjacent spatial regions 310.
This causes each spatial
region 310 to form a contrast with the adjacent spatial region 310 from all
viewing angles; at the same
time, different ones of spatial regions 306 will be light or dark depending on
viewing angle. As discussed
above, spatial regions 310(5), 310(6), 310(7) and 310(8a) may be said herein
to form a "square" or an
"outer square," despite those spatial regions not extending through the center
of the square. In a
central spatial region 330(2) (sometimes called a central square, or inner
square, herein) conical
diffusers 316 are used to give a uniform look over a wide viewing angle, but
provide contrast to the
outer spatial regions 310 as viewing angle changes. Between the outer square
formed by spatial regions
43
Date Recue/Date Received 2020-08-05
310, and the inner square spatial region 330(2), is a spatial region 320(2)
that includes a prismatic
structure with varying prism angles. (Not all segments of spatial region
320(2) are labeled in FIGS. 10-12
for clarity of illustration.) In this embodiment, varying angles of prismatic
lens structures 314 (see FIGS.
6A, 6D) across the width of spatial region 320(2) creates a linear Fresnel
lens that creates the
appearance of a concave or convex lens cylinder. The use of this type of
Fresnel lens for spatial region
320(2) creates a visual impression of rounded depth and a bezel effect, adding
further to the 3D
appearance of the frame.
[00126]
FIGS. 13 and 14 are photographs of exemplary optical sheets 300(5), 300(6)
respectively, that illustrate the visual difference of including or not
including a prismatic lens region
between a central region and outer spatial regions. Optical sheet 300(5),
shown in FIG. 13, does not
have a prismatic lens spatial region between the inner and outer frames, and
consequently has a
relatively "flat" visual appearance. Optical sheet 300(6), shown in FIG. 14,
has a prismatic lens
perimeter between the inner and outer frames, providing a visual appearance
that much more strongly
suggests a 3D surface, despite the fact that the optical sheet is essentially
flat (that is, flat except for
<1000 micron surface features). For example, the visual appearance provided by
the combination of
features discussed above may provide a visual impression of portions of the
optical sheet being at
angles, with respect to one another, in or out of the plane of the optical
sheet. These angles, subtended
over the length of the corresponding shapes, will be interpreted by the mind
of the viewer as 3D surface
relief on the order of the size of the shapes. That is, when the shapes are
inches wide or long, the 3D
surface relief may appear to be on the order of inches; in larger
installations, when the shapes are feet
wide or long, the 3D surface relief may appear to be on the order of feet. The
3D surface relief may be
perceived as "depth," e.g., appearing to recede from the plane of the optical
sheet, or "height," e.g.,
appearing to extend toward the viewer from the plane of the optical sheet.
44
Date Recue/Date Received 2020-08-05
[00127] The prismatic elements can be Fresnel or straight prismatic
structures. In this
sense, Fresnel denotes having changing prism angles to create a lens with a
diameter/focal point, while
straight prismatic structures may be linear prisms with a repeating fixed
angle. Both the Fresnel and
prismatic elements can be used to create greater contrast when placed next to
diffuser structures.
Fresnel structures can impart a round or curved image, based on the associated
focal point of the lens.
Prismatic elements can cause collimation and/or redirection of the transmitted
light into particular
angles, and provide enhanced contrast change vs viewing angle. Asymmetric
prisms can cause
asymmetric bending of the transmitted light and asymmetric contrast.
Contrasting prismatic elements
with diffuser elements can be used to create a "forced perspective," where the
design itself creates a 3D
impression. A basic example is the drawing of a train track moving out to the
horizon using two lines; by
varying angles of the design elements, a sense of depth can be created. The
prismatic structures or
oriented diffuser structures can be overlaid on a pattern to create a forced
perspective, and ultimately
enhance the resulting 3D look.
[00128] FIGS. 15 and 16 illustrate a luminaire having an exemplary
multi-panel frame 3D
optical sheet 300(6) that provides a visual impression of four 3D panels, each
of which has a picture
frame design. The fixture includes an edge-lit light guide design constructed
similarly to luminaire 400,
as illustrated in FIGS. 7 and 8A. The "quad" design of FIGS. 15 and 16 takes
the picture frame from FIG.
13 and repeats it in each of 4 quadrants; that is, in a two row, two column
layout. Thus, the outer
spatial regions of each picture frame include elliptical diffusers, with their
predominant spatial
orientations rotated in adjacent spatial regions around each frame, and a
central region with conical
diffusers, again as illustrated in FIGS. 7 and 8A. An optional prismatic lens
perimeter is included
between the inner square and outer squares of each picture frame.
Date Recue/Date Received 2020-08-05
[00129] FIGS. 17, 18 and 19 schematically illustrate a luminaire 500
that includes a
relatively simple, recessed, 3D square frame design provided by an optical
sheet 300(7). FIG. 17 is a side
elevation of the luminaire; FIG. 18 is a bottom (e.g., upwardly-looking) plan
view of luminaire 500 at the
same scale as FIG. 17; and FIG. 19 is a schematic illustration of the optical
sheet within luminaire 500,
enlarged relative to the views of FIGS. 17 and 18.
[00130] In FIG. 17, luminaire 500 is shown as having a housing 560
and a trim ring 565.
Certain dimensions of luminaire 500 are indicated as a trim ring width WTR, a
housing width WH, a trim
ring ridge width W
¨ TRR, a fixture total height HF, a housing height HH, and a trim ring height
FITR. In a
particular embodiment, luminaire 500 can be mounted within a 6 inch square
recess or hole in a ceiling
material (e.g., drywall or ceiling tile). In this embodiment, NNTR is about
6.7 inches (to provide coverage
around the bottom of the hole or recess in which luminaire 500 mounts); WH is
about 5.9 inches (to fit
within the 6 inch square recess or hole); W
¨ TRR is about 4.1 inches; HF is about 1.2 inches, HH is about 0.5
inches; and FITR is about 0.2 inches. Housing 560 has width WH and height HH,
and contains the lighting
system of luminaire 500 (e.g., as illustrated in FIGS. 7-9). Optional, spring
loaded arms 570 may be
coupled with housing 560 in order to support it within a ceiling. Trim ring
565 is added to the bottom of
housing 560 in order to provide a finished look (the hole or recess in the
ceiling will usually be a bit
larger than housing 560, and trim ring 565 will cover the gap between the
ceiling material edge and
housing 560).
[00131] FIG. 18 indicates an trim ring inner opening width as W
¨ TRI, and a trim ring length
LTR that, in the illustrated embodiment, is equal to NNTR (that is, luminaire
500 is square in plan view,
except for spring loaded arms 570, which will be hidden above the ceiling
material). As discussed above,
the square shape and fourfold symmetry of luminaire 500 and optical sheet
300(7) are exemplary only.
Similar luminaires are contemplated which may be rectangular in plain view,
with optical sheets having
46
Date Recue/Date Received 2020-08-05
asymmetric shapes, forming for example borders that have different top and
bottom widths than left
and right widths, and the like.
[00132]
FIG. 19 illustrates various features of the optical sheet 300(7) of luminaire
500,
that provide luminaire 500 with an appearance of 3D depth from beneath,
although luminaire 500 is
relatively flat and optical sheet 300(7) is very flat. The design provided by
the illustrated optical sheet
300(7) is that of a "picture frame" similar to those shown in FIGS. 5, 10-12,
14, and 15-16, albeit with
different proportions, and the single picture frame being one of the four
frames of the FIGS. 15, 16
design. A central spatial region (or central/inner rectangle or square) 330(3)
is populated with conical
diffusers 316 (see FIGS. 6A and 6C) that may provide a dispersion cone of
about 30 degrees to light
passing therethrough. A small frame-like area formed of spatial regions
320(3), 320(4), 320(5), and
320(6) surrounding spatial region 330(3) may be present to provide a visual
boundary between inner
square spatial region 330(3) and the outer spatial regions having elliptical
diffusers, that are discussed
below. Spatial regions 320(3), 320(4), 320(5), and 320(6) surrounding spatial
region 330(3) may include
prismatic features to accent this visual boundary, similar to the case
illustrated in FIG. 14. Two
successively larger frame areas, composed of spatial regions 310(9), 310(10),
310(11), 310(12), 310(13),
310(14), 310(14) and 310(16), located outside of spatial region 330(3) and the
frame-like area, include
elliptical diffusers 312 (not labeled in FIG. 19, see FIGS. 6A and 6C). The
elliptical diffusers 312 in these
regions alternate in predominant orientation, both in sequence going around
optical sheet 300(7), and
from inward to outward relative to the edges of optical sheet 300(7) (for
example, orientation of
elliptical diffusers 312 is top-to-bottom in spatial region 310(16), but left-
to-right in immediately
adjacent spatial regions 310(12), 310((13) and 310((15), as shown).
Orientation of the diffusers within
each area is shown by a double-headed arrow in FIG. 19. The changes in
predominant orientation cause
light redirection by optical sheet 300(7) to be significantly different in
adjacent regions. This alternating
47
Date Recue/Date Received 2020-08-05
orientation provides a visual impression of 3D depth. The effect also applies,
to some degree, to light
reflected from optical sheet 300(7) when luminaire 500 is turned off. That is,
when ambient room light
reflects from the optical sheet the directions of the elliptical diffusers
will generate a different glint from
one another, and that glint will vary with respect to a viewer's position, so
as to generate a visual
impression of 3D depth even when the luminaire is turned off. A rectangular
"bleed line" 319(1) is also
designated, this is not a physical feature but corresponds to a boundary
outside of which optical sheet
300(7) is located behind the inner portion of trim ring 565, when installed.
That is, bleed line 319(1) has
both width and height equal to WTRI, indicated in FIGS. 17 and 18.
[00133] FIGS. 20, 21 and 22 schematically illustrate a luminaire 600
that includes a more
complex square frame design (than that illustrated in FIGS. 17, 18. 19) which
is provided by an optical
sheet 300(8). FIG. 20 is a side elevation of luminaire 600; FIG. 21 is a
bottom (e.g., upwardly-looking)
plan view of luminaire 600 at the same scale as FIG. 20; and FIG. 22 is a
schematic illustration of the
optical sheet within luminaire 600, enlarged relative to the views of FIGS. 20
and 21. The mechanical
components of luminaire 600 illustrated in FIGS. 20, 21 and 22 are identical
to those illustrated in FIGS.
17, 18 and 19; only the optical sheet used with luminaire 600 is different.
Therefore dimensions WTR,
WH, WTRR, HF, HH, HTR, WTRI, and LTR have the same meanings for luminaire 600
as for luminaire 500 (FIGS.
17, 18, 19).
[00134] Optical sheet 300(8) schematically illustrated in FIG. 22 is
similar to optical sheet
300(7), FIG. 19, with some key differences. Optical sheet 300(8) remains
square, with an innermost
spatial region 330(4) providing 30 degree diffusion, and an outer area that is
divided into mitered
quadrants that form a frame region. The innermost spatial region 330(4) is
surrounded by a narrow
frame-like area formed by several spatial regions 320, which may include
prismatic features to accent
this visual boundary. (Note, in FIG. 22, the many individual elements of
similar type are not necessarily
48
Date Recue/Date Received 2020-08-05
labeled with numerals in parentheses, for clarity of illustration.) The
outermost area has spatial regions
310 with elliptical diffusers. Elliptical orientation of each quadrant is
again labeled in FIG. 22 with
double headed arrows, and orientation of adjacent spatial regions in the
outermost areas are rotated by
ninety degrees relative to their neighbors at each corner. An unmarked bleed
line 319(2) is also shown
within the outermost area, indicating the area that will be visible from below
within the trim ring (e.g.,
having dimensions of W
- TRI in each direction).
[00135] However, in optical sheet 300(8), the outermost area spatial
regions 310 are
narrower than their counterparts in optical sheet 300(7), and the large area
between the outermost
area and the small, frame-like area is divided into several mitered bands
(e.g., frame regions) formed of
additional spatial regions 310 with elliptical diffusers, separated by small
continuous bands 317 with
conical diffusers. Each spatial region of the several mitered bands has the
same elliptical orientation as
those segments that run parallel to it, and in each quadrant of the frame
layout, this orientation is
rotated 90 degrees with respect to the elliptical orientation of the outermost
spatial region 310 of that
quadrant. There is also a wide, conical diffuser spatial region 318 between
the innermost mitered band
and the small, frame-like area.
[00136] Viewed from below, the layout of optical sheet 300(8)
creates a 3D impression
of "height" extending from the surface of luminaire 600 at the level of the
trim ring 665, receding
"upwards" through the several mitered bands, until it reaches a "ceiling"
level at conical diffuser spatial
region 318 between the innermost mitered band and the small, frame-like area
(spatial regions 320,
330(4) ). The small, frame-like area and the 30 degree conical diffuser area
at the center then provide
the appearance of a feature that is either suspended "below" the "ceiling"
level of spatial region 318, or
extends further "above" it. The words in quotation marks here signify that
these appearances are only
illusory, since the optical sheet that generates the 3D appearance is in fact
flat (give or take normal
49
Date Recue/Date Received 2020-08-05
manufacturing tolerances and the height of the diffusers themselves, <= 1000
microns from a reference
height of the sheet).
[00137] FIGS. 23, 24 and 25 schematically illustrate a luminaire 700
that includes a
simplified circular design provided by an optical sheet 300(9). FIG. 23 is a
side elevation of luminaire
700; FIG. 24 is a top (e.g., downwardly-looking) plan view of luminaire 700 at
the same scale as FIG. 23;
and FIG. 25 is a schematic illustration of optical sheet 300(9) within
luminaire 700, enlarged relative to
the views of FIGS. 23 and 24.
[00138] FIG. 23 indicates certain dimensions of luminaire 700 as a
trim ring diameter
DTR, a housing diameter DH, a trim ring inner opening width as arm, a fixture
total height HF, and a
housing height HH. In a particular embodiment, luminaire 700 can be mounted
within a 6 inch round
recess or hole in a ceiling material (e.g., drywall or ceiling tile). In this
embodiment, DTR is about 6.7
inches (to provide coverage around the bottom of the hole or recess in which
luminaire 700 mounts); DH
is about 5.9 inches (to fit within the 6 inch square recess or hole); HF is
about 1.1 inches; and HH is about
0.5 inches. A housing of the luminaire, having diameter DH and height HH,
contains the lighting system
of luminaire 700 (e.g., as illustrated in FIGS. 7-9, but in a round format).
Spring loaded arms may be
coupled with this housing in order to support it within the ceiling material.
Luminaire 700 is round in
the bottom plan view of FIG. 24, except for the spring loaded arms, which will
be hidden above the
ceiling material. A trim ring 765 is added to the bottom of the housing in
order to provide a finished
look (the hole or recess will usually be a bit larger than the housing, and
the trim ring will cover the gap
between the ceiling material edge and the housing).
[00139] FIG. 25 illustrates various features of the optical sheet
300(9) of luminaire 700,
that provide luminaire 700 with an appearance of 3D depth from beneath,
although luminaire 700 is
relatively flat and optical sheet 300(9) is very flat. The design provided by
optical sheet 300(9) is that of
Date Recue/Date Received 2020-08-05
a "donut" that appears to have a receding surface at different diameters
within the viewable area. An
inner spatial region 310 is populated with elliptical diffusers that are
oriented in a predominant
direction, shown as horizontal in the orientation of FIG. 25. A "donut lens"
722 surrounds the inner
region. Donut lens 722 is a radial prismatic element having varying prism
angles, in a radial band with a
fixed width (i.e., an annulus with fixed inner and outer radius). This
provides a lens effect in a "donut"
shape, as opposed to a circular Fresnel lens that has only a single radius. An
outer area, located radially
outward of the inner area and the donut lens, includes elliptical diffusers
that are oriented at a 90
degree angle to those of the inner area. This provides a visual impression of
3D depth. The effect also
applies, to some degree, to light reflected from optical sheet 300(9). That
is, when ambient room light
reflects from optical sheet 300(9), the directions of the elliptical diffusers
will generate a different glint
from one another, and that glint will vary with respect to a viewer's
position, so as to generate a visual
impression of 3D depth even when luminaire 700 is turned off, that is, the
light redirecting elements
provide effects in both transmitted and reflected light. A round "bleed line"
319(3) is designated, this is
not a physical feature but corresponds to a boundary outside of which optical
sheet 300(9) is located
behind the inner portion of the trim ring 765, when installed. That is, bleed
line 319(3) has diameter equal
to DTRI, as indicated in FIG. 23.
[00140]
FIGS. 26, 27 and 28 schematically illustrate a luminaire 800 that includes a
more
complex round frame design (than that illustrated in FIGS. 23, 24, 25) which
is provided by an optical
sheet 300(10). FIG. 26 is a side elevation of luminaire 800; FIG. 27 is a top
(e.g., downwardly-looking)
plan view of luminaire 800 at the same scale as FIG. 26; and FIG. 28 is a
schematic illustration of optical
sheet 300(10) within luminaire 800, enlarged relative to the views of FIGS. 26
and 27. The mechanical
components of luminaire 800 illustrated in FIGS. 26, 27 and 28 are identical
to those illustrated in FIGS.
51
Date Recue/Date Received 2020-08-05
23, 24 and 25; only optical sheet 300(10) used with luminaire 800 is
different. Therefore dimensions
am, DH, arm, HH, and HF have the same meanings for luminaire 800 as for
luminaire 700.
[00141] Optical sheet 300(10), as schematically illustrated in FIG.
28, is similar to optical
sheet 300(9), FIG. 25, with some key differences. Optical sheet 300(10)
remains round, with an
outermost spatial region 310(19) having elliptical diffusers, and within
spatial region 310(19), an
unmarked bleed line 319(4), indicating the area that will be visible from
below, within the trim ring 865
(e.g., having a diameter of n 1 However, in FIG. 28, the innermost area
includes a central region 823
_TRG=
formed as a Fresnel lens. Central region 823 has a focal distance that is
great enough that it does not
focus light from luminaire 800 that projects through it, since the light
source of luminaire 800 is an area
source that is too close to the surface, but Fresnel lens 823 may give optical
sheet 300(10) an either
convex or concave depth appearance. For example, a Fresnel lens 823 with a 2"
focal point may appear
to be a 2" deep or proud lens, whereas a 4" focal point Fresnel lens 823 will
seem to have less depth
when cut down to a 2 inch diameter. Between Fresnel lens 823 and spatial
region 310(19) are annular
spatial regions 310(20), 310((21) and 310((22) of elliptical diffusers, with
the elliptical orientation of each
annulus rotated by ninety degrees relative to its neighbors, and donut lens
sections 822(1), 822(2),
822(3) between each pair of elliptical diffuser spatial regions 310.
[00142] It will be appreciated by those skilled in the art that the
widths and lengths
described above can be modified to provide differently sized luminaires, but
the heights need not scale
with the widths, due to the use of light pipe and optical sheet technology
described above. Thus,
luminaires that are very large in area can be made with similar heights as
those described above, but
much larger widths/lengths/diameters.
[00143] The foregoing is provided for purposes of illustrating,
explaining, and describing
embodiments of the present invention. Further combinations, variations,
modifications and adaptations
52
Date Recue/Date Received 2020-08-05
to these embodiments will be apparent to those skilled in the art and may be
made without departing
from the scope or spirit of the invention. Different arrangements of the
components depicted in
drawings or described above, as well as components and steps not shown or
described, are possible.
Similarly, some features and subcombinations are useful and may be employed
without reference to
other features and subcombinations. Specific embodiments, features and
elements described herein
may be modified, and/or combined in any suitable manner. Embodiments of the
invention have been
described for illustrative and not restrictive purposes, and alternative
embodiments will become
apparent to readers of this patent. Accordingly, the present invention is not
limited to the
embodiments described above or depicted in drawings, and various embodiments
and modifications
can be made without departing from the scope of the claims below, and their
equivalents.
53
Date Recue/Date Received 2020-08-05
