CA3089082C - Systems and methods for stabilizing optical sheets in luminaires - Google Patents

Abstract

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.

Description

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, 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 Date Recue/Date Received 2020-08-05 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 Date Recue/Date Received 2020-08-05 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 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.

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.

Date Recue/Date Received 2020-08-05

[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.

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.

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.

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

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.

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 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 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 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 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 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 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 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 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 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.

[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.

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 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., 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 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 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 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.

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 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

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 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 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).

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 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 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 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.

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 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 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 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 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.

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 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.

Date Recue/Date Received 2020-08-05

Claims (25)

CLAIMS:

1. A luminaire, comprising:
a. at least one light source;
b. a light shaping film supported within the luminaire, wherein the light shaping film is substantially flat when supported within the luminaire and comprises a first surface and an opposing second surface and a light shaping film thickness defined between the first surface and the second surface of the light shaping film, wherein the first surface is disposed more proximate the at least one light source than the second surface so that light emitted by the at least one light source passes through the first surface and subsequently through the second surface; and c. a film stabilizer supported within the luminaire and comprising a first surface disposed adjacent the second surface of the light shaping film, an opposing second surface, and a film stabilizer thickness defined between the first surface and the second surface of the film stabilizer, wherein the film stabilizer thickness is greater than the light shaping film thickness and wherein the film stabilizer is adapted to reduce sagging of the light shaping film such that the light shaping film remains substantially flat when supported within the luminaire.

2. The luminaire of claim 1, wherein the first surface of the film stabilizer contacts the second surface of the light shaping film.

3. The luminaire of claim 1, wherein the light shaping film generates a pattern having a three-dimensional appearance despite the light shaping film being substantially flat.

4. The luminaire of claim 1, wherein the film stabilizer is adapted to diffuse light passing therethrough.

5. The luminaire of claim 4, wherein the film stabilizer is adapted to diffuse light passing therethrough between two and ten degrees.

6. The luminaire of claim 1, wherein at least one of the first surface or the second surface of the film stabilizer comprises a textured surface.

7. The luminaire of claim 1, wherein the film stabilizer comprises polymethyl methacrylate.

8. The luminaire of claim 1, wherein the film stabilizer thickness is in a range of 0.5mm to 4.0mm.

9. The luminaire of claim 1, wherein the light shaping film thickness is in a range of 0.1mm to 1.5mm.

10. The luminaire of claim 1, further comprising a light guide configured to receive light from the at least one light source through an edge of the light guide, and to emit at least a portion of the light from a light emitting surface of the light guide toward the first surface of the light shaping film.

11. The luminaire of claim 1, further comprising a housing frame adapted to support the light shaping film and the film stabilizer within the luminaire.

12. A luminaire, comprising:
a. a housing;
b. at least one light source;
c. an optical sheet supported within the housing and comprising a first surface, an opposing second surface, and an optical sheet thickness defined between the first surface and the second surface of the optical sheet, wherein:
- the first surface and the second surface are disposed substantially horizontally when the luminaire is in an installed orientation, and - the first surface is disposed more proximate the at least one light source than the second surface so that light emitted by the at least one light source passes through the first surface and subsequently through the second surface; and d. a film stabilizer supported within the housing and comprising a first surface disposed adjacent the second surface of the optical sheet, an opposing second surface, and a film stabilizer thickness defined between the first surface and the second surface of the film stabilizer, wherein the film stabilizer thickness is greater than the optical sheet thickness and wherein the film stabilizer is adapted to reduce sagging of the optical sheet such that the optical sheet remains substantially flat when supported within the housing.

13. The luminaire of claim 12, wherein the optical sheet is adapted to redirect light passing therethrough, and a degree of redirection imparted by the optical sheet is different among spatial regions of the optical sheet so as to create an image on the optical sheet.

14. The luminaire of claim 13, wherein the image appears three-dimensional despite the optical sheet being substantially flat.

15. The luminaire of claim 12, wherein the optical sheet modifies intensity of light passing therethrough, and a degree of intensity change imparted by the optical sheet is different among spatial regions of the optical sheet so as to create an image on the optical sheet.

16. The luminaire of claim 15, wherein the image appears three-dimensional despite the optical sheet being substantially flat.

17. The luminaire of claim 12, wherein the film stabilizer is adapted to diffuse light passing therethrough.

18. The luminaire of claim 12, wherein the film stabilizer comprises one of polymethyl methacrylate, polycarbonate or polyethylene.

19. The luminaire of claim 12, wherein the film stabilizer has a thickness in a range of 0.5mm to 4.0mm.

20. The luminaire of claim 12, wherein the at least one light source comprises one or more light-emitting diodes.

21. The luminaire of claim 12, wherein the at least one light source is mounted on an inner top surface of the housing so as to emit the light in a direction toward the first surface of the optical sheet.

22. The luminaire of claim 12, further comprising a light guide configured to receive light ftom the at least one light source through an edge of the light guide and to emit at least a portion of the light from a light emitting surface of the light guide toward the first surface of the optical sheet.

23. The luminaire of claim 12, further comprising a diffuser positioned between the at least one light source and the first surface of the optical sheet to diffuse light emitted by the light source prior to entry through the first surface of the optical sheet.

24. The luminaire of claim 12, wherein:
- the housing is configured for installation within and across an area of a ceiling, wherein a span length represents a distance across the area;
- the optical sheet is formed of a flexible material that only partially supports the weight of the optical sheet 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 with an absence of support at the second surface of the optical sheet; and - the film stabilizer is adapted to support the second surface of the optical sheet so that the optical sheet and the film stabilizer, together, sag less than 0.1% of the span length.

25. A portion of a luminaire comprising:
a. a frame;
b. a light shaping film supported by the frame, wherein the light shaping film is substantially flat and comprises a first surface, an opposing second surface, and a light shaping film thickness defined between the first surface and the second surface of the light shaping film;
and c. a film stabilizer supported by the luminaire and comprising a first surface, an opposing second surface, and a film stabilizer thickness defined between the first surface and the second surface of the film stabilizer, wherein the film stabilizer thickness is greater than the light shaping film thickness and wherein the film stabilizer is adapted to reduce sagging of the light shaping film such that the light shaping film remains substantially flat when supported by the frame, wherein the light shaping film and the film stabilizer are supported by the frame such that:
- the first surface of the light shaping film is adapted to be located more proximate a light source in the luminaire than the second surface of the light shaping film so that light emitted from the light source passes through the first surface of the light shaping film and subsequently through the second surface of the light shaping film such that the light shaping film generates a pattern having a three-dimensional appearance despite the light shaping film being substantially flat; and - the first surface of the film stabilizer is disposed adjacent the second surface of the light shaping film.