The present invention relates to lighting, and more specifically, to a luminaire for lighting.
Conventional downward-facing luminaires are well known, frequently stylish though sometimes merely boringly functional, and produce light to which people work, play, live, and want. For office lighting, a common type of luminaire is known as a “troffer”, in which light from an elongated fluorescent bulb is directed upward toward an inverted trough having a diffuse reflecting surface. The diffusely reflected light from the inverted trough is directed downward, toward a work surface in the office. These troffers are often sold as generally rectangular fixtures that fit into a ceiling grid, so that they may be positioned as needed during setup of the office.
With the proliferation of high power solid state light sources that increasingly cost less and less, luminaires that use solid state light sources instead of conventional light sources are becoming more and more common. One such luminaire is a troffer-style fixture disclosed in U.S. Published Patent Application No. 2012/0051041, entitled “Troffer-style fixture” and published on Mar. 1, 2012. The '041 application discloses a troffer-type luminaire with solid state light sources arranged in one or two stripes, down the center of the fixture, directing light upward. Directly beneath the stripe or stripes is a heat sink, which dissipates heat from the solid state light sources.
Conventional solid state light source-based troffer-type luminaires, such as described in regards to the '041 application above, suffers from a variety of deficiencies, namely that the heat sink located beneath the stripe or stripes of solid state light sources is opaque. Thus, the heat sink blocks some light radiated from the fixture, which results in a dark stripe through the center of the fixture and bright regions on either side of the dark stripe. This dark stripe is not aesthetically pleasing. Further, such a dark stripe is not found in troffer-style luminaires utilizing conventional light sources (e.g., fluorescent lamps), which the solid state light source-based luminaires seek to replace. These factors combined may lessen the acceptance and use of such luminaires.
Embodiments of the present invention provide a luminaire including solid state light sources, which may take the shape and form factor of a conventional troffer-type luminaire, and which provides light that extends fully across a viewing window of the luminaire, without a dark stripe down the center. Such a luminaire includes a downward-facing housing with a diffusely reflecting top side. The housing also includes at least one, and sometimes a pair of, specularly reflecting lateral side(s) extending generally downward from a respective edge of the top side. The housing also includes at least one light source mounting surface extending laterally inward from a respective bottom edge of the respective lateral side. A downward protrusion may be disposed in the center of the top side, which extends generally parallel to the lateral sides. A plurality of solid state light sources is disposed along the light source mounting surface(s) proximate to the lateral side(s). The solid state light sources emit light generally upward toward the top side. The lateral sides reflect light from the solid state light sources upward toward the top side. The top side then diffusely reflects the light downward, achieving a uniform light distribution without the presence of a dark stripe.
In an embodiment, there is provided a luminaire housing. The luminaire housing includes: a diffusely reflecting top side, the diffusely reflecting top side having an edge; at least one specularly reflecting lateral side extending generally downward from a respective edge of the diffusely reflecting top side; and at least one light source mounting surface extending laterally inward from a respective bottom edge of the respective at least one specularly reflecting lateral side.
In a related embodiment, the at least one specularly reflecting lateral side may include a pair of specularly reflecting lateral sides, and the at least one light source mounting surface may include a pair of horizontal light source mounting surfaces, each horizontal light source mounting surface extending across two opposing lateral edges of the luminaire housing. In a further related embodiment, for vertical cross-sectional slices of the luminaire housing taken perpendicular to the opposing lateral edges, the cross-sectional slices may be the same for all points along the opposing lateral edges. In a further related embodiment, the luminaire housing may be elongated along a direction generally parallel to the opposing lateral edges.
In another related embodiment, the diffusely reflecting top side may include a downward protrusion located at a center of the diffusely reflecting top side. In still another related embodiment, the diffusely reflecting top side, the at least one specularly reflecting lateral side, and the at least one light source mounting surface may be formed together such that at least one specularly reflecting lateral side, viewed from below the luminaire housing, shows a reflection of the diffusely reflecting top side. In yet another related embodiment, the luminaire housing may have a generally rectangular footprint, and the luminaire housing may include four reflecting lateral sides and four light source mounting surfaces, each extending across a side of the rectangular footprint. In still yet another related embodiment, the luminaire housing may have a generally round of freeform footprint, and the luminaire housing may include at least one reflecting lateral side following the generally round of freeform footprint of the luminaire housing and being generally perpendicular to the diffusely reflecting top side of the luminaire housing.
In yet still another related embodiment, the luminaire housing may further include a plurality of solid state light sources disposed along the at least one light source mounting surface, the plurality of solid state light sources emitting light generally upward toward the diffusely reflecting top side. In a further related embodiment, the solid state light sources in the plurality of solid state light sources may be spaced so as to produce a generally uniform illumination of light at the diffusely reflecting top side. In another further related embodiment, the plurality of solid state light sources may be grouped into a plurality of clusters, each cluster in the plurality of clusters having a first solid state light source that emits light of a first wavelength and a second solid state light source that emits light of a second wavelength, wherein the first wavelength and the second wavelength may be distinct. In a further related embodiment, the plurality of clusters may be spaced so as to produce substantially white light at the diffusely reflecting top side.
In yet still another related embodiment, the at least one specularly reflecting lateral side may include a plurality of specularly reflecting lateral sides, and the diffusely reflecting top side may be perpendicular to each specularly reflecting lateral side in the plurality of specularly reflecting lateral sides at the intersection of the diffusely reflecting top side and the respective specularly reflecting lateral side.
In another embodiment, there is provided a luminaire. The luminaire includes: a diffusely reflecting top side having opposing lateral edges and a center; a pair of specularly reflecting lateral sides extending generally downward from the opposing lateral edges of the top side, each specularly reflecting lateral side having a respective bottom edge; a downward protrusion in the center of the top side, the downward protrusion extending generally parallel to the pair of specularly reflecting lateral sides; a pair of light source mounting surfaces extending laterally inward from the respective bottom edges of the pair of specularly reflecting lateral sides; and a plurality of solid state light sources disposed along the pair of light source mounting surfaces proximate the pair of specularly reflecting lateral sides, the plurality of solid state light sources emitting light generally upward toward the diffusely reflecting top side, the pair of specularly reflecting lateral sides reflecting light emitted from the plurality of solid state light sources upward toward the diffusely reflecting top side.
In a related embodiment, an area between the pair of light source mounting surfaces may define a downward-facing window, through which light emitted by the plurality of solid state light sources and reflected off the diffusely reflecting top side may be visible. In a further related embodiment, the window may be formed within the luminaire such that the diffusely reflecting top side is visible through the window from directly below the window. In another further related embodiment, the window may be formed within the luminaire such that the diffusely reflecting top side may be visible through the window via reflection off at least one of the specularly reflecting lateral sides in the pair of specularly reflecting lateral sides from locations offset from directly below the window. In still another further related embodiment, the window may be elongated along the a pair of specularly reflecting lateral sides.
In another related embodiment, the diffusely reflecting top side may be perpendicular to each specularly reflecting lateral side in the pair of specularly reflecting lateral sides at an intersection of the diffusely reflecting top side and the respective specularly reflecting lateral side.
The foregoing and other objects, features and advantages disclosed herein will be apparent from the following description of particular embodiments disclosed herein, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles disclosed herein.
Throughout this application, the directional terms “up”, “down”, “upward”, “downward”, “top”, “bottom”, “side”, “lateral”, “longitudinal” and the like are used to describe the absolute and relative orientations of particular elements. For example, some embodiments herein refer to a “top” side of a luminaire housing that includes a diffuse reflector and a “bottom” of a luminaire housing through which light exits the luminaire housing. In this example, “top” and “bottom” are used to indicate the typical orientations when the luminaire is installed and operational, typically mounted in a ceiling or as part of a ceiling grid. It is understood that these orientational terms are used only for convenience, and are not intended to be limiting. Thus, when a luminaire according to embodiments described herein is, for example, packaged in a box, resting on a counter, leaned up against a wall, or in various stages of assembly on an assembly line, the luminaire may be positioned in any orientation but will still have a “top” side that includes a diffuse reflector and a “bottom” through which light would exit the luminaire, were it powered and operating. In other words, the orientational terms are used for ease of description and may be used regardless of the actual orientation of the luminaire at a given point in time.
Embodiments of a luminaire are described throughout as being “downward-facing”, for ease and convenience of description, however, embodiments are not so limited. That is, a luminaire according to embodiments is useable in any orientation. The luminaire includes a housing with a diffusely reflecting top side, at least one specularly reflecting lateral side extending generally downward from a respective edge of the top side, and at least one light source mounting surface extending horizontally inward from a respective bottom edge of the respective lateral side. In some embodiments, the luminaire includes two or more reflecting lateral sides and two or more light source mounting surfaces, each extending along opposing lateral edges of the housing. In some embodiments, the top side of the housing has a downward protrusion at its center, optionally extending parallel to the lateral sides. As an advantage, the specularly reflecting lateral side(s)s may give an illusion of a light-emitting surface (i.e., the diffusely reflecting top side of the housing) that appears to extend laterally farther than it actually does.
The luminaire 100 includes a housing 1. In some embodiments, the housing 1 defines a portion of the structure of the luminaire 100, while in other embodiments, the housing 1 defines the entirety of the structure of the luminaire 100. The housing 1 includes a top side 2, having an outer surface (i.e., a surface that is visible from the top of the luminaire 100) and an inner surface (i.e., a surface is visible from the bottom of the luminaire 100). The top side 2, and in some embodiments more particularly the inner surface of the top side 2, is diffusely reflecting. The top side 2, and in some embodiments the inner surface of the top side 2, is made of one or more diffusely reflecting materials. Alternatively, in some embodiments, the top side 2, and in some embodiments the inner surface of the top side 2, is coated with one or more diffusely reflecting coatings. In other embodiments, the top side 2, and in some embodiments the inner surface of the top side 2, is partially formed of one or more diffusely reflecting materials and partially coated with one or more diffusely reflecting coatings. In some embodiments, the top side 2 is light-colored, preferably white and/or substantially white, but not so limited, so that the top side 2, and in some embodiments the inner surface of the top side 2, reflects incident light. In addition, the top side 2, and in some embodiments the inner surface of the top side 2, is roughened and/or substantially roughened, rather than smooth, so that reflected light scatters and leaves the top side 2, and in some embodiments the inner surface of the top side 2, with a randomized direction. In general, the more rough a surface, the higher the degree of randomization of light in the exiting direction from the surface. In the extreme case of a perfectly smooth surface, the perfectly smooth surface reflects specularly, where the angle of incidence equals the angle of reflection, both with respect to a surface normal. Typically, a top side 2 that was specularly reflecting would be undesirable with, for example, light emitting diodes, as the specular reflection, when viewed from below, would show certain spots as brighter than other spots. By using a diffuse reflection instead, in embodiments including light emitting diodes and other similar solid state light sources, any such bright spots are completely or largely obscured.
The top side 2 shown in
In some embodiments, such as the luminaire 200 shown in
In
Using a downward/substantially downward protrusion, as shown in
In some embodiments disclosed herein, the protrusion 6 extends generally cylindrically along a length of the top side 2. More precisely, for vertical cross-sectional slices of the top side 2 taken perpendicular to the opposing lateral sides 3 (i.e., parallel to the plane of the page in
The luminaire housing 1 also includes a pair of lateral sides 3 that are connected to the top side 2. In some embodiments, the luminaire 100 includes only a single lateral side 3. In some embodiments, more lateral sides 3 are used. At least one lateral side 3, and in some embodiments each of the pair of lateral sides 3, extend downward from the top side 2. In some embodiments, some number of the lateral sides 3 extend in a different direction in relation to the top side 2. In some embodiments, some number of the lateral sides 3 extend in more than one direction in relation to the top side 2, for example but not limited to both upward and downward. Each lateral side includes at least two surfaces, an inner surface that faces the diffusely reflecting surface of the top side 2 and an outer surface that faces in the opposite direction. At least one, and in some embodiments both, of the pair of lateral sides 3 are specularly reflecting, on at least its(their) respective inner surfaces, in contrast with the diffuse reflection of the top side 2. In some embodiments, such as shown in
A lateral side 3 (and in some embodiments, each of the pair of lateral sides 3) includes a light source mounting surface 4 attached and/or otherwise connected and/or adjacent thereto. In some embodiments, the light source mounting surface extends along the full length of the lateral side 3 to which it is attached/connected/adjacent thereto. In some embodiments, the light source mounting surface extends along only a portion of lateral side 3. In some embodiments, a plurality of light source mounting surfaces 4 are located along the lateral side 3. The plurality of light source mounting surfaces 4 may be arranged in any known way, for example but not limited to abutting, overlapping, with space in between, and any combinations thereof. As shown in
At least one light source 7 is mounted on a light source mounting surface 4. In some embodiments, the at least one light source 7 is mounted closer to the lateral side 3 nearest the light source mounting surface 4. In some embodiments, the at least one light source 7 is mounted farther away from that lateral side. In some embodiments, the at least one light source 7 is mounted centrally on the light source mounting surface 4. In some embodiments, each light source mounting surface 4 in the luminaire 100 includes at least one light source 7, as shown in
The light source 7, whether including a single light source or a plurality of light sources, emits light upward toward the top side 2 of the luminaire housing 1, where it is diffusely reflected downward out of the luminaire housing 1. Because the lateral sides 3 of the luminaire housing 1 are specularly reflecting, if one looks at the lateral sides 3 from underneath the luminaire 100, one sees a reflection of the top side 2 and the scattered light emitted by the light source 7 therefrom. Basically, the reflective lateral sides 3 give the illusion that the light-scattering top side 2 appears to extend laterally farther than it actually does, which is aesthetically pleasing.
A second aesthetic function of the specularly reflective lateral sides 3 is to hide the presence, spacing and color variation of the light source(s) 7, particularly when the light source 7 is one or more solid state light sources. If the lateral sides 3 were made with diffuse reflectors, a bright plume of light would be visible directly adjacent to each solid state light source. Spaces in between each plume would be relatively dark and any color differences (intentional or unintentional) in the light emitted by respective solid state light sources would be visible in the plumes. This aesthetic function occurs because the reflection of light from the specular surface is undetectable from below. Only when it reaches the top surface is any part of it scattered in the downward direction toward an observer. In propagating this distance, the rays of light from several solid state light sources blend together to become relatively uniform.
In some embodiments, there is an empty space between the light source mounting surfaces 4. This space may be, and in some embodiments is, defined as a downward-facing window 8. The downward-facing window 8, in some embodiments, includes a physical piece of glass and/or plastic, and in some embodiments, this physical piece is itself a diffuser and/or is coated with a diffusive material. In some embodiments, the window 8 is simply an opening, defined on at least one lateral edge by a light source mounting surface 4, and the light emitted from the luminaire 100 exits through the window 8.
Note that for an observer who looks at the lateral side 3, the observer will see a virtual image of the top side 2. The concatenation of the virtual image of the top side 2, being disposed directly adjacent to the actual top side 2, may give the desirable illusion that the top side 2 appears to extend laterally farther than it actually does.
Regarding the number of placement of light sources 7 on the light source mounting surface 4, there is a trade-off between uniformity of brightness at the top side 2, and economy in using as few light sources 7 as possible. Light emitted from a solid state light source propagates a certain distance to the top side 2. Thus, some of the peaks and valleys in the intensity pattern will be blurred out at the top side 2. In some embodiments, there is a particular threshold value for spacing of solid state light sources, beyond which the peaks and valleys become undesirably large. This threshold is easily found when simulating the design the luminaire 100, typically before any parts are built. There are several known ray-tracing programs that are commonly used to simulate the performance of a luminaire, such as the luminaire 100, and to optimize the luminaire housing 1 and light source layout and geometry. For example, the program Lucidshape is computer aided designing software for lighting design tasks, and is commercially available from the company Brandenburg GmbH, located in Paderborn, Germany. Other known computer software and/or sources may also be used.
In some embodiments, the light emitted by the luminaire 100 is white light/substantially white light. As is known in the art, white light is produced from solid state light sources in at least two ways. A first way involves the use of a yellow phosphor in combination with blue light from the solid state light source(s). In embodiments using such a phosphor and solid state light sources, the phosphor is located, for example, on the top side 2 of the luminaire housing 1, or on the solid state light sources 7 themselves. The second way is to use a combination of two or more colors of light, emitted from corresponding solid state light sources, known as color mixing. Well-known color mixing combinations include red, green, blue, and red and green, among others. These combinations may be adjusted during production of the luminaire 100, in some embodiments, or may be adjustable after production, in some embodiments. The spacing of the solid state light sources is such that white light is seen at the top side 2 of the luminaire housing 1.
Any or all of the reflective or support surfaces of the luminaire 100 may be, and in some embodiments are, made integrally with other surfaces, or may be, and in some embodiments are, made separately and attached to other surfaces. In some embodiments, the top side 2, the lateral sides 3, and the light source mounting surfaces 4 are all be formed from the same piece of metal or plastic. In some embodiments, the specularly reflective material of the lateral sides 3 is a specular laminate on a diffuse material. In some embodiments, the top side 2 and the lateral sides 3 are made from the same material, but with a change in surface finish. Likewise, in some embodiments, the light source mounting surfaces 4 are made separately, optionally from a different material, and are attached by screws, adhesive, a snap-connection, or by any other means to respective lateral sides 3. In some embodiments, the edge formed between the top side 2 and a lateral side 3 is an actual edge between two different materials, while in some embodiments, the edge is simply a change in material or a change in layered materials, rather than a real edge between discrete parts. Regardless of which elements are made integrally and which are made separately and attached afterward, the luminaire 100 includes the luminaire housing 1 having the top side 2, the lateral sides 3 and the light source mounting surfaces 4.
Though embodiments have been described throughout as having a shape suitable for a troffer-style luminaire, other luminaire styles, such as but not limited to a suspended pendant and other indirect-lighting luminaires, are within the scope of the invention. Further, in some embodiments, the light source mounting surface may extend along all or most of a perimeter of the luminaire, rather than just along opposing sides. Further, in some embodiments, the top side of the luminaire housing may have more of an X-shaped pattern than the left-right-symmetric patterns shown above. In general, one of ordinary skill in the art will be able to simulate the performance of the more complicated top side shapes, and will be able to adjust the shape to optimize performance using known simulation software.
Unless otherwise stated, use of the word “substantially” may be construed to include a precise relationship, condition, arrangement, orientation, and/or other characteristic, and deviations thereof as understood by one of ordinary skill in the art, to the extent that such deviations do not materially affect the disclosed methods and systems.
Throughout the entirety of the present disclosure, use of the articles “a” and/or “an” and/or “the” to modify a noun may be understood to be used for convenience and to include one, or more than one, of the modified noun, unless otherwise specifically stated. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
Elements, components, modules, and/or parts thereof that are described and/or otherwise portrayed through the figures to communicate with, be associated with, and/or be based on, something else, may be understood to so communicate, be associated with, and or be based on in a direct and/or indirect manner, unless otherwise stipulated herein.
Although the methods and systems have been described relative to a specific embodiment thereof, they are not so limited. Obviously many modifications and variations may become apparent in light of the above teachings. Many additional changes in the details, materials, and arrangement of parts, herein described and illustrated, may be made by those skilled in the art.