WO2014139183A1

WO2014139183A1 - Modular lensed troffer fixture

Info

Publication number: WO2014139183A1
Application number: PCT/CN2013/072772
Authority: WO
Inventors: Antony Paul Van De Ven; Wai Kwan Chan; Chin Wah Ho; Gauss Ho Ching So
Original assignee: Cree Hong Kong Limited
Priority date: 2013-03-15
Filing date: 2013-03-15
Publication date: 2014-09-18
Also published as: CN105190162A

Abstract

A modular lensed troffer fixture that is well-suited for use with solid state light sources. A housing provides the structural frame for a plurality of light modules arranged in an array (e.g., 2 x 2, 4 x 1). Each of the modules comprises an array of light emitters (e.g., LEDs) at the base of a reflection chamber that is defined by reflector panels. Primary optics are placed over the open end of the reflection chambers. The primary optics may comprise a diffuser and/or a polarized film. The light module array may be surrounded by a reflective pan structure. A secondary optic (e.g., a textured lens) is placed at the fixture opening to interact with the light as it is emitted from the fixture. The emitted light interacts with reflective surfaces, optics, and other components that work to diffuse and mix the light to provide a visually pleasing luminous output.

Description

MODULAR LENSED TROFFER FIXTURE

BACKGROUND OF THE INVENTION

Field of the Invention

[0001] The invention relates to troffer-style lighting fixtures, and more particularly, to troffer-style lighting fixtures utilizing lenses and/or diffusers to control light from the source.

Description of the Related Art

[0002] Troffer-style fixtures are ubiquitous in commercial office and industrial spaces throughout the world. In many instances these troffers house elongated fluorescent light bulbs that span the length of the troffer. Troffers may be mounted to or suspended from ceilings, such as being suspended by a "T-grid". Often the troffer may be recessed into the ceiling, with the back side of the troffer (i.e. troffer pan) protruding into the plenum area above the ceiling a distance of up to six inches or more. In other arrangements, elements of the troffer on the back side dissipate heat generated by the light source into the plenum where air can be circulated to facilitate the cooling mechanism. U.S. Pat. No. 5,823,663 to Bell, et al . and U.S. Pat. No. 6,210,025 to Schmidt, et al . are examples of typical troffer-style fixtures. These fixtures can require a significant amount of ceiling space to operate properly.

[0003] More recently, with the advent of the efficient solid state lighting sources, these troffers have been used with solid state light sources, such as light emitting diodes (LEDs) . LEDs are solid state devices that convert electric energy to light and generally comprise one or more active regions of semiconductor material interposed between oppositely doped semiconductor layers. When a bias is applied across the doped layers, holes and electrons are injected into the active region where they recombine to generate light. Light is produced in the active region and emitted from surfaces of the LED.

[0004] LEDs have certain characteristics that make them desirable for many lighting applications that were previously the realm of incandescent or fluorescent lights. Incandescent lights are very energy-inefficient light sources with approximately ninety percent of the electricity they consume being released as heat rather than light. Fluorescent light bulbs are more energy efficient than incandescent light bulbs by a factor of about 10, but are still relatively inefficient. LEDs by contrast, can emit the same luminous flux as incandescent and fluorescent lights using a fraction of the energy.

[0005] In addition, LEDs can have a significantly longer operational lifetime. Incandescent light bulbs have relatively short lifetimes, with some having a lifetime in the range of about 750-1000 hours. Fluorescent bulbs can also have lifetimes longer than incandescent bulbs such as in the range of approximately 10,000-20,000 hours, but provide less desirable color emission. In comparison, LEDs can have lifetimes between 50,000 and 70,000 hours. The increased efficiency and extended lifetime of LEDs is attractive to many lighting suppliers and has resulted in LED light sources being used in place of conventional lighting in many different applications. It is predicted that further improvements will result in their general acceptance in more and more lighting applications. An increase in the adoption of LEDs in place of incandescent or fluorescent lighting would result in increased lighting efficiency and significant energy saving.

[0006] LED components or lamps have been developed that comprise an array of multiple LED packages mounted to a

(PCB) , substrate or submount . The array of LED packages can comprise groups of LED packages emitting different colors, and specular reflector systems to reflect light emitted by the LED chips. Some of these LED components are arranged to produce a white light combination of the light emitted by the different LED chips.

[0007] In order to generate a desired output color, it is sometimes necessary to mix colors of light which are more easily produced using common semiconductor systems. Because of the physical arrangement of the various source elements, multicolor sources often cast shadows with color separation and provide an output with poor color uniformity. Thus, one challenge associated with multicolor light sources is good spatial color mixing over the entire range of viewing angles. One known approach to the problem of color mixing is to use a diffuser to scatter light from the various sources.

[0008] Many current luminaire designs utilize forward- facing LED components with a specular reflector disposed behind the LEDs. One design challenge associated with multi-source luminaires is blending the light from LED sources within the luminaire so that the individual sources are not visible to an observer. Heavily diffusive elements are also used to mix the color spectra from the various sources to achieve a uniform output color profile. To blend the sources and aid in color mixing, heavily diffusive exit windows have been used. However, transmission through such heavily diffusive materials causes significant optical loss.

[0009] Some recent designs have incorporated light sources or light engines utilizing an indirect lighting scheme in which the LEDs or other sources are aimed in a direction other than the intended emission direction. This may be done to encourage the light to interact with internal elements, such as diffusers, for example. One example of an indirect fixture can be found in U.S. Patent No. 7, 722, 220 to van de Ven which is commonly assigned with the present application.

[0010] There have also been recent designs that focus more on retrofitting or redesigning existing troffer- style light fixtures so that they utilize LEDs at their light source. This can allow manufacturers to use existing manufacturing capabilities to produce troffer housings for LEDs, which is thought to help in reducing overall troffer costs. In some of these fixtures, hundreds of LED packages are mounted to the surface of an existing troffer pan to essentially cover the troffer pan surface with emitters. In some of these up to 400 LED packages can be utilized. The emitters are then driven with a relatively low electrical signal in the hopes that the fixture would give the relatively even emission light fixture with no visible hot spots.

[0011] Troffer-style light fixtures are typically provided with a prismatic lens or diffuser over the troffer pan/housing opening that faces the room to be illuminated. The prismatic diffuser is included to disperse some of the light from the light source. Despite the use of hundreds of LED packages in an effort to spread the light source, these LED fixtures can still exhibit multiple emission hot spots as the light passes through the prismatic diffuser. These hot spots can be undesirable to the end user. These fixtures having hundreds of LED packages can be relatively expensive, with the bulk of the expense being the LED packages, along with the cost and complexity of mounting, interconnecting and driving the LED packages.

SUMMARY OF THE INVENTION

[0012] An embodiment of a light fixture comprises the following elements. A fixture housing has a fixture opening. An array of light modules is in the housing, each of the light modules comprising: a plurality of reflective panels defining a reflection chamber having a base and an open end; a plurality of light emitters at the base of the reflection chamber; and a primary optic proximate to the plurality of light emitters. A secondary optic spans the fixture opening.

[0013] An embodiment of a light fixture comprises the following elements. A fixture housing comprises a reflective pan structure that defines a fixture opening. An array of light modules is in the housing, each of said light modules comprising: a reflection chamber defined by at least one reflective panel; at least one light emitter in the reflection chamber; and a primary optic proximate to the at least one emitter. A secondary optic spans the fixture opening.

[0014] An embodiment of a light fixture comprises the following elements. A fixture housing has a fixture opening. An array of light modules is in the housing, each of the light modules comprising: a reflection chamber defined by at least one reflective panel; at least one light emitter in the reflection chamber; and a primary optic proximate to the at least one emitter. A driver circuit is external to the reflection chambers and between the reflective panels and the housing.

[0015] These and other aspects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings which illustrate, by way of example, embodiments of the invention .

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 shows a perspective view of a light fixture according to an embodiment of the present invention.

[0017] FIG. 2 is a perspective view of the back side of the fixture.

[0018] FIG. 3 shows several views of a fixture according to an embodiment of the present invention. FIG. 3a is a bottom view (room side); FIG. 3b is front view; FIG. 3c is a side view; and FIG. 3d is a top view (ceiling side) .

[0019] FIGs. 4a-c show several views of a fixture according to an embodiment of the present invention. FIG. 4a is a front view; FIG. 4b is a side plan view along section line A-A. ; and FIG. 4c is a detailed view of the area C.

[0020] FIG. 5a is a back view of a fixture according to an embodiment of the present invention. FIG. 5b is a side plan view along section line B-B. [0021] FIG. 6 is a block diagram of various circuit components that might be used in a driver circuit according to embodiments of the present invention.

[0022] FIG. 7 is a perspective view of the bottom of a fixture according to an embodiment of the present invention with the primary and secondary optics removed.

[0023] FIG. 8 shows a close-up perspective view of one of the light modules that may be used in fixture according to an embodiment of the present invention.

[0024] FIG. 9 is a perspective view of a fixture according to an embodiment of the present invention that is powered up and emitting light.

[0025] FIG. 10 is a perspective view of a fixture according to an embodiment of the present invention.

[0026] FIG. 11 is perspective view of a fixture according to an embodiment of the present invention.

[0027] FIG. 12 is a perspective view of a fixture according to an embodiment of the present invention.

[0028] FIG. 13 is a perspective view of a square LED downlight according to an embodiment of the present invention .

[0029] FIG. 14 shows several views of a linear fixture according to an embodiment of the present invention. FIG. 14a is top view (ceiling side); FIGs. 14b and 14e are identical end views; FIG. 14c is a side view; FIG. 14d is a bottom view (room side); FIG. 14f is a side plan view along section line A-A; FIG. 14g is a top side perspective view; and FIG. 14h is a bottom side perspective view. [0030] FIG. 15 is a perspective view of an extended linear fixture according to an embodiment of the present invention .

DETAILED DESCRIPTION OF THE INVENTION

[0031] Embodiments of the present invention provide a low cost modular lensed troffer fixture that is well-suited for use with solid state light sources. A housing provides the structural frame for a plurality of light modules arranged in an array (e.g., 2 x 2, 4 x 1) . Each of the modules comprises an array of light emitters (e.g., LEDs) at the base of a reflection chamber that is defined by reflector panels. Primary optics are placed over the open end of the reflection chambers. The primary optics may comprise a diffuser and/or a polarized film. The light module array may be surrounded by a reflective pan structure. A secondary optic (e.g., a textured lens) is placed at the fixture opening to interact with the light as it is emitted from the fixture. After it is emitted from the light emitters, the light interacts with reflective surfaces, optics, and other components that work to diffuse and mix the light to provide a visually pleasing luminous output.

[0032] It is understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. Furthermore, relative terms such as "inner", "outer", "upper", "above", "lower", "beneath", and "below", and similar terms, may be used herein to describe a relationship of one element to another. It is understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0033] Although the ordinal terms first, second, etc., may be used herein to describe various elements, components, regions and/or sections, these elements, components, regions, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, or section from another. Thus, unless expressly stated otherwise, a first element, component, region, or section discussed below could be termed a second element, component, region, or section without departing from the teachings of the present invention.

[0034] As used herein, the term "source" can be used to indicate a single light emitter or more than one light emitter functioning as a single source. For example, the term may be used to describe a single blue LED, or it may be used to describe a red LED and a green LED in proximity emitting as a single source. Additionally, the term "emitter" may indicate a single LED chip or multiple LED chips arranged in an array, for example. Thus, the terms "source" and "emitter" should not be construed as a limitation indicating either a single-element or a multielement configuration unless clearly stated otherwise. Indeed, in many instances the terms "source" and "emitter" may be used interchangeably.

[0035] The term "color" as used herein with reference to light is meant to describe light having a characteristic average wavelength; it is not meant to limit the light to a single wavelength. Thus, light of a particular color

(e.g., green, red, blue, yellow, etc.) includes a range of wavelengths that are grouped around a particular average wavelength.

[0036] Embodiments of the present invention are described herein with reference to conversion materials, wavelength conversion materials, phosphors, phosphor layers and related terms. The use of these terms should not be construed as limiting. It is understood that the use of the term phosphor, or phosphor layers is meant to encompass and be equally applicable to all wavelength conversion materials.

[0037] Embodiments of the invention are described herein with reference to cross-sectional view illustrations that are schematic illustrations. As such, the actual thickness of elements can be different, and variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances are expected. Thus, the elements illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region of a device and are not intended to limit the scope of the invention .

[0038] FIG. 1 shows a perspective view of a light fixture 10 according to an embodiment of the present invention. The fixture 10 can be used in many different applications, but the embodiment shown comprises a troffer-style light fixture sized to fit in, mount to, or suspend from ceilings. For example, the housing may be sized to mount in a conventional ceiling "T-grid". The fixture 10 comprises a housing 12, with the housing 12 having a shape and size similar to those used for conventional fluorescent-type troffer lighting fixtures. The housing provides the general mechanical structure for the fixture 10. The housing 12 can also comprise a plurality of reflective interior surfaces such as those of the pan 14.

[0039] The pan 14 provides a protective perimeter around the light modules 16 that are arranged in an array within the housing 12. In this particular embodiment, the fixture 10 comprises a two-by-two (2 x 2) array. Many other arrays are possible, for example, a two-by-one (2 x 1) or a four-by-one (4 x 1) array. Thus, the modular aspect of the fixture allows for customization to accommodate many different fixture size requirements.

[0040] Each light module 16 comprises reflective panels 18 that define a reflection chamber 20. At least one light emitter 22, often a plurality, is mounted at the base of the reflection chamber 20 such that they initially emit light toward the open end. The emitter can comprise a single LED chip, for example, or it may comprise an array of LED chips. Thus, the embodiment shown is a direct fixture. In other embodiments, the light emitters may be positioned to initially emit light in a direction that is not toward the fixture opening. Such a configuration would be an example of an indirect fixture. The reflective panels 18 redirect light from the emitters 22 toward the open end of the chamber 20 where it interacts with the primary optic 24 as discussed in more detail herein. After passing through the primary optic 24, high-angle light will be redirected off the surfaces of the pan 14 toward the fixture opening and low-angle light will travel directly for the opening. In this embodiment, a secondary optic 26 spans the fixture opening. Substantially all of the light emitted from the fixture 10 interacts with the secondary optic 26, which similarly as the primary optic 24, functions to disperse and the mix the light to provide pleasing luminous output. [0041] It is understood that many different light emitters can be used that are arranged in many different ways, and in some embodiments the different modules can have different types of light emitters. In some embodiments, each of the light emitters can emit light with the same characteristics, such as emission intensity, color temperature, and color rendering index. This can result in the particular fixture emitting a substantially uniform emission across its opening. The light emitters can be LEDs that can generate different colors of light, with the many industrial, commercial, and residential applications calling for fixtures emitting white lights.

[0042] In some embodiments, a multicolor source is used to produce the desired light emission, such as white light, and several colored light combinations can be used to yield white light. For example, as discussed in U.S. Patent Nos. 7,213,940 and 7,768,192, both of which are assigned to Cree, Inc., and both of which are incorporated herein by reference, it is known in the art to combine light from a blue LED with wavelength- converted yellow light to yield white light with correlated color temperature (CCT) in the range between 5000K to 7000K (often designated as "cool white") . Both blue and yellow light can be generated with a blue emitter by surrounding the emitter with phosphors that are optically responsive to the blue light. When excited, the phosphors emit yellow light which then combines with the blue light to make white. In this scheme, because the blue light is emitted in a narrow spectral range it is called saturated light. The yellow light is emitted in a much broader spectral range and, thus, is called unsaturated light. [0043] Another example of generating white light with a multicolor source comprises combining the light from green and red LEDs . RGB schemes may also be used to generate various colors of light. In some applications, an amber emitter is added for an RGBA combination. The previous combinations are exemplary; it is understood that many different color combinations may be used in embodiments of the present invention. Several of these possible color combinations are discussed in detail in U.S. Pat. No. 7,213,940 to van de Ven et al .

[0044] Other light sources can comprise a series of clusters having two blue-shifted-yellow LEDs ("BSY") and a single red LED ("R") . BSY refers to a color created when blue LED light is wavelength-converted by a yellow phosphor. The resulting output is a yellow-green color that lies off the black body curve. BSY and red light, when properly mixed, combine to yield light having a "warm white" appearance. These and other color combinations are described in detail in the previously incorporated patents to van de Ven (USPN 7,213,940 and 7, 768, 192) . The light sources according to the present invention can use a series of clusters having two BSY LEDs and two red LEDs that can yield a warm white output when sufficiently mixed.

[0045] The light sources can be arranged to emit relatively even emission with different luminous flux, with some embodiments having light sources that combine to emit at least 100 lumens, while other embodiments can emit at least 200 lumens. In still other embodiments the lighting sources can be arranged to emit at least 500 lumens . [0046] In one embodiment, the light emitters 22 may be arranged in a single integral "plug-and-play" LED array, such as the CXA line of LED arrays that are commercially available from Cree, Inc. CXA LED arrays are discussed in more detail herein. Many different styles of light emitter arrays may be used.

[0047] The surfaces of the reflection chamber 20 and the pan 14 can be reflective and can be arranged to reflect light from light emitters 22 to illuminate the space below the fixture 10. In some embodiments, the surfaces can comprise a diffuse or reflective coating/layer to help reflect and disperse light from the emitters 22. In some embodiments, the surfaces can comprise a white diffusive material such as a microcellular polyethylene terephthalate (MCPET) material or a commercially available DuPont/WhiteOptics material, for example. Other white diffuse reflective materials can also be used. In other embodiments, the coating/layer can be textured or can comprise a specular or semi-specular coating, layer or surface.

[0048] Diffuse reflective coatings and layers function to mix light from solid state light sources having different spectra (i.e., different colors) . These coatings are particularly well-suited for multi-source designs where two different spectra are mixed to produce a desired output color point. A diffuse reflective coating can reduce or eliminate the need for additional spatial color-mixing; although, embodiments according to the present invention comprise lenses or diffusers used in combination with diffuse reflective coating. In some embodiments, the surfaces can also be coated with a phosphor material that can convert the wavelength of at least some of the light from the light emitting diodes to achieve a light output of the desired color point.

[ 0049 ] In other embodiments the layer 20 can comprise materials other than diffuse reflectors. For example, in some embodiments the coating/layer 20 can comprise a specular reflective material or a material that is partially diffuse reflective and partially specular reflective. In some embodiments, it may be desirable to use a specular material in one area and a diffuse material in another area. These are only some of the many combinations that are possible.

[ 0050 ] The reflective panels 18 and the pan 14 can have many different shapes and sizes and can comprise planar or curved reflective surfaces. The housing 12 can be made of many different materials, with one suitable material for at least some of these being heat conductive, such as a metal, to help in conducting and dissipating heat away from the light sources.

[ 0051 ] In the fixture 10, the primary optic 24 is included in the form of a diffuser. The primary optic is a plate that can cover the individual open ends of each lighting module 16, or, as in this embodiment, the primary optic 24 can be a single translucent plate that spans all of the light modules 16 together. The primary optic 24 of fixture 10 also comprises a polarizing film to polarize the outgoing light which in some cases can reduce glare, although there are many different reasons to polarize the light as it is transmitted.

[ 0052 ] In other embodiments, the primary optic (s) may be moved closer to the emitters in the reflection chamber. For example, in such an embodiment primary optics may be formed to cover each emitter/array individually. The diffusive primary optics can be included over a respective one of the light sources, with some diffuser embodiments comprising scattering particles in a binder. Each diffuser can be arranged to mix light emitted from its light source and to reduce or eliminate the visibility of the discrete LEDs in the light source. Each diffuser can be mounted in place using conventional adhesives or mounting devices, such as snaps or brackets. In some embodiments each diffuser can comprise elements to scatter light from its light source with some embodiments having scattering particles mixed in a material such as glass or plastic. Different scattering particles can be used with some embodiments having scattering particles made alumina, silica, titania, titanium dioxide, or combinations thereof. Different diffusers can have different sizes of scattering particles with some embodiments having particle sizes ranging from 0.1 to 1.0 microns. The diffuser can take many different shapes.

[0053] In some embodiments, the primary optic can comprise a rigid material that is transmissive to the light from the light sources, and can comprise an additional layer or film of scattering material on the rigid material. The thicknesses of the films can be uniform across the diffuser or can have different thicknesses, and can utilize different binder and particle materials. The layer or film can comprise many different material arranged in many different ways, and can be applied using conventional methods such as spraying. In some embodiments a binding material can be used with the scattering layer/film with can be an organic polymer, such as ethyl cellulose, nitrocellulose or poly ( ethylene oxide) or an inorganic polymeric system, such as, silicone or ethyl polysilicate . In still other embodiments the binder can comprise an enamel.

[0054] Different embodiments of diffusers according to the present invention can comprise varying scattering properties along any surface, and for those having a scattering layer along any direction of the interior and exterior surfaces of the diffuser. The diffuser can comprise a transparent material (substrate) comprising a scattering film on an inside surface having varying scattering properties. The scattering films can have many different thicknesses depending at least partially on the film/binder material used, type of scattering material, and the density of scattering material in the film. In some embodiments, diffusers can have a scattering film thickness ranging from 0.1 to 1000 microns, with the film being on the interior and/or exterior.

[0055] Embodiments of the light fixture 10 can also comprise a secondary optic 26 that works in conjunction with the primary optic 24 to disperse and or mix light from the light emitters 22. The secondary optic 26 can be arranged in many different ways. In the embodiment shown the secondary optic spans the opening of the housing 12 so that it covers each of the modules 16. In this embodiment, the secondary optic comprises an acrylic prismatic lens. The secondary optic 26 can be made of the materials described above for the primary optic 24, and can comprise scattering particles as described above. The secondary optic 26 can have a portion of the surface textured or the entire surface textured.

[0056] The primary and secondary optics 24, 26 mix light from light emitters 22 to reduce hot spots and reduce the visibility of different LED emission colors. This allows for a fixture with fewer high output light sources, with the fixture providing an even emission that is visually appealing to occupants of the room being illuminated. In some embodiments, light from each light emitter/array 22 can pass through primary optic 24 and further mix and reflect before then passing through the secondary optic 26. This mixing and reflection can occur in many different ways with some embodiments arranged so that at least some light passing through the primary optic 24 reflects off of the panels 18 of the reflection chamber 20, and then passes through secondary optic 26.

[0057] FIG. 2 is a perspective view of the back side of the fixture 10. The housing 12 comprises several mount features 28 that allow the fixture 10 to be mounted to a "T-grid", for example, such that a portion of the fixture is recessed in the ceiling. The fixture 10 may also be surface mounted to a ceiling or a wall or suspended with a pendant configuration.

[0058] FIGs. 3a-d show four plan views of the fixture 10. FIG. 3a is a bottom view (room side); FIG. 3b is front view; FIG. 3c is a side view; and FIG. 3d is a top view

(ceiling side) . In this particular embodiment the housing 12 is shaped to provide a fixture having a square footprint, although many different footprints are available. Here, the fixture has the exemplary dimensions of 600 mm square, or slightly less than 2 ft x 2 ft. FIG. 3b shows that portions of the housing 12 that form the sides flare out to give the fixture 10 a trapezoidal cross-section when viewed from the front. A flange 30 protrudes out from the edge of the housing 12. The flange 30 may be used to aid with recessed mounting. FIG. 3c shows that the housing 12 has a rectangular cross-section when viewed from the side. A metal bezel 32 frames the perimeter of the fixture opening. This particular fixture has a depth of 120 mm. The FIG. 3d shows the top side of the fixture 10, a portion of which may protrude into the ceiling for mounting. It is understood that the dimensions are merely exemplary and that fixtures of all different sizes are possible.

[0059] FIGs. 4a-c show several views of the fixture 10. FIG. 4a is a front view; FIG. 4b is a side plan view along section line A-A.; and FIG. 4c is a detailed view of the area C. FIG. 4b shows some of the internal components of the fixture 10. The light emitters 22 are disposed at the base of the reflection chamber 20. In FIG. 4c, the detail area C shows the emitters 22 secured to the housing with an emitter holder 34. A heat spreader 36 is interposed between the emitters 22 and the housing 12 to facilitate thermal dissipation away from the emitters, improving emitter lifetime and efficiency. The heat spreader may be made of many thermally conductive materials, with aluminum (Al) being one suitable material. Also, visible in FIG. 4b is a driver circuit 38 which can be seen between two of the light modules 16 in the center region of the housing 12. The driver circuit 38 is discussed in more detail herein.

[0060] FIG. 5a is a back view of the fixture 10. FIG. 5b is a side plan view along section line B-B. In this view, a cross-section of the driver circuit 38 is shown in the center region of the housing 12 in front of two of the light modules 16. Although in this embodiment, the driver circuit 38 is disposed in the center region of the housing 12 and external to the reflection chambers 20, it is understood that the driver circuit can be arranged in many different spaces within the housing. Ideally, the driver circuit 38 is shielded from the light from the emitters 22. FIG. 5c is a perspective plan view along section line C-C. In FIG. 5c, the driver circuit 38 is shown tucked between two adjacent light modules 16 (i.e., in the middle of all four modules 16 if all were visible in this view) . Thus, the driver circuit 38 is not in any significant optical paths where light would impinge on the light-absorptive elements of the circuit 38 and reduce the total output efficiency of the fixture 10.

[0061] The driver circuit 38 is connected to control the light emitters 22 in each of the modules 16. In the embodiment shown, a DC signal from an AC/DC converter can be distributed to the various light sources. The DC signal can be distributed in many different ways, such as through a wiring harness or through printed circuit boards (PCBs) . The wiring harness or PCBs can run along different internal portions of the housing external to the light modules and can have a connector arrangement for connecting to the electrical power to the light emitters 22 at the base of the reflection chambers 20.

[0062] Each light emitter 22 can have its own DC/DC converter that can be on-board or adjacent to the emitter/array that converts signal from the DC output to the appropriate DC level to drive the emitters 22. Each of the DC/DC converters can have additional circuitry to provide other functions, such as compensating and dimming circuitry. These are only a couple of the many functions that can be provided along with the DC/DC converter.

[0063] Having respective DC/DC converters at each emitter array can provide certain advantages. In conventional troffers having the AC/DC and DC/DC converters in one power supply can require factory calibration of the power supply to match it to the light engine of the particular troffer. Thus, if this type of combined power supply malfunctions or fails it can result in complex repair procedures or replacement of the entire troffer or light engine. By having the DC/DC converter at each light source, the AC/DC converter does not need to be set at the factory. A failed or malfunctioning AC/DC converter can be easily replaced in the field. If an on-board DC/DC converter malfunctions or fails at the light source, the light source can be removed and replaced with a functioning source. The DC/DC converter on the light source will have been set to the desired level for that particular light source, so the repair procedure does not require resetting in the field.

[0064] Furthermore, the components for a combined AC/DC and DC/DC converters that drive the entire fixture can also be large and expensive. By making the DC/DC converter on-board and remote at each light source 18, smaller and less expensive components can be used because of the reduced power needed from each converter. A DC/DC converter for the entire fixture would need to accommodate 40 watts of power, or more. By dividing that load into multiple portions, the individual light source need only see 5 watts. This allows for many of the DC/DC circuit components to be consolidated into purpose-built integrated circuits, reducing cost and size. The remote DC/DC converters can also be arranged closer to the LEDs on each light source which can provide for greater driving efficiency and control.

[0065] More details of circuits similar to the circuit 38 are given in U.S. Application Serial No. 13/662,618 titled "DRIVING CIRCUITS FOR SOLID-STATE LIGHTING APPARTUS WITH HIGH VOLTAGE LED COMPONENTS AND RELATED METHODS," which is commonly owned with the present application by CREE, INC., which was filed on 29 October 2012, and which is incorporated by reference as if fully set forth herein.

[0066] Additional details regarding driver circuits are given in U.S. Application Serial No. 13/462,388 titled "DRIVER CIRCUITS FOR DIMMABLE SOLID STATE LIGHTING APPARATUS," which is commonly owned with the present application by CREE, INC., which was filed on 2 May 2012, and which is incorporated by reference as if fully set forth herein.

[0067] Additional details regarding driver circuits are given in U.S. Application Serial No. 13/207,204 titled "BIAS VOLTAGE GENERATION USING A LOAD IN SERIES WITH A SWITCH, " which is commonly owned with the present application by CREE, INC., which was filed on 10 Aug 2011, and which is incorporated by reference as if fully set forth herein.

[0068] FIG. 6 is a block diagram of various circuit components that might be used in a driver circuit according to embodiments of the present invention. Both conventional and renewable power sources 40 may be used to power the fixture 10. The driver circuit 38 may receive information from sensor systems 42 that affects how the light emitters 22 are controlled. Sensors 42 may be housed within the fixture 10 or they may be remote to the fixture. Other control circuits 44, such as dimmer and timing components, may be used to control the output of the emitters 22. In some embodiments, the emitters 22 may be controlled remotely with over a network 46. In other embodiments, the emitters 22 may be controlled remotely over a wireless network 48. Many different component combinations are possible to support a driver circuit that effectively controls the emitters 22.

[0069] FIG. 7 is a perspective view of the bottom of the fixture 10 with the primary and secondary optics 24, 26 removed to reveal the emitters 22. This particular embodiment comprises CXA LED arrays from Cree, Inc. as the emitters 22. The arrays 22 are held by the holder 34 in good thermal communication with the heat spreader 36. FIG. 8 shows a close-up perspective view of one of the light modules 16 that may be used in the fixture 10.

[0070] FIG. 9 is a perspective view of the fixture 10 that is powered up and emitting light. In this embodiment the light emitting from the secondary optic 26 is uniform across the four areas that correspond with the positions of the light modules 16 beneath. The CXA LED arrays 22 are do not exhibit significant imaging under these operating conditions. The fixture 10 provides a uniform, pleasing optical output into the room.

[0071] Fixtures similar to the fixture 10 can be operated with an input power of 120 VAC for U.S. models with available lumen outputs of 2000 lm or 40001m and having a general color rendering index of R_a > 75 for color temperatures of 3000 K or 4000 K. The fixture can operate with a power factor of greater than 0.9 and an International Protection (IP) rating of IP20.

[0072] FIGs. 10-13 are examples of light fixtures according to alternative embodiments of the present invention. These embodiments use the same light module 16 from the fixture 10 as the basic building block for several different lighting applications. [0073] FIG. 10 is a perspective view of a fixture 50 according to an embodiment of the present invention. In this embodiment, the light modules 16 are arranged in a linear four-by-one (4 x 1) array. The housing 52 is designed to provide a surface mounted fixture 50. The fixture 50 may be mounted to a ceiling or a wall with screws, hooks, adhesive, or the like.

[0074] FIG. 11 is perspective view of a fixture 60. This embodiment provides a four-by-four (4 x 4) module array with a housing 62 designed for surface mount applications. In this embodiment, the pan is omitted and the modules themselves are adjacent to the housing 62 to minimize the total fixture footprint in a room space.

[0075] FIG. 12 is a perspective view of a fixture 70 according to an embodiment of the present invention. The light modules 16 are arranged in a two-by-two array. The pan 72 comprises four uniform panels that may be used to provide additional luminous surfaces. For example, the pan 72 may be coated with a white diffuse reflective coating to increase the percentage of the area within the fixture 70 that is visibly luminous from the room. This effect is desirable in some commercial and residential spaces .

[0076] FIG. 13 is a perspective view of a square LED downlight 80. One or more light modules 16 may be used within the can housing 82 to provide the downlight source. The spring clips 84 may be used to clamp the downlight 80 in place when it is recessed into a plenum. A junction box 86 may be mounted directly to the back of the downlight housing 82 as shown.

[0077] FIGs. 14a-h show various views of a linear light fixture 90 according to an embodiment of the present invention: FIG. 14a is top view (ceiling side); FIGs. 14b and 14e are identical end views; FIG. 14c is a side view; FIG. 14d is a bottom view (room side); FIG. 14f is a side plan view along section line A-A; FIG. 14g is a top side perspective view; and FIG. 14h is a bottom side perspective view. The fixture 90 shares several elements in common with the fixture 10 and is structurally similar in many respects. Thus, common reference numerals have been used for like elements. The fixture 90 comprises an elongated housing 92 that surrounds the light modules 16. The modules 16 are arranged in a six-by-one (6 x 1) linear array. For this particular embodiment, the fixture 90 is 1200 mm long, 300 mm wide, and 120 mm deep. However, many other sizes are possible. Mechanically, the fixture 90 functions similarly as the fixture 10. The light is mixed and dispersed by the combination of the primary optics 24 (best shown in light module 16 in FIG. 5c) and secondary optic 94 which in this case is an elongated textured diffuser lens. FIG. 4f shows multiple driver circuits 38 that are arranged along the length of the fixture interior. It may be beneficial to distribute come of the driver circuits 38 as the number of light modules 16 in the fixture becomes larger.

[0078] FIG. 15 is a perspective view of an extended linear fixture 100 that was formed by combining two discreet linear fixtures 100a, 100b. In this way, the fixture 100 can be extended indefinitely in either direction to light a continuous corridor, for example.

[0079] It is understood that embodiments presented herein are meant to be exemplary. Embodiments of the present invention can comprise any combination of compatible features shown in the various figures, and these embodiments should not be limited to those combinations expressly illustrated and discussed. For example, many different driver circuits, optics, and LED components may be used without departing from the scope of the invention. Although the present invention has been described in detail with reference to certain configurations thereof, other versions are possible. Therefore, the spirit and scope of the invention should not be limited to the versions described above.

Claims

WE CLAIM :

1. A light fixture, comprising:

a fixture housing having a fixture opening;

an array of light modules in said housing, each of said light modules comprising:

a plurality of reflective panels defining a reflection chamber having a base and an open end; a plurality of light emitters at said base of said reflection chamber; and

a primary optic proximate to said plurality of light emitters; and

a secondary optic spanning said fixture opening.

2. The light fixture of claim 1, further comprising a reflective pan structure around a perimeter of said light module array and extending between said light module array and said secondary optic.

3. The light fixture of claim 1, wherein said primary optic comprises a diffuser.

4. The light fixture of claim 1, wherein said primary optic comprises a polarized film.

5. The light fixture of claim 1, said plurality of light emitters comprising a light emitting diode (LED) array .

6. The light fixture of claim 1, said secondary optic comprising a prismatic lens.

7. The light fixture of claim 1, further comprising a driver circuit connected to control said plurality of light emitters.

8. The light fixture of claim 1, further comprising a sensor connected to at least partially control said plurality of emitters.

9. The light fixture of claim 1, wherein said array of light modules is in a two-by-two (2 x 2) arrangement such that said light fixture has a square footprint.

10. The light fixture of claim 1, wherein said array of light modules is in a linear four-by-one (4 x 1) arrangement such that said light fixture has a rectangular footprint.

11. The light fixture of claim 1, further comprising a heat spreader at said base of each of said reflector chambers between said light emitters and said housing.

12. A light fixture, comprising:

a fixture housing comprising a reflective pan structure that defines a fixture opening;

a reflection chamber defined by at least one reflective panel;

at least one light emitter in said reflection chamber; and

a primary optic proximate to said at least one emitter; and

a secondary optic spanning said fixture opening.

13. The light fixture of claim 12, said pan structure around a perimeter of said light module array and extending between said light module array and said secondary optic.

14. The light fixture of claim 12, wherein said primary optic comprises a diffuser.

15. The light fixture of claim 12, wherein said primary optic comprises a polarized film.

16. The light fixture of claim 12, said at least one light emitter comprising a light emitting diode (LED) array .

17. The light fixture of claim 12, said secondary optic comprising a prismatic lens.

18. The light fixture of claim 12, further comprising a driver circuit connected to control said plurality of light emitters.

19. The light fixture of claim 12, further comprising a sensor connected to at least partially control said plurality of emitters.

20. The light fixture of claim 12, further comprising a heat spreader in each of said reflector chambers between said light emitters and said housing.

21. A light fixture, comprising:

a fixture housing having a fixture opening;

an array of light modules in said housing, each of said light modules comprising: a reflection chamber defined by at least one reflective panel;

at least one light emitter in said reflection chamber; and

a primary optic proximate to said at least one emitter; and

a driver circuit external to said reflection chambers and between said reflective panels and said housing .

22. The light fixture of claim 21, further comprising a secondary optic spanning fixture opening.

23. The light fixture of claim 22, said secondary optic comprising a textured lens.

24. The light fixture of claim 21, further comprising a reflective pan structure around a perimeter of said light module array.

25. The light fixture of claim 21, wherein said primary optic comprises a diffuser.

26. The light fixture of claim 21, wherein said primary optic comprises a polarized film.

27. The light fixture of claim 21, said at least one light emitter comprising a light emitting diode (LED) array .

28. The light fixture of claim 21, said driver circuit connected to control said plurality of light emitters.

29. The light fixture of claim 21, further comprising a sensor connected to at least partially control said plurality of emitters.

30. The light fixture of claim 21, further comprising a heat spreader at said base of each of said reflector chambers between said at least one light emitter and said housing .