Patent Application
20160377261
Field of the Invention
The invention relates to lighting luminaires and, more particularly, to indirect, direct, and direct/indirect lighting troffers that are well-suited for use with solid state lighting sources, such as light emitting diodes (LEDs).
Description of the Related Art
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. Often the troffer may be recessed into the ceiling, with the back side of the troffer protruding into the plenum area above the ceiling. Typically, 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. Another example of a troffer-style fixture is U.S. patent application Ser. No. 12/961,385 to Pickard, which is commonly assigned with the present application and incorporated by reference herein.
More recently, with the advent of efficient solid state lighting sources, these troffers have been used with LEDs, for example. 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.
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.
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 reproduction. 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 lights 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 savings.
Other 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.
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. Of particular interest is the generation of white light for use in everyday lighting applications. Conventional LEDs cannot generate white light from their active layers; it must be produced from a combination of other colors. For example, blue emitting LEDs have been used to generate white light by surrounding the blue LED with a yellow phosphor, polymer or dye, with a typical phosphor being cerium-doped yttrium aluminum garnet (Ce:YAG). The surrounding phosphor material “downconverts” some of the blue light, changing it to yellow light. Some of the blue light passes through the phosphor without being changed, while a substantial portion of the light is downconverted to yellow. The LED emits both blue and yellow light, which combine to yield white light.
In another known approach, light from a violet or ultraviolet emitting LED has been converted to white light by surrounding the LED with multicolor phosphors or dyes. Indeed, many other color combinations have been used to generate white light.
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. For example, a source featuring blue and yellow sources may appear to have a blue tint when viewed head on and a yellow tint when viewed from the side. 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.
Another known method to improve color mixing is to reflect or bounce the light off of several surfaces before it is emitted from the lamp. This has the effect of disassociating the emitted light from its initial emission angle. Uniformity typically improves with an increasing number of bounces, but each bounce has an associated optical loss. Some applications use intermediate diffusion mechanisms (e.g., formed diffusers and textured lenses) to mix the various colors of light. Many of these devices are lossy and, thus, improve the color uniformity at the expense of the optical efficiency of the device.
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.
Some recent designs have incorporated 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. Examples of indirect fixtures can be found in U.S. Pat. No. 7,722,220 to Van de Ven and U.S. patent application Ser. No. 12/873,303 to Edmond et al., both of which are commonly assigned with the present application and incorporated by reference herein.
Modern lighting applications often demand high power LEDs for increased brightness. High power LEDs can draw large currents, generating significant amounts of heat that must be managed. Many systems utilize heat sinks which must be in good thermal contact with the heat-generating light sources. Troffer-style fixtures generally dissipate heat from the back side of the fixture that extends into the plenum. This can present challenges as plenum space decreases in modern structures. Furthermore, the temperature in the plenum area is often several degrees warmer than the room environment below the ceiling, making it more difficult for the heat to escape into the plenum ambient.
In some cases, it may be desirable to replace or retrofit existing troffer-style fixtures, which have fluorescent light bulbs with newer LED emitters. As such, it can be helpful to design retrofit systems for these fixtures.
The present disclosure describes embodiments of light fixtures. For example, one embodiment of a direct emission light fixture according to the present disclosure comprises a plurality of light sources and a lens over said plurality of light sources. The fixture also comprises first and second end reflectors, wherein one of the end reflectors is movable along the lens. The fixture also includes at least one movable back reflector between said first and second end reflectors.
Another embodiment of a light fixture comprises first and second end reflectors, wherein one of the end reflectors is configured to define an interior compartment. The fixture also comprises at least one back reflector between the end reflectors and a plurality of light sources oriented to output light in the same direction as the fixture. Additionally, the fixture includes a lens over the light sources, wherein one of the end reflectors is movable along the lens.
Yet another embodiment of a light fixture according to the present disclosure comprises a first and second component. The first component comprises first and second end reflectors and a first back reflector between the end reflectors. The first component also comprises a plurality of light sources, such that the light sources are oriented to output light in the same direction as the fixture and a lens over the light sources, wherein at least one of said end reflectors is movable along the lens. The second component comprises a second back reflector and the second component is removably attached to the first component.
A better understanding of the features and advantages of the present embodiments will be obtained by reference to the following detailed description of the invention and accompanying drawings, which set forth illustrative embodiments in which the principles of the invention are utilized.
Embodiments of the present invention provide a direct troffer-style fixture that is particularly well-suited for use with solid state light sources, such as LEDs and retrofit structures for use in pan-style fixtures. The fixture comprises a retrofit troffer assembly that is removably attached within a T grid or pan structure. The pan structure may be an already existing component or may be provided with the retrofit troffer. The retrofit troffer includes a lens structure, which creates an interior space. The interior space created by the lens structure houses light emitters and in some circumstances a light engine and/or additional electronics. First and second end reflectors surround the lens and are disposed at either end of the lens. One or both of these end reflectors may be movable. Optionally, one or more end caps may be incorporated into the end portions of the lens structure to section off the interior space of the lens for housing electronics, such as a light engine. A light board may be removably attached to the base of the lens structure. A back reflector covers most of the interior surfaces of the troffer fixture to direct more light out of the fixture.
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.
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.
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. Thus, the term “source” should not be construed as a limitation indicating either a single-element or a multi-element configuration unless clearly stated otherwise.
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.
Embodiments of the invention are described herein with reference to cross-sectional view illustrations that are schematic illustrations. As such, the actual size 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 any elements of a device and are not intended to limit the scope of the invention.
The fixture described in the present disclosure is a means to easily install a retrofit troffer, as well as to adjust the size and shape of the fixture during installation. The fixture can be adjusted in length by means of sliding at least one of the end reflectors along the length of the lens. The width of the fixture can be adjusted by sliding at least one of the reflectors together or away from one another. This allows the installer the means to make adjustments to the size and shape of the retrofit fixture to accommodate the existing pan and fitting the fixture into the existing pan during installation. The sliding and/or rotating reflectors also make it easier when installing and wiring the fixture. Previously, fixtures would be installed as many different components; however, embodiments according to the present disclosure allow for installation as one or two pieces; end reflectors, back reflector, light engine, and lens. In some embodiments, the fixtures may only be adjusted in size during installation, and returned to a fixed length and width once installation is completed. In other embodiments, the adjustments may be made to the final installed fixture as well.
In some embodiments, the back reflector may be multiple pieces and one of them may be installed separately. Thereby the installer only needs to make one trip up the ladder for the installation. When a person installs an existing retrofit troffer they first have to remove the current fluorescent tubes, lens and ballast cover. Next, they start to install the parts for the retrofit fixture. For the current or previous products available, there are at least 4-6 separate components required for the installation. The installer must go up and down the ladder to collect each component or a second person is required to assist with handing up parts. The fixtures according to the present disclosure are self-contained retrofit troffers that come in one to two pieces. The fixture has interlocking end reflectors, such that one end cap is interlocked with the lens and slides and/or rotates along the lens during installation, while the other end cap may be fixed in place. The back reflectors are also designed to slide away, be removed, or nest during installation and wiring and then be deployed by sliding them down along the end caps and lens, or placing a removed back reflector back in place.
With reference to
The back and end reflectors may comprise many different materials. For many indoor lighting applications, it is desirable to present a uniform, soft light source without unpleasant glare, color striping, or hot spots. Thus, the back reflectors may comprise a diffuse white reflector, such as a microcellular polyethylene terephthalate (MCPET) material or a DuPont/WhiteOptics material, for example. Other white diffuse reflective materials can also be used. The back reflectors may also be aluminum with a diffuse white coating.
It is understood that many different fixture and reflector assemblies may be used to achieve a particular output light profile. The fixtures shown can be provided in many sizes, including standard troffer fixture sizes, such as 2 feet by 4 feet (2′×4′) or 2 feet by 2 feet (2′×2′), for example. However, it is understood that the elements of the shown fixtures may have different dimensions that correspond to the fixture sizes. Furthermore, it is understood that embodiments of the fixture can be customized to fit most any desired fixture dimension.
Various driver circuits may be used to power the light sources. Suitable circuits are compact enough to fit within the compartments, while still providing the power delivery and control capabilities necessary to drive high-voltage LEDs, for example. At the most basic level a driver circuit may comprise an AC to DC converter, a DC to DC converter, or both. In one embodiment, the driver circuit comprises an AC to DC converter and a DC to DC converter, both of which are located inside the compartment. In another embodiment, the AC to DC conversion is done remotely (i.e., outside the fixture), and the DC to DC conversion is done at the control circuit inside the compartment. In yet another embodiment, only AC to DC conversion is done at the control circuit within the compartment.
The light board may be permanently attached or, more likely, may be removably attached to the lens by being slid into a holding mechanism or mounted via alignment holes (not shown). The light board aligns with the center portion of the end reflectors and lens. Additionally, the back reflectors may also be slid into place or mounted via alignment holes. The reflectors and the light boards can be mounted with similar mechanisms, such as retention clips. It is understood that nearly any length of light board can be used. In some embodiments, any length can be built by combining light boards together to yield the desired length. The light sources or emitters can be mounted in a linear pattern or in clusters. In some embodiments, the light sources may be mounted to a light strip and then to the light board.
The lens 102 may be a singular piece or may be constructed of multiple assembled pieces. The lens 102 may be made of plastic, such as extruded plastic. In other embodiments, the front portion of the lens 102 may be made of plastic, such that is it clear or diffuse while allowing light to exit the fixture. In some embodiments, the back area of the lens 102 or the surfaces on the side of the lens adjacent to the light emitters and light board 108 may be reflective. For example, this area may be coated with a white reflective material. In other embodiments, this area of the lens may be sheet metal, such that the front section is extruded plastic, which is snapped in place to a metal back portion. The front area of the lens 102 may be uniform or may have different features and diffusion levels. In other embodiments, portions of the lens may be diffusive, whereas other portions may be reflective. In yet other embodiments, a portion of the lens may be more diffuse than the remainder of the lens.
The troffer fixture may be mounted within a T grid by being placed on the T grid or sandwiched between an existing pan and a T grid. In other embodiments, additional attachments, such as tethers, may be included to stabilize the fixture in case of earthquakes or other disturbances. A tether may be installed after the fixture is put in place and before the second portion of the back reflector is put in place.
The lighting schemes shown in the figures are meant to be exemplary. Thus, it is understood that many different dimensions of light emitter, lens, and reflector combinations can be used to generate a desired output and light color.
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 expressly illustrated and discussed. Many other versions of the configurations disclosed herein are possible. Thus, the spirit and scope of the invention should not be limited to the versions described above.
