Typically, drop down ceilings, such as the one illustrated in FIG. 1, are used in many commercial and residential building projects when the height of the desired ceiling is lower than the structures actual ceiling height. The drop down ceiling is built using a metal grid which is supported by cables to the actual building. The grid is than populated with ceiling tiles, HVAC ducts and lighting. Such grids have been standardized to 2×2 foot and 2×4 foot sizes in order to make it easier for manufactures of ceiling tiles, HVAC ducts and lighting fixtures to offer standard products.
Lighting fixtures in the 2×2 foot and 2×4 foot sizes have for many years been illuminated using linear fluorescent lamps. These fixtures are sometimes referred to as fluorescent troffers. A fluorescent troffer can include components such as a sheet metal enclosure, a fluorescent ballast, fluorescent lamps and optics to shape the light emitted from the lamps into something pleasing for the environment in which it will be used. A person skilled in the art will recognize three typical types of fluorescent troffers: prismatic, parabolic, and volumetric. One example of a prismatic troffer is illustrated in FIG. 2, and can include, for example, lamps recessed inside the fixture with a lens covering the face of the fixture. One example of a parabolic troffer is illustrated in FIG. 3, and can include, for example, lamps recessed behind or inside cells with no lens covering the fixture. One example of a volumetric troffer is illustrated in FIG. 4, and can include, for example, lamps inside of specially designed reflectors and lenses.
The overall foot print of the various choices of fluorescent troffers, including but not limited to the three main types described herein, are generally the same because they must all drop into 2×2 foot or 2×4 foot grids.
While efforts to make more efficient lighting have led to developments directed to upgrading and replacing fluorescent troffers, such efforts suffer from a number of deficiencies. For example, some efforts that leave existing troffers in place do not improve the overall appearance of the light generated as the old troffers often remain old and dirty. In fact, light that used to be pleasing and have a low glare may be adversely affected. Additionally, because older systems are designed to be used with older technology, the optical efficiency (Lumens per Watt) that exists with newer technology can be lost due to compatibility issues. The optical efficiency (Lumens per Watt) of the total system can be lower than replacement components, or even the old components, and thus the total luminance of the lit space can decrease. Still further, complications can often arise in the re-wiring and re-fitting that is often needed to marry the newer systems with the older systems. Existing retrofitting options can be unreliable at least because the newer components may not fit well with the older components, and the cost associated with purchasing and installing the more efficient lighting can be expensive. New, replacement fixtures are also expensive and can suffer from many of the same complications already discussed. Additional complications can stem from new, replacement fixtures because the ceiling in which the new, replacement fixtures are installed may require modifications to handle different loads.
By way of non-limiting example, one way lighting fixtures having fluorescent tubes are modified to included an LED solution is by replacing the tube with an LED tube having the appropriate sized to fit into the existing fluorescent troffer fixture. The LED tube typically exhibits a Lambertian candela light distribution, as illustrated in FIG. 5. When the LED tube is added to the troffer fixture without any optics, the resulting light distribution from the troffer can also be Lambertian. A person skilled in the art will recognize that Lambertian light distribution is not generally desirable for office-type lighting. Rather, bat wing light distribution, as illustrated in FIG. 6, is more preferable for office environments. Prior to the present disclosure, attempts to achieve bat wing light distribution involved associating secondary optics components with the troffers in which the LED tubes were installed to assist in creating the desired light distribution. Examples of such secondary optics components include a prismatic lens, baffles, or parabolic cells. These attempts, however, particularly in a retrofit setting with LED tubes, were not able to achieve a desirable light distribution. The amount of light for a particular space was often insufficient and included an undesirable amount of glare.
The present disclosure contemplates new and improved devices, kits, and methods for either retrofitting existing overhead lighting systems, or providing new overhead lighting systems that are easier and cheaper to install, perform more efficiently, and minimize and/or overcome many of the aforementioned deficiencies. The present disclosure also contemplates new and improved devices, systems, and methods for improving the distribution of light emanating from a light fixture.