Embodiments of the present invention relate to light fixtures using direct light.
Energy efficiency and environmental impact have become areas of great concern for society. Thus, many cities have adopted “Dark Skies” initiatives that aim to reduce light pollution by encouraging reduced amounts of light in the nocturnal environment. These initiatives encourage using less light in general, using controls (such as on-off capabilities and time-of-night sensors), and using reflectors and shields to reduce nocturnal light. Such measures may result in energy savings resulting in economic benefits, better nighttime ambience and quality of life, conservation of nocturnal wildlife and ecosystems, and increased visibility at night by reducing glare. One organization that supports such initiatives is the International Dark Sky Association.
In keeping with these initiatives, commercial entities and concerned individuals continue to look for ways to reduce their energy consumption and the amount of light that is emitted upward into the sky. Many individuals are looking to replace old light fixtures with newer fixtures or at least to modify existing light fixtures to be more efficient. The concern is generally found in light fixtures that are employed in outdoor settings, such as street or post top fixtures, but is equally applicable to indoor light fixtures.
An existing post top fixture 10 is shown in
Some of the light is emitted towards the intended areas, resulting in direct lighting of the intended area. The direct light must pass through the panes 26 that define the carriage 20. When light passes through the panes 26, it can result in a loss of optical efficiency of around 8%. The tilted panes 26 may also refract light upwards into the sky. If the panes 26 are dirty then optical efficiency and upward refraction and reflection are even more problematic. Additionally, the panes 26 if constructed of glass or brittle plastic are subject to vandalism by people breaking the panes 26. The panes 26 thus result in inefficiency and might create dangerous conditions.
Additionally, some of the light in traditional post top fixtures 10 is emitted upwardly, which wastes energy and violates Dark Skies initiatives. Thus, a reflector 18 may be placed around the cavity 14 and on the underside of the hood 16 to redirect some of the upwardly emitted light back downward into the intended area, thus resulting in indirect lighting of the intended area. While the reflector 18 does tend to minimize the amount of emitted light that is directed upward, it does not eliminate it entirely as a portion of the refracted light traveling through the panes 26 will be redirected upwards.
Commercial entities and concerned individuals may desire to replace these existing post top fixtures 10 with new light fixtures that are more efficient and are in keeping with Dark Skies initiatives. But the cost of completely replacing existing post top fixtures 10 might be prohibitive, and results in landfill waste. Thus, it may be desirable to modify existing post top fixtures 10 to be more efficient and Dark Skies friendly.
Therefore, there is a need for an efficient light fixture that maximizes the amount of direct lighting supplied to an intended area.
There is also a need for a light fixture that minimizes the amount of upwardly directed light, thus minimizing energy loss and light pollution.
There is also a need to modify existing light fixtures to be more efficient and Dark Skies friendly, rather than replacing the existing light fixtures with new light fixtures.
Certain embodiments of the present invention provide a light fixture (including but not limited to an outdoor light fixture) that maximizes the amount of direct lighting into an intended area by using light engines with light sources that emit light directly towards the intended area. Also, the light fixture may be structurally configured to avoid obstruction of the emitted light but rather to ensure that the most light possible reaches the intended area. The light fixture may include a carriage with a first (top) end and a second (bottom) end opposite the first end. A hood may be mounted to the first end of the carriage. At least one light engine may be mounted to the hood. The light engine includes a plurality of light sources that emit light downwardly directly onto an intended area. In some embodiments, the light sources are light-emitting diodes. It may be desirable from a heat transfer and thermal efficiency perspective to mount the light engine(s) onto a mounting plate, which is subsequently mounted to the hood such that the light engines are in close proximity to the hood surface thus minimizing the thermal path for heat from the light engines to travel to the hood surface where it will be radiated and conducted off. Regardless, the light sources are preferably positioned on the light engines and the light engines preferably positioned on the hood so that light emitted from the light sources has an unobstructed path to the intended area. It is preferable, but not required, that the second end of the carriage be shaped and sized so that it does not interfere with emission of the light to the intended area. The light fixture thus provides light in a thermally efficient manner, maximizes the amount of direct light, and limits the amount of light pollution.
One embodiment of the light fixture 100 is shown in
One embodiment of a light fixture 100 may include a carriage 130 that has a first (top) end 138 and a second (bottom) end 140. Side arms 132 extend between the first end 138 and the second end 140, and the side arms 132 are connected by edges 124. While panes may be used, in certain embodiments there are no panes between the side arms 132 so that the space between the side arms 132 is open. Such embodiments might be useful to increase the optical efficiency of the light fixture 100 (because panes may result in a loss of optical efficiency of around 8%) and to minimize any upward refraction or reflection caused by the panes. Although the embodiments of the carriage 130 shown in the figures have a square cross-section (thus, four side arms 132), it should be understood that the shape of the carriage 130 is in no way limited to the shape shown in the figures. Rather, a carriage 130 of any shape or configuration may be used.
In certain embodiments the light fixture 100 also includes a hood 120 coupled to the first end 138 of the carriage 130. It may be desirable for the hood 120 to be opened or removed in order to access inside the carriage 130. Thus, in some embodiments, the hood 120 may be hinged to an edge 124 of the carriage 130 to allow the hood 120 to be opened (such as shown in
The carriage 130 also includes a pole-receiving portion 142 proximate the second end 140 for mounting the light fixture 100 to a pole 150. In
The structural elements of the light fixture 100—including the hood 120, carriage 130, and pole-receiving portion 142—may be made with a variety of materials, including metals (such as stainless steel or aluminum), or plastics. One of skill in the art would recognize that the elements of the light fixture 100 may be made with any suitable manufacturing technique. Alternatively, and as described in more detail herein, one of ordinary skill in the art would understand how to modify an existing post top fixture 10 to create the light fixture 100.
In some embodiments, a mounting plate 200 is mounted to the bottom portion 122 of the hood 120. As shown in
The mounting plate 200 may serve as a mount for light engines 210 with associated light sources 212 and as a heat transfer medium by which heat generated by the light sources 212 is dissipated to the hood 120. To most effectively serve this latter purpose, the mounting plate 200 is preferably made of a thermally conductive material, such as a metal. Any number of light engines 210 may be mounted in any arrangement on a mounting plate 200. There may be a plurality of light engines 210, or only a single light engine. In the embodiment shown in
Other embodiments do not use a mounting plate 200; instead, the light engine(s) 210 are mounted directly to the bottom portion 122 of the hood 120. In such embodiments it may be desirable (but certainly not required) to use a light engine 210 that is square-shaped such as in
The light engines 210 serve as a mount for a plurality of light sources 212. Any number of light sources 212 may be provided on the light engines 210 in any arrangement. The embodiment of a light engine 210 shown in
The light source 212 may include, but is not limited to, a light-emitting diode (an “LED”).
In embodiments that do not have panes in the carriage 130, the light engines 210 are exposed to weather and the elements. Thus, it may be desirable to provide a light engine 210 that is weather resistant. This may be accomplished by sealing the light engine 210 with a protective layer 222 as illustrated in
The light sources 212 emit both light and heat energy. The light sources 212 may become very hot, and thus, it may be desirable to conduct heat away from the light sources 212. It is preferable, but not necessary, that the light sources 212 be positioned on the mounting plate 200 close to the outer edge 220 of the mounting plate 200. In this way, heat generated by the light sources 212 is conducted away from the light sources 212 through the mounting plate 200 and to the hood 120 for dissipation from the light fixture. To facilitate such heat transfer to the hood 120, it may be desirable to provide a thermally conductive material between the bottom portion 122 of the hood 120 and the mounting plate 200 (if a mounting plate 200 is used) or the light engines 210.
All necessary power source(s) and wiring (not shown) needed for the light sources 212 may be positioned in a cavity 232 defined within the hood 120.
The configuration of the light fixture 100 both maximizes the light emitted into the intended area, and minimizes the light emitted in an upward direction (that is, towards the hood 120). Light is generally emitted parallel to the optical axis 216 of the light source 212 (shown in
While not required, provision of lip 126 along the bottom portion 122 of the hood 120 prevents light emitted by the light sources 212 from escaping upwardly from the fixture. The depth of the lip 126 and the depth at which mounting plates 200 are recessed within hood 120 may be adjusted to control such upward emission. Thus, light pollution is minimized, as in line with several Dark Sky initiatives. Manufacturing expenses and time are reduced because there is no need to provide reflectors of other structures that result in indirect lighting. The configuration of light fixtures 100 according to this invention produces a higher lumen per watt than traditional light fixtures.
One of skill in the art would understand how to modify an existing post top fixture 10 to create the light fixture 100 described herein. For example, the light source 12 may be removed from the cavity 14. A mounting plate 200 with associated light engine(s) 210 as described herein could be mounted onto the hood 16. Any desired power source or wiring (not shown) could be stored in the cavity 14. If desired, the panes 26 could be removed to increase optical efficiency. Thus, modifying an existing post top fixture 10 may also result in a light fixture 100 as described herein. Manufacturing expenses and waste are reduced by modifying existing post top fixtures 10.
The foregoing is provided for purposes of illustration and disclosure of embodiments of the invention. It will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, it should be understood that the present disclosure has been presented for purposes of example rather than limitation, and does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.
This application claims to the benefit of Application Ser. No. 61/211,725, filed on Apr. 2, 2009 and entitled “Light Fixture,” the entire contents of which are incorporated by reference.
Number | Name | Date | Kind |
---|---|---|---|
6328457 | Huang | Dec 2001 | B1 |
6776508 | Bucher et al. | Aug 2004 | B2 |
6784357 | Wang | Aug 2004 | B1 |
6871985 | Humphrey | Mar 2005 | B2 |
D537556 | Summerford et al. | Feb 2007 | S |
7204618 | Kuelbs et al. | Apr 2007 | B1 |
7241023 | Carpenter | Jul 2007 | B1 |
7278761 | Kuan | Oct 2007 | B2 |
7420811 | Chan | Sep 2008 | B2 |
7488093 | Huang et al. | Feb 2009 | B1 |
7665866 | Mayer et al. | Feb 2010 | B2 |
7682049 | Zheng et al. | Mar 2010 | B2 |
7828461 | Mayer et al. | Nov 2010 | B2 |
7841734 | Wilcox | Nov 2010 | B2 |
7914182 | Mrakovich et al. | Mar 2011 | B2 |
8021027 | Galipeau et al. | Sep 2011 | B2 |
8157413 | Maxik et al. | Apr 2012 | B2 |
20050146874 | Cech et al. | Jul 2005 | A1 |
20060044789 | Curtis | Mar 2006 | A1 |
20060092638 | Harwood | May 2006 | A1 |
20060105485 | Basin et al. | May 2006 | A1 |
20060109647 | Liu | May 2006 | A1 |
20060250803 | Chen | Nov 2006 | A1 |
20060285310 | Shyu | Dec 2006 | A1 |
20060291218 | Pazula | Dec 2006 | A1 |
20070159819 | Bayat et al. | Jul 2007 | A1 |
20070201228 | Young | Aug 2007 | A1 |
20070242451 | Richmond | Oct 2007 | A1 |
20080031013 | Ruggles et al. | Feb 2008 | A1 |
20080062689 | Villard | Mar 2008 | A1 |
20080062691 | Villard et al. | Mar 2008 | A1 |
20080074867 | Chen | Mar 2008 | A1 |
20080089070 | Wang | Apr 2008 | A1 |
20080218992 | Li | Sep 2008 | A1 |
20080232094 | Ramsdell | Sep 2008 | A1 |
20090073681 | Chen | Mar 2009 | A1 |
20090237934 | Zeng et al. | Sep 2009 | A1 |
Number | Date | Country |
---|---|---|
WO-2009145883 | Dec 2009 | WO |
Entry |
---|
Non-Final Office Action issued Feb. 15, 2011 in related Canadian Application No. 2,689,403 entitled “tight Fixture”: 2 pages. |
Number | Date | Country | |
---|---|---|---|
20100254134 A1 | Oct 2010 | US |
Number | Date | Country | |
---|---|---|---|
61211725 | Apr 2009 | US |