The present invention relates generally to lighting fixtures and luminaires, and more particularly, relates to a lighting fixture having enhanced heat sink performance with a heat sink member that attaches diffusers, internal reflectors and inserts to enhance light distribution for various applications.
Today many companies are offering decorative outdoor light emitting diode (LED retrofit kits and new LED fixtures in order to take advantage of the long life, excellent color and beam control and other benefits of LEDs. LEDs are temperature sensitive and generate a significant amount of heat, which must be removed from the fixture in order to assure long life and adequate illumination.
To date, most manufacturers have placed LEDs on heat sinks or printed circuit boards, which are either inside the optical and/or housing area or are mounted to an opaque metal top to provide heat extraction from the fixture. The problem with these designs is the high thermal resistance from LED heat source to the outside ambient air. Much of the heat remains trapped inside the optical cavity and lowers the life expectancy of the LED and limits the wattage of the LED light engine. Therefore, the life expectancy and total lumen package is less than is required for many applications. To date, no solution has been developed to provide for enhanced thermal performance with the light fixture having an external heat sink while incorporating several features to improve luminous light output or dispersion and directional control in many different application settings.
High power LED arrays are also very bright and it is both unappealing in many applications and, due to glare, poor for visibility where the individual LED array are visible as points of light. The use of LED arrays and a specially designed diffuser and the directional application of the LED arrays through an internal specially shaped reflector and various inserts minimizes glare and enhances aesthetic design and distribution of light.
A need exists for a new lighting fixture that employs features for improved heat dissipation and improved light distribution.
Disclosed is a LED light fixture which has a top side and a bottom side. The top side is basically pointing toward the ceiling when it is mounted on the inside of a building, and the bottom side is pointed toward the floor of the building. When mounted in a parking lot or in an outdoor situation, the light fixture would typically have the top side pointing to the sky and the bottom side pointing toward the ground. The light fixture is made up of a body which includes a heat sink ring with outwardly radiating fins. The heat sink ring would typically be a metal such as aluminum, and would be ring like with outwardly radiating fins. The purpose of the heat sink ring is to absorb heat from the LED arrays, which are mounted adjacent to the heat sink ring, and to radiate the heat through the radiating fins to keep the LED arrays and the electronics from overheating and shortening their life.
The device includes an attachment means, which can be a place where a mounting bracket is screwed into the top side of the light fixture, or it can be a place where an arm such as from a light pole screws into the top or side of the light fixture body with bolts. Other attachment means are possible such as a U bracket, loop or D ring which is hung from hooks or otherwise attached to a ceiling or light pole.
The inside surface of the heat sink ring is comprised of a number of sloped planar facets, forming a polygonal inside surface of the heat sink ring, with each polygon sloped slightly from the vertical to direct the light from the LEDs towards the bottom side of the light fixture. The LEDs would be present in arrays of LEDs which are attached to the inside surface of the heat sink ring. Adjacent to the heat sink ring and the LED light arrays is a reflector dish which is attached to the fixture body. The reflector dish is smaller in diameter than the inside diameter of the heat sink ring, and is placed approximately level with the LED light arrays. The outside surface of the reflector dish is sloping in relation to the LED arrays, so that light from the LEDs strikes the reflector dish and is reflected in a downward direction, toward the bottom side of the light fixture. The light fixture further includes a diffuser lens which is frosted or prismatic or having other surface angles to help diffuse the light coming from the LED light arrays. One version of the diffuser lens can have sloping sides, which slope toward the center of the light fixture, with a flat bottom. The diffuser lens can be made of any translucent or transparent material, and plastic is a practical material for use in the diffuser lens.
One version of the reflector dish is generally shaped like a portion of a sphere, with a rim around the base and the reflector dish curving in a general spherical shape. Another version of the reflector dish is one in which the dish is generally shaped like an inverted pie pan, with a flat bottom. The sides of this reflector dish are generally sloped, and are formed into flat facets, which are positioned to correspond with the facets on which the LED arrays are placed. In this way, each LED array is facing the facet of the pie pan reflector dish, which causes light to be reflected toward the bottom side of the light fixture and away from the top side. In this manner, very little light is directed upward from the light fixture and most of the light is directed in a downward fashion from the light fixture. The light from the LED arrays is columnated, so that it is less diffuse when it strikes a surface which may be a long distance below the light fixture. This results in more light hitting the area under the light fixture, or less power expended on delivering the same lumens onto the surface below the light.
The present invention together with the above and other objects and advantages may best be understood from the following detailed description of the preferred embodiments of the invention illustrated in the drawings, wherein:
In accordance with features of the invention, a lighting fixture having an enhanced light distribution technology is disclosed.
The lighting fixture of the disclosed technology is shown in
The light fixture body 22 of
The heat sink ring 24 is typically one solid piece of aluminum, which has fins 34 radiating out from the periphery in a radial manner. Alternatively, the heat sink ring 24 and the light fixture body 22 can be formed as separate pieces which fit together, and alternatively the radiating fins 34 can also be a separate piece which attaches to the outside of the heat sink ring 24.
Shown in
Shown in
The light fixture body also has an attachment means 26. One means of attachment would be for 26 to include a threaded opening so that a mounting post or electrical conduit can extend into the threads of the light fixture body and lock in place with a nut which goes on the threads of the pipe or conduit. Wiring would come through the conduit and provide electrical energy to the LED arrays.
The LED arrays 32, such as Bridgelux BXRA 50C1100, are driven at 500 ma each with a total of 11 watts, not including the power supply. The fixture efficacy or lumens per watt for the lighting fixture with these LEDs is greater than 80 lumens per watt. The optical efficiency of the lighting fixture is greater than 80%.
The ring shaped heat sink member is suited for dissipating at least 300 watts of heat, in an ambient temperature of 25 degrees C. and resulting in a maximum case temperature of 65 degrees C. on the above LED arrays 32. The device can include wedge shaped inserts which may be placed on the surface of the sloped planar facets 30. LED arrays 32 are placed on the inserts, with the inserts thus changing the direction of light leaving the LED arrays 32. Typical inserts would be wedge shaped devices, approximately as wide as the sloped planar facets, or about 3 inches wide, and 1.5 inches tall.
There may be a plurality of inserts 36 on any or all of the sloped planar facets 30 of the heat sink member. The insert may be made of a thermally conductive material, such as aluminum and is either painted or anodized to protect the insert from corrosion.
The reflector dish is in the direct path of a portion of the light emitted from the LED array 32 and directs more of the light in the downwardly direction than would occur without the reflector dish. The reflector dish is made from a highly reflective aluminum member. The reflector dish is positioned to intercept part of the light from the LED arrays, and redirect it downward. The reflector may be those shown, or could be a ring of angled units, or could be individual units set up in front of each LED array. The LED arrays can be thought of as putting out light in a hemispherical field, with about 60 degrees of light to one side of a center or perpendicular plane, and 60 degrees of light on the other of the center plane. The reflector dish is positioned to intercept, reflect and redirect the light on the upward side of the plane, which is about 25-35% of the light from the LED array, by reflecting and redirecting most of the light from the upward side of the hemispherical field in a downward direction. The light on the other side of the plane continues on to the diffuser lens unimpeded. This is shown in
This application claims the benefit of U.S. Provisional Application No. 61/864,805, filed Aug. 12, 2013, the disclosure of which is incorporated by reference.
Number | Name | Date | Kind |
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20110228550 | Robinson | Sep 2011 | A1 |
20110249441 | Donegan | Oct 2011 | A1 |
20120039073 | Tong | Feb 2012 | A1 |
20120051054 | Kauffman | Mar 2012 | A1 |
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20130322074 | Guercio | Dec 2013 | A1 |
Number | Date | Country | |
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20150043206 A1 | Feb 2015 | US |
Number | Date | Country | |
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61864805 | Aug 2013 | US |