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Invention first embodiment pertains to a downlight luminaire. More specifically, the first embodiment pertains to a downlight luminaire having a first heat dissipation subassembly and a reflector which is in direct thermal communication with a LED printed circuit board assembly so as to dissipate heat through two structures and provide higher efficiency of operation.
Additionally, a second embodiment pertains to a downlight luminaire. More specifically, the second embodiment pertains to a downlight luminaire having a retaining ring positioned within the luminaire reflector for supporting an optical assembly and reflecting light to a center area beneath the downlight in order to provide higher illumination directly beneath the luminaire.
Recessed downlight luminaires are extremely popular due to their unobstructive, hidden nature within a ceiling and the versatility provided by the various types of downlights available. Downlights may be used to provide wall wash, normal downlight or highlight a specific area.
As the popularity of these luminaires has grown, improvements have been continually made to improve the operating efficiency and lighting characteristics. For example, downlights have been developed to operate with compact fluorescent lamps (CFLs). Even more efficient than CFLs, it would be desirable to develop downlights to operate specifically with light emitting diodes (LEDs). However, when LEDs are positioned in deep round reflectors, there is a propensity to have a dark area in the center of a light dispersion graph. As shown in
Another area of desired improvement is with operating efficiency. In general, LEDs have the potential to provide a higher efficiency and longer life than other light sources. LEDs have a higher operating efficiency in part due to cooler operating temperatures. Moreover, LEDs do not burn out like incandescent bulbs, but instead dim over the course of their life. When LEDs operate at cooler temperatures, they operate more efficiently, meaning higher light output for given input energy. Additionally, with more efficient operation at cooler temperatures, the LEDs have longer life. As temperatures increase however, the efficiency decreases and the life is reduced.
Downlights are typically positioned in a plenum or similar volume above a ceiling. Since this plenum area is typically enclosed, the heat from the downlight has a tendency to build up and over a period of time and the temperature is higher than the temperature below, in the illuminated area. Since the illuminated area below the light is cooler than the volume above, it would be desirable, from an operating efficiency perspective, to transfer some heat to this area beneath the luminaire in order improve LED performance and life.
Given the foregoing deficiencies, it would be desirable to overcome the above and other deficiencies.
A heat dissipation assembly for an LED downlight, comprises an LED printed circuit board assembly having a first surface, a second surface and a plurality of LEDs on one of the first surface and the second surface, the LED printed circuit board assembly engaging a primary reflector on a second surface, wherein the LED printed circuit board assembly transfer thermal energy in a first mode to the heat sink and in a second mode to the primary reflector. The heat dissipation assembly further comprising a thermal interface disposed on one side of the LED printed circuit board assembly and engaging a heat sink. The heat dissipation assembly wherein the thermal interface is disposed on between the LED printed circuit board assembly and the heat sink. The heat dissipation assembly wherein the thermal interface compensates for surface irregularities to improve thermal transfer from the LED printed circuit board assembly to the heat sink. The heat dissipation assembly further comprises an air gap disposed between the LED printed circuit board assembly and the primary reflector. The heat dissipation assembly wherein the air gap inhibits transfer of thermal energy from the heat sink to the reflector.
A heat dissipation assembly for an LED downlight, comprises a heat sink, an LED printed circuit board assembly having a plurality of light emitting diodes electrically connected to the LED printed circuit board assembly, a primary reflector disposed beneath the heat sink, the primary reflector having a collar, the LED printed circuit board assembly engaging the collar and dissipating heat in a secondary manner through the primary reflector. The heat dissipation assembly further comprising a thermal interface having a first surface and a second surface, one of the first and second surfaces engaging the heat sink, the other of the first and second surfaces engaging the LED printed circuit board assembly. The heat dissipation assembly further comprising a second thermal interface between a surface of the LED printed circuit board assembly and the primary reflector. The heat dissipation assembly wherein the thermal interface transfers thermal energy and compensates for surface irregularities between the heat sink and the LED printed circuit board assembly. The heat dissipation assembly wherein the LED printed circuit board assembly have a printed circuit board and a plurality of LEDs.
A heat dissipation assembly for an LED downlight comprises a heat sink in thermal communication with an LED printed circuit board assembly, a metallic reflector in thermal communication with the LED printed circuit board assembly, the LED downlight dissipating heat through the LED printed circuit board assembly and through the reflector to increase the efficiency of the LED printed circuit board assembly. The heat dissipation assembly further comprising at least one of the heat sink and the reflector separated from the LED printed circuit board assembly by a thermal interface. The heat dissipation assembly wherein the heat sink and the metallic reflector are not in separated, inhibiting thermal transfer between the heat sink and the metallic reflector. The heat dissipation assembly the primary reflector having an upper collar. The heat dissipation assembly further comprising at least one fastener extending through the upper collar, the LED printed circuit board assembly and into the heat sink. The heat dissipation assembly wherein the at least one fastener sandwiches the LED printed circuit board assembly against a thermal interface for improved thermal transfer. The heat dissipation assembly wherein the metallic reflector is separated from the heat sink.
A better understanding of the embodiments of the invention will be had upon reference to the following description in conjunction with the accompanying drawings in which like numerals refer to like parts throughout the several views and wherein:
It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings.
Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention and that other alternative mechanical configurations are possible.
Referring now in detail to the drawings, wherein like numerals indicate like elements throughout the several views, there are shown in
Referring initially to
The LED downlight 10 utilizes an upper heat sink structure to dissipate heat as part of the heat dissipation subassembly 12. The device further utilizes the primary reflector 14 as a second heat dissipation means in order to further dissipate heat from the device which increases the efficiently and life of the LEDs utilized within the downlight 10. In the exemplary embodiment, the heat sink 20 and the reflector 14 do not touch one another. This creates the two modes of heat dissipation and inhibits transfer of heat from the heat sink 20 through the reflector 14.
Referring now to
The primary reflector 14 is formed of a spun aluminum material and may be finished in various manners including an anodized diffuse or specular finish, a clear finish, a painted finish or another reflective metalized finish, for example. Since the primary reflector 14 is also used as a secondary heat dissipation means, the reflector 14 is preferably also made up a material having a good thermal conductivity characteristics.
Referring to
Referring still to
Referring now to
Exploded from the LED metal core printed circuit board 32 are a plurality of LEDs 34 and a power connector 36. The LEDs 34 are available from a variety of manufactures and are electrically connected to the printed circuit board 32. The LEDs 34 may emit any color desired for any given lighting application and may be selected by a lighting designer for example. Additionally, the LED printed circuit board assembly 30 comprises 16 LEDs 34 although this number is merely exemplary and therefore should not be considered limiting.
Beneath the heat dissipation subassembly 12 and the LED printed circuit board assembly 30 is the primary reflector 14. The retaining ring 60, optical assembly 50 and the mixing chamber 40 are positioned up through the lower opening of the primary reflector 40 against the upper shoulder or collar 15 of the reflector 14. The mixing chamber 40 comprises of a fastener 19 extending from a central location which passes through the opening in the primary reflector 14 and upwardly through the LED printed circuit board assembly 30 and the thermal interface 28 and heat sink 20. The fastener 19 is tightened by the subassembly nut 18 so that the mixing chamber 40 and optical assembly 50 are held in position. According to this embodiment, the upper heat dissipation system are held in place by the four screws and the lower optical system are held in position by the fastener 19.
Beneath the primary reflector 14 is a mixing chamber 40. The mixing chamber 40 collects and redirects the light emitted from the various LEDs 34 while also inhibiting visual recognition of any single LED 34. Because each LED may differ slightly in color, the mixing chamber 40 combines the light into a single output color and does so in an efficient manner. The exemplary mixing chamber 40 is a plastic subassembly, although other materials could be used, comprising a reflective material or coating along an inner surface thereof, described further herein. The mixing chamber 40 is generally frusto-conical in shape with an upper surface 42 and a frusto-conical sidewall 44 extending from the top wall 42 down to a lower flange 46. The top wall 42 includes a plurality of apertures which are aligned with the LEDs 34 therein or at least allow light to pass there through. The mixing chamber 40 further comprises a plurality of keying or positioning spacers 48 extending from the sidewall 44 in order to properly position the mixing chamber within the inner surface of the primary reflector 14.
Exploded from the mixing chamber 40 is a reflective material 38. The reflective material 38 may be a film, tape or coating positioned on an upper inner surface of the mixing chamber 40 beneath the LED printed circuit board assembly 30. The reflective film 38 has a plurality of apertures through which the LEDs or light output from the LEDs may pass into the mixing chamber 40.
Also exploded from the mixing chamber 40 is the reflective inner surface material 41. The reflective material may be a 3M polyester film having a marketing name, “Vikuiti”. The material 41 is positioned along the inner surface of sidewall 44 so as to reflect light from the inner surface of the mixing chamber 40. In an alternative embodiment, the mixing chamber 40 may be formed of metallic material which may be polished so that the reflective film 41 is not utilized. In further embodiments, the mixing chamber 40 may either be painted or have a treated metallic surface so as to reflect light in a desirable manner.
Beneath the mixing chamber 40 is an optical assembly 50. The optical assembly 50 moves the light source from the LEDs 34 to an effective light source at the lens 58. Additionally, the optical assembly 50, in combination with the mixing chamber 40, helps to output a single mixed light rather than multiple distinct sources from the multiple LEDs. The optical assembly 50 may include a lens 58, a diffuser, and/or a phosphor system 54 or any combination thereof. The diffuser 52 spreads and controls the light output from the down light 10. The diffuser 52 may be one of glass or a polycarbonate and may be smoothly finished or may have a plurality of prismatic structure, grooved or other light controlling implements. Similarly, the lens 58 may be formed of glass, polycarbonate or other such material. On the upper surface of the diffuser 52 may be a phosphor system 54, which may be used to control lighting color. Alternatively, the LED's 32 may be white LEDs so as to eliminate the need for the phosphor system 54.
Beneath the optical assembly 50 is a retaining ring 60. The retaining ring 60 is formed of stamped aluminum and may be anodized to a specular finish. Alternatively, other materials and finishes may be utilized. The retaining ring 60 has a cylindrical shape with a retaining lip 62 therein. The retaining lip 62 provides a seat for the optical assembly 50 to be seated in the retaining ring. The retaining ring 62 also serves a secondary function of reflecting light from the lower surface, downward. This directs a higher amount of light downwardly, beneath the downlight 10 and increases the light output in this area of a light distribution graph, as shown in
Referring now to
The lower surface of the retaining ring 62 also serves as a secondary reflector. Ray traces R are indicated reflecting from the inner surface of lip 62 downwardly which result in higher light distribution beneath the downlight 10. This is indicated graphically in
Referring now to
Referring now to
Referring to
The foregoing description of structures and methods has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.
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