This invention relates to light fixtures and, more particularly, to light fixtures using light-emitting diodes (LEDs).
In recent years, the use of light-emitting diodes (LEDs) in development of light fixtures for various common lighting purposes has increased, and this trend has accelerated as advances have been made in the field. Indeed, lighting applications which previously had typically been served by fixtures using what are known as high-intensity discharge (HID) lamps are now being served by LED light fixtures. Such lighting applications include, among a good many others, roadway lighting, factory lighting, parking lot lighting, and commercial building lighting.
High-luminance light fixtures using LED modules as light source present particularly challenging problems. One particularly challenging problem for high-luminance LED light fixtures relates to heat dissipation. Among the advances in the field are the inventions of U.S. Pat. Nos. 7,686,469 and 8,070,306.
Improvement in dissipating heat to the atmosphere is one significant objective in the field of LED light fixtures. It is of importance for various reasons, one of which relates to extending the useful life of the lighting products. Achieving improvements without expensive additional structure and apparatus is much desired. This is because a major consideration in the development of high-luminance LED light fixtures for various high-volume applications, such as roadway lighting, is controlling product cost even while delivering improved light-fixture performance.
In summary, finding ways to significantly improve the dissipation of heat to the atmosphere from LED light fixtures would be much desired, particularly in a fixture that is easy and inexpensive to manufacture.
The present invention relates to improved LED light fixtures. In certain embodiments, the inventive LED light fixture includes a housing and an LED assembly secured with respect thereto. The LED assembly includes an LED illuminator secured with respect to an LED-supporting region of a heat sink with heat-dissipating surfaces extending therefrom. The heat sink has front, rear and lateral sides and is open to ambient-fluid flow to and from the heat-dissipating surfaces along each of the sides. The heat sink defines openings open to ambient-fluid flow to and from the heat-dissipating surfaces. Such openings are along at least two of the sides of the heat sink which are transverse to one another. In some embodiments, the openings are along the two lateral sides and the rear side. The housing and the heat sink may be formed as one piece.
In certain embodiments, the heat sink includes central and peripheral portions. The central portion includes the LED-supporting region and has central heat-dissipating surfaces opposite the LED illuminator. The peripheral portion has peripheral heat-dissipating surfaces along the lateral sides of the heat sink
In some of such embodiments, the openings include at least one central-portion venting aperture facilitating ambient-fluid flow to and from the central heat-dissipating surfaces. The central-portion venting aperture may be adjacent to and partially defined by the housing.
In some embodiments, the central portion includes a plurality of elongate fins protruding from a heat-sink surface which is opposite the LED illuminator. The elongate fins protrude in a direction opposite the LED illuminator and in their lengths extend from distal fin-ends adjacent to the front side of the heat sink to proximal fin-ends adjacent to the rear side of the heat sink. At least one of the proximal fin-ends may be secured to the housing.
In certain of such embodiments, the fins define horizontal between-fin channels open at the distal fin-ends. The proximal fin-ends are configured to permit ambient-fluid flow from the between-fin channels to the at least one central-portion aperture, thereby to facilitate liquid drainage therefrom. The central portion has between-fin surfaces (i.e., the channel bottoms) which may be inclined off-horizontal in the mounted position, thereby to further facilitate liquid drainage from the heat sink.
In certain embodiments, when the fixture is in its mounted orientation, the surface which is opposite the LED illuminator, in particular the surface including the channel bottoms, slopes toward at least two of the sides (e.g., four sides) of the heat sink, thereby to facilitate liquid drainage from the heat sink. In some embodiments, the surface slopes toward at least three of the sides of the heat sink; and in some the surface slopes toward each of the sides of the heat sink.
In some embodiments, the LED assembly is on a bottom surface of the heat sink. The heat sink, when the fixture is in its mounted orientation, includes a top surface which in plan view has a surrounding edge. In some embodiments, the top surface slops downwardly toward the surrounding edge in at least two of the forward, rearward and opposite lateral plan-view directions, thereby to facilitate liquid drainage from the heat sink.
In some embodiments, the top surface slopes toward the at least three of the forward, rearward and opposite lateral plan-view directions. In some of such embodiments, the top surface slopes toward the at least three of the forward, rearward and opposite lateral plan-view directions. In some embodiments, the top surface slopes toward each of such plan-view directions.
In certain of such embodiments, through-openings are formed in the fixture for ambient fluid flow to and from the heat sink. In some of such embodiments, the heat sink defines the through-openings.
In some embodiments, the fixture includes at least one central-portion venting aperture facilitating ambient-fluid flow to and from the top surface. In the embodiments including a housing with the LED assembly secured with respect thereto, the central-portion venting aperture may be at least partially defined by the housing.
In the embodiments where the central portion of the heat sink has a plurality of elongate fins protruding from the top surface in a direction opposite the LED illuminator, the sloping top surface includes between-fin surfaces.
In some of such embodiments, the frame and the heat sink are formed as one piece.
In certain embodiments, the housing includes a housing top surface sloping downwardly in at least two of the forward, rearward and opposite lateral plan-view directions, thereby to facilitate liquid drainage therefrom. The top housing surface may be of a housing upper shell. In some embodiments, the housing upper shell and heat sink are formed as a single piece, whereby the housing upper shell facilitates heat dissipation.
In certain embodiments, the top housing surface slopes toward the top surface of the heat sink, whereby liquid drainage from the housing facilitates cooling of the heat sink.
In some embodiments, the heat sink, the frame and the housing upper shell are formed as a single piece.
The peripheral portion of the heat sink, mentioned above, may also have at least one peripheral-portion opening therethrough along the two lateral sides of the heat sink. These peripheral-portion openings facilitate ambient-fluid flow to and from the peripheral heat-dissipating surfaces. In some of such embodiments, the peripheral portion has at least one peripheral fin along each lateral side of the heat sink. The peripheral fins extends from distal fin-ends adjacent to the front side of the heat sink to proximal fin-ends adjacent to the rear side of the heat sink. In some embodiments, the proximal fin-ends of the peripheral fins is secured to the housing.
The at least one peripheral-portion opening may include at least a pair or as many as several openings between the respective peripheral fin and the central portion of the heat sink. In some embodiments, the peripheral-portion openings are elongate in spaced substantially end-to-end relationship with heat-sink structure extending (laterally from the central portion of the heat sink to the respective peripheral fin) between each adjacent pair of such openings. In some embodiments, the combined length of the openings along each of the respective peripheral fins constitutes a majority of the length of such fin.
In some embodiments, the peripheral heat-dissipating surfaces comprise a plurality of fins extending laterally from the central portion of the heat sink with open spaces between such fins. The central portion may also have a plurality of fins extending forwardly from the central portion of the heat sink with open spaces between the fins.
In some of such embodiments, the heat sink may be an extrusion which has been extruded in a direction orthogonal to both the forward and lateral directions, the extruded dimension of the heat sink being substantially less than the forward-rearward and side-to-side dimensions of the heat sink. In some versions of the extruded heat sink, the central portion of the extrusion includes walls defining a central opening (a void) in the extrusion; and in certain of such versions, in addition to the extrusion, the heat sink includes a mounting plate in thermal contact with the extrusion. In such versions, the LED illuminator is secured to the mounting plate portion of the heat sink.
The LED illuminator may include an LED emitter on a circuit board and an LED optical member over the emitter. The LED emitter may have an array of LED light sources spaced along the circuit board. The LED optical member may have a plurality of lenses each over a corresponding one of the LED light sources. Each LED light source may include an array of LEDs.
In accordance with certain aspects of the present invention, alternative embodiments of the LED lighting system can comprise one or more of the following aspects. In some embodiments, the frame comprises a central portion (which may also be referred to as a core or spine) which has an integral heat sink, at least a portion of the housing that comprises at least one compartment for wiring and/or driver circuitry separate from the LED illuminator, and a mount. The frame further comprises a peripheral portion spaced from the central portion to provide a desired form factor, e.g., such as a cobrahead or other form factor, and/or additional heat sinking In some embodiments, the core has a plurality of compartments, where in some embodiments, at least one of the compartments provides isolation from the LED illuminator. In some embodiments, the heat sink is integrated with a compartment, for example, a heat sink surface can form a compartment wall. In some embodiments, the heat sink can form an integral backlight shield. In other embodiments, the heat sink can comprise a reflective backlight shield. In some embodiments, the core is formed from a single piece of die-cast metal. In some embodiments, the core comprises the top portion of the housing, and a compartment door of metal or a polymeric material provides access, such as 180 degree access, to the compartment(s) in the housing. In some embodiments the heat sink can comprise an extruded part with lateral fins.
In some embodiment, the central portion is integrated with the heatsink, supports the housing and provides mounting to a support member. A top and/or bottom enclosure(s), which can be in the form of a clamshell, engages the core to house electronic components of LED power circuitry.
In some embodiments, the top and/or bottom enclosure can form the peripheral portion of the frame and provide a desired form factor. The top and/or bottom enclosures can be made of metal and/or a polymeric material. In certain embodiments, by using a polymeric material, such as a plastic, nylon or polycarbonate, for the enclosure(s) or doors, the fixture may be able to integrate a fully-enclosed antenna for wireless control of the fixture and be able to provide electrical isolation that allows the use of a removable LED driver. One example of such removable driver is a caseless driver board which is fully encapsulated in a protective polymeric material providing electrostatic discharge (ESD) protection to the driver board which conducting heat away from the driver board during operation.
In some embodiments, the heat sink includes fins in the space between the heat sink and peripheral portions of the frame. In some embodiments, at least one thermal connection is provided between the heatsink and the peripheral portion of the frame in a space between the heat sink and the peripheral portion of the frame. In some embodiments, open through-spaces are provided on multiple axes, e.g., at least one on a side and at least one on the front or back.
In some embodiments, the core can be made at least in part of a polymeric material. In some embodiments, a polymeric mounting arrangement can be used to mount the lighting fixture to a pole. In some embodiments, the entire core is made of a polymeric material.
In some embodiments, a mounting arrangement is provided with an outside fulcrum which allows for a smaller aperture off the back and better clearance for the pole. In some embodiments, the fixture includes a fulcrum outside a fixture interior which provides advantages such as allowing a smaller aperture for a support-member entry into the fixture interior as well as easier access to the interior by providing more room for clearance of a compartment door has more clearance.
The smaller entry aperture may eliminate the need for a splash guard which is typically required for UL listed outdoor light fixtures, while still providing for the possibility of a splash-guard arrangements.
In some embodiment, the enclosure(s), door and/or housing can be molded and can comprise an integral backlight shield or reflector.
The term “ambient fluid” as used herein means air and/or water around and coming into contact with the light fixture.
The term “projected,” as used with respect to various portion and areas of the fixture, refers to such portions and areas of the fixture in plan views.
As used herein in referring to portions of the devices of this invention, the terms “upward,” “upwardly,” “upper,” “downward,” “downwardly,” “lower,” “upper,” “top,” “bottom” and other like terms assume that the light fixture is in its usual position of use.
In descriptions of this invention, including in the claims below, the terms “comprising,” “including” and “having” (each in their various forms) and the term “with” are each to be understood as being open-ended, rather than limiting, terms.
The figures illustrate exemplary embodiments of LED light fixtures in accordance with this invention. Common or similar parts in different embodiments are given the same numbers in the drawings; the light fixtures themselves are often referred to by the numeral 10 followed by different letters with respect to alternative embodiments.
LED assembly 40 includes a heat sink 42 and an LED illuminator 41 secured with respect to heat sink 42. Heat sink 42 includes an LED-supporting region 43 with heat-dissipating surfaces 44 extending from LED-supporting region 43. LED illuminator 41 is secured with respect to LED-supporting region 43. As shown in
In fixtures utilizing a plurality of emitters, a plurality of LEDs or LED arrays may be disposed directly on a common submount in spaced relationship between the LEDs or LED arrays each of which is overmolded with a respective primary lens. These types of LED emitters are sometimes referred to as chip-on-board LEDs. LED optical member 29 is a secondary lens placed over the primary lens. In embodiments with a plurality of LED emitters (packages), optical member 29 includes a plurality of lenses 28 each positioned over a respective one of the primary lenses. The plurality of secondary lenses 28 are shown molded as a single piece 29 with a single flange surrounding each of the plurality of lenses 28.
LED light fixture 10 has a housing 17 and LED assembly 40 is secured with respect to housing 17. Housing 17 has an enclosure 13 which is within rearward region 32 and defines a chamber 14 enclosing electronic LED power circuitry 15. As shown in
With lower shell 35 being of polymeric material, a wireless signal can be received by the antenna which is fully enclosed within chamber 14 along with circuitry for wireless control of the fixture. Such circuitry with the antenna may be included as part of LED driver 150. The advantage of the fully enclosed antenna is also available on other embodiments of this invention having enclosures all or portions of which are non-metallic material.
Housing 17 includes a main portion 171 which includes upper shell 34 and lower shell 35 and also includes a forward portion 172 extending forwardly from main portion 171. (Forward portion 172 of housing 17 is the forward portion of frame 30.) In main portion 171, upper shell 34 forms a housing body 176 and lower shell 35 serves as a cover member 350 movably secured with respect to housing body 176.
As shown in
The nature of the hinging securement is seen in
As shown in
As seen in
Light fixture 10B of the third embodiment, shown in
A fourth embodiment of this invention is illustrated in
The embodiments of
The “short” extrusions of the heat sinks of the fourth and fifth embodiments are facilitated by structure shown best in
The laterally- and forwardly-extending fins are open to free flow of ambient fluid (air and water), and their position and orientation serve to promote rapid heat exchange with the atmosphere and therefore rapid cooling of the LED illuminator during operation. Upwardly-flowing air and downwardly-flowing water (in the presence of precipitation) facilitate effective cooling, and reduce the need for upwardly-extending fins on top of the heat sinks.
Certain aspects are illustrated best by reference to the first embodiment, particularly as shown in
In the second embodiment illustrated in
Referring again to the first embodiment,
Housing upper shell 34 and heat sink 42 are formed as a single piece, whereby the housing upper shell facilitates heat dissipation. The heat sink, the frame and the housing upper shell are formed as a single piece.
In addition to the above-described sloping, LED light fixture 10 has various advantageous structural taperings. As seen best in
As shown in
The various embodiments disclosed herein each illustrate one aspect of the present invention particularly related to the frame and open character of the fixtures. This is discussed in particular with respect to the first embodiment, and in particular with reference to
More specifically, the first embodiment includes the following projected areas:
When describing the openness aspect of this invention using reference to the illuminator plane P indicated in
Using such parameters, the total through-space area in the illuminator plane is slightly over 15% of the fixture area. And, if the light fixture is configured such that the enclosure with its LED power circuitry, rather than being beside the LED assembly, is offset above or otherwise away from the LED assembly (such as being in the support member), then the total through-space area in the illuminator plane may be at least about 40% of the fixture area. Described differently, the total through-space area in illuminator plane P is about two-thirds of the projected LED-assembly area.
While openness is discussed above with particular reference to the first embodiment, it should be noted that
Such openness in an LED light fixture offers great flexibility from the standpoint of form-factor design, e.g., allowing overall shape of the fixtures to better accommodate replacement of existing non-LED fixtures of various shapes. Several of the embodiments disclosed herein have frames which at least in their forward portions provide a footprint substantially similar to the footprint of so-called “cobrahead” light fixtures. This is achieved despite the fact that the LED assemblies used in fixtures according to the resent invention have substantially straight opposite lateral sides, as seen in the figures.
The advantages of the openness disclosed herein extend beyond form-factor concerns. Just one example includes avoiding or minimizing accumulation of snow, leaves or other materials on the fixtures.
Another aspect of the present inventive light fixtures is illustrated in
As seen in
In some prior LED devices, back-light shielding has been in the form of individual shields disposed on a non-preferential side of each LED emitter. Some of such prior shielding was positioned over the exterior of a corresponding lens. In such prior cases, over time the back-light shielding often became covered with dist or other ambient particles and simply absorbed rearward light from the respective LED emitter. Such absorption translated in decreased efficiency of light output from such LED device. In other examples, prior back-light shielding was positioned inside each lens corresponding to each individual LED emitter. While protected from contamination, such shielding resulted in lenses which were both complex and expensive to manufacture. In either type of the back-light shielding disposed on the non-preferential side of each individual LED emitter, there was still some undesired light in the rearward direction. Such light, escaping the prior lens-shield configuration through unintended refraction or reflection by the lens.
In some other prior examples of back-light shielding used in light fixtures, such shields were in the form of a separate structure secured with the spect to the fixture rearwardly to the illuminator. Such separate shielding structures often requires complicated securement arrangements as well as interfered with the overall shape of the light fixture.
The integrated back-light shielding of the present invention, provides effective blocking of rearward light and providing reflection of such light away from areas of undesired illumination. The reflection provides by the integrated back-light shield of this invention facilitates higher light-output efficiency of the LED illuminator used in the LED light fixture of the present invention. The intergated nature of the back-light shielding of the present invention provides all the benefits of a single back-light shield without disruption of the overall shape of the fixture. Furthermore, the back-light shielding of the present invention is defined by surfaces which are open to air and water flow, which facilitates self cleaning of the reflective surface and minimized absorption of light received by such shield surface.
Another aspect of this invention is illustrated best in
Fulcrum 90 is part of a fulcrum member 93 which also includes support structure 95 for fulcrum 90.
The exterior fulcrum provides advantages such as allowing a smaller aperture for a support-member entry into the fixture interior 13 as well as easier access to the interior by providing more room for clearance of a compartment door has more clearance. The smaller entry aperture may eliminate the need for a splash guard which is typically required for UL listed outdoor light fixtures, while still providing for the possibility of a splash-guard arrangements.
As shown in
As further seen in
The outward portion has an outer perimeter which in plan view may be substantially similar to the footprint of a cobrahead non-LED light fixture.
This invention gives great flexibility in providing LED light fixtures for a variety of particular roadway lighting and other similar outdoor lighting purposes.
The desired light-output level determined by the particular application and/or determined by dimensional constrains (e.g., pole height, area to be illuminated, and desired foot-candles of illumination in the target area) can be varied substantially by selection of the particular appropriate LED illuminator and chosen power level, with or without modification of heat-sink size, without departing from a particular desired form factor, such as the above-mentioned “cobrahead” form. The open “footprint” of the fixture of this invention allows such flexibility in a light fixture with advantageous performance characteristics, both in light output and in heat dissipation.
One example of such light fixture is the fixture referred to as the first embodiment. Such particular fixture with a chosen four LED emitters and a heat sink as shown at power level of twenty-four watt gives an output of about 2411-2574 lumens depending on LED correlated color temperature (CCT). The same fixture with applied power of 42 watt gives an output of about 3631-3884 lumens again depending on LED CCT. Higher lumen outputs can be achieved by corresponding adjustments in the number and nature of LED emitters with or without corresponding adjustment of the heat sink. These changes can be made with or without change in the “footprint” of the fixture.
While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting.
This application is a continuation-in-part of U.S. patent application Ser. No. 13/294,459, filed Nov. 11, 2011, which is a continuation of U.S. patent application Ser. No. 12/629,986, filed Dec. 3, 2009, now U.S. Pat. No. 8,070,306, issued Dec. 6, 2011, which is a continuation of U.S. patent application Ser. No. 11/860,887, filed Sep. 25, 2007, now U.S. Pat. No. 7,686,469, issued Mar. 30, 2010, which is a continuation-in-part of now abandoned U.S. patent application Ser. No. 11/541,908, filed Sep. 30, 2006. This application also claims the benefit of U.S. Provisional Application Ser. No. 61/624,211, filed Apr. 13, 2012. The entirety of the contents of each of U.S. application Ser. Nos. 13/294,459, 12/629,986, 11/860,887, 11/541,908 and 61/624,211 are incorporated herein by reference.
Number | Date | Country | |
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61624211 | Apr 2012 | US |
Number | Date | Country | |
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Parent | 12629986 | Dec 2009 | US |
Child | 13294459 | US | |
Parent | 11860887 | Sep 2007 | US |
Child | 12629986 | US |
Number | Date | Country | |
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Parent | 13294459 | Nov 2011 | US |
Child | 13764743 | US | |
Parent | 11541908 | Sep 2006 | US |
Child | 11860887 | US | |
Parent | 29444511 | Jan 2013 | US |
Child | 11541908 | US |