Patent Application
20170016608
The present disclosure is directed generally to a luminaire for casting light over a desired area. More particularly the present disclosure is directed to a luminaire having a circuit board against a heat sink and a lens enclosing the circuit board in the luminaire with lens spacers between the lens and the circuit board forcing the circuit board against the heat sink to facilitate thermal contact.
It is known that some light generating sources (hereinafter “light source”) operate more efficiently when their temperature is managed or maintained at certain levels. A light emitting diode (hereinafter “LED”) is known to be an efficient light source relative to many other current commercially available light sources. It is also known, however, that the efficiency of LEDs decreases as the temperature of the LED increases. Furthermore, operating an LED at a higher temperature also tends to decrease the lifespan of that LED. When operating LEDs for light-generating purposes, it can therefore be desirable to regulate the temperature of the LEDs and maintain that temperature at a certain preferred operating temperature or in a certain preferred operating temperature range. Light sources other than LEDs would also benefit from temperature regulation.
A luminaire can be designed to act as a heat sink for an associated light source and to dispel heat to the surrounding environment. When a luminaire comprises one or more light sources that are mounted to, or otherwise part of, a circuit board, thermal management of light sources may be accomplished by creating thermal contact between the circuit board and the luminaire so as to allow the luminaire to act as a heat sink. Thermal contact between a circuit board and its associated luminaire has been facilitated by screwing the circuit board to the luminaire or connecting the circuit board to the luminaire by other connectors. Using screws to create a thermal connection between a circuit board and a luminaire necessitates providing a threaded receptacle in or behind the luminaire to receive each screw. Creation of these threaded receptacles is time consuming and costly. Moreover, securing the circuit board to the luminaire with screws in this matter requires careful advancing of the screws in order to avoid damaging the circuit board or stripping the threads in the threaded receptacle. This too becomes time consuming and costly and can result in damaged circuit boards regardless of how carefully the screws are advanced. Similar problems and costs are associated with other manners of attaching a circuit board to a luminaire in a manner sufficient to create a thermal connection there between.
There is a need for a luminaire overcoming the issues described above and of the type described herein.
A luminaire is disclosed comprising a housing comprising a housing plate and a lens frame; a circuit board defining a front side and a rear side, the circuit board rear side resting on the housing plate; a plurality of light sources extending from the front side of the circuit board; a plurality of circuit board bosses mounted to the front side of the circuit board; a lens held between the lens frame and the circuit board bosses such that the lens presses the circuit board against the housing plate. The housing plate may act as heat sink to draw heat from the circuit board. The housing plate may define a substantially planar surface. The circuit board may rest on the substantially planar surface of the housing plate. At least one of the plurality of light sources may be an LED. The circuit board bosses may extend from the circuit board front side to a distal end in contact with the lens. The circuit board bosses may extend from the circuit board front side to a distal end that extends further from the circuit board front side than any light source. The circuit board bosses may comprise a body and at least one terminal extending from the body and connected to the circuit board. The circuit board bosses may comprise a body and at least one terminal extending from the body and soldered to the circuit board. The circuit board boss may have a body comprised of silicone. The circuit board bosses may have a body and a mounting leg extending from the body to a mounting plate connected to the circuit board.
Another luminaire is disclosed comprising a housing comprising a housing plate; a circuit board defining a front side and a rear side, the circuit board rear side resting on the housing plate; a plurality of circuit board bosses mounted to the front side of the circuit board and extending outward from the circuit board to a circuit board boss distal end; and a lens in contact with the circuit board boss distal ends and biased toward the circuit board such that the lens presses the circuit board against the housing plate. The circuit board may comprise light sources. The housing may comprise a lens frame biasing the lens toward the circuit board.
Another luminaire is disclosed comprising: a housing comprising a housing plate and a lens frame; a circuit board defining a front side and a rear side, the circuit board rear side resting on the housing plate; a plurality of light sources extending from the front side of the circuit board: a lens having a plurality of posts extending therefrom toward a distal end in contact with the circuit board such that the lens presses the circuit board against the housing plate, at least one of the plurality of posts comprising a plurality of fingers at the distal end. The housing plate may act as heat sink to draw heat from the circuit board. The circuit board may define an aperture which defines an aperture perimeter and the plurality of fingers in contact with the aperture perimeter. A distal end of the fingers may define a distal end of the post and defining a wedge, and the circuit board defining an aperture which defines an aperture perimeter and the wedge of at least one finger in contact with the aperture perimeter. At least one of the posts may be formed integrally with the lens. At least one of the posts may be comprised of the same material as the lens. The lens may be concave.
Aspects and embodiments of the present disclosure may be more fully understood from the following description when read together with the accompanying drawings, which are to be regarded as illustrative in nature, and not as limiting. The drawings are not necessarily to scale, emphasis instead being placed on the principles of the disclosure. In the drawings:
The embodiments depicted in the drawing are merely illustrative. Variations of the embodiments shown in the drawings, including embodiments described herein, but not depicted in the drawings, may be envisioned and practiced within the scope of the present disclosure.
Aspects and embodiments of the present disclosure provide luminaires and elements thereof. Luminaires according to the present disclosure can be used for new installations or to replace existing luminaires or elements thereof. Such luminaires and elements afford light distribution and lower costs due to simple and efficient product configuration and corresponding assembly which lower manufacturing and assembly costs. Such luminaires also provide increased thermal management resulting in higher operating efficiencies through reduced energy consumption and maintenance.
A first exemplary embodiment of such a luminaire is luminaire 100 depicted in
A plurality of circuit board bosses 114 are distributed over the circuit board front side 108b and extend farther from the circuit board front side 108b than any light source 112. A protective lens 110 is held between the housing plate 104 and the lens frame 106 such that the lens 110 is pressed against the circuit board bosses 114 forcing the circuit board rear side 108a into firm contact with the housing plate 104 to facilitate excellent thermal conductivity between the circuit board 108 and the housing plate 104. In this configuration, the housing plate may act as a heat sink drawing heat from the circuit board 108, including the light sources 112. Because the circuit board bosses 114, along with force from the lens 110, provide intimate contact between the circuit board rear side 108a and the housing plate, the circuit board 108 need not be connected to the housing with screws or other typical connection hardware. The need for holes in the housing 102 to accept such connection hardware and/or threading of such holes is eliminated by the luminaire 100. Assembly operations to connect the circuit board 108 to the housing 102 with such connection hardware, and the associated risk of damaging the circuit board 108 during such operations, is also eliminated.
In one exemplary embodiment of the disclosed luminaire 100, the housing plate 104 defines a rear side 104a and a front side 104b. The rear side 104a may comprise heat dissipation fins (not depicted) or other features (not depicted) to increase heat transfer from the housing plate 104 to the surrounding environment. The housing plate front side 104b defines a substantially planar surface 104c across a majority of its face to accept and provide intimate contact with circuit board rear side 108a, which is also substantially flat. In alternative embodiments, the face of the housing plate front side need not be substantially planar if the circuit board 108 is not substantially planar since the objective is to have as much thermal contact as possible between the circuit board rear side 108a and the housing plate front side 104b. The substantially planar surface 104c of the housing plate 104 is surrounded by a lens boss 104d that extends about the periphery of the substantially planar surface 104c like a bank.
As depicted in
The circuit board bosses 114 are depicted as approximating a cube shaped body, although other shapes (e.g. cylindrical) are also contemplated, defining a distal end 114a for engaging the lens when the luminaire 100 is assembled and a proximate end 114b located in contact with, or adjacent to, the circuit board 108 when affixed thereto. The proximate end 114b of the body of each circuit board boss 114 defines two recesses 114c on opposing sides. A terminal 114d extends out of each recess 114c.
In one embodiment of the circuit board boss terminals 114d depicted in
The circuit board boss terminal connector plates 160 each have an associated solder pad 108c on the circuit board 108 and to which the connector plates 160 are affixed via soldering, preferably during the circuit board manufacturing process, to affix the circuit board bosses 114 to the circuit board 108. Other manners of affixing the circuit board boss terminals 114d to the circuit board 108 are also contemplated. For example, an adhesive could replace the circuit board boss terminals 114d and the circuit board solder pads 108 such that the circuit board boss 114 is adhered to the circuit board 108.
The body of each circuit board boss 114 may be comprised of silicone or other like material. It has been found that a hardness measuring approximately between 60 A and 70 A on a durometer is sufficient to achieve the purpose described herein. Other hardness values and/or materials will also facilitate the objectives of this disclosure. In the depicted embodiment, the circuit board bosses 114 have draft angled sides and rounded corners to facilitate mold release.
The lens frame 106 is secured to the housing plate 104 with screws or the like such that the lens frame 106 forces the lens 110 against the seal 116, if present, and against the distal end 114a of each circuit board boss 114 on the circuit board 108. This, in turn, forces the proximate end 114b each circuit board boss 114 against the circuit board 108 front side 108b which, in turn forces the circuit board rear side 108a against the housing plate front side 104b to facilitate heat transfer. A thermally conductive grease or the like could also be inserted between the housing plate front side 104b and the circuit board rear side 108a to maximize thermal contact.
In order to assure that the circuit board bosses 114 create the desired forces discussed above, the height of the circuit board bosses 114 need be high enough that the distal end extend beyond the housing plate lens boss 104d and the seal, if any, so that securement of the lens frame 106 and lens 110 to the housing plate 104 compresses the circuit board bosses 114. The relative height of the circuit board bosses 114 to the housing plate lens boss 104d and seal, if any, as well as the hardness of the circuit board bosses 114 should be designed to provide an appropriate amount of force on the circuit board to achieve the desired thermal contact between the circuit board rear side 108a and the housing plate front side 104a without providing so much force as to crack or otherwise damage the circuit board 108. These aspects are determinable by one of ordinary skill in the art after having read this disclosure.
In the depicted embodiment, the circuit board bosses 114 are spread somewhat evenly across the circuit board 108 in order to somewhat evenly distribute the force applied to the circuit board 108. It will be recognized that a balance must be struck between the cost that the circuit board bosses 114, as well as their installation, and using enough circuit board bosses 114 to spread the force out across the circuit board 108 to maximize thermal contact between the circuit board 108 and the housing plate 104. The embodiment of
A second exemplary embodiment of a luminaire of the present invention comprises a housing having a housing plate 104′ and a lens frame for being connected to the housing plate, all as described and depicted with regard to the luminaire 100 of the first embodiment. The second embodiment luminaire also comprises a circuit board 108′ of the same configuration and placement as the circuit board 108 of the first embodiment luminaire 100, defining a rear side 108a′ and a front side 108b′ with the circuit board rear side 108a′ resting on the housing plate 104′ and having a plurality of light sources 112′ formed on, or secured to the circuit board front side 108b′ for generating light. Unlike the first embodiment luminaire 100, the second embodiment luminaire has no circuit board bosses on the circuit board 108′.
Like the first embodiment, the second embodiment also has a protective lens 110′ that is held between the housing plate 104′ and the lens frame. The lens 110′ defines an inner side 110a′ and an outer side 110b′. Unlike the lens 110 of the first embodiment, the lens 110′ of the second embodiment luminaire comprises a plurality of posts 200 extending from the lens inner side 110a′ toward the circuit board 108′. The posts 200 are configured and sized to press the circuit board 108′ against the housing plate front side 104b′ to facilitate contact and thermal conductivity, as discussed in the first embodiment luminaire 100. Like the circuit board bosses 114 of the first embodiment, the posts 200 eliminate any need for the circuit board 108′ to be connected to the housing with screws or other typical connection hardware. The need for holes in the housing plate 104′ or other portions of the housing 102′ to accept such connection hardware and/or threading of such holes is also eliminated. Assembly operations to connect the circuit board 108′ to the housing 102′ with such connection hardware, and the associated risk of damaging the circuit board 108′ or the housing 102′ during such operations is therefore also eliminated.
One embodiment of the lens post 200 of the second embodiment is depicted in
Each post 200 defines a preferably solid base 206 from which extending from the lens 110′. The remainder of the post 200, including and extending beyond the chamfered tip, defines a cross-shaped cutout defining four fingers 208, which are preferably like-shaped, forming a 90′ angle near the post longitudinal axis 210 and rounded at the outer perimeter 212 of the post 200. The term “cutout” is not intended to imply any method of formation of the posts 200 or fingers 208, which may include, as discussed above, molding. The chamfered tip of each finger 208 defines the wedge 214 angled from the post outer perimeter 212 inward to the post distal end 204, which defines the most distal portion of the finger 208 and the lens post 200.
In the luminaire of this embodiment, the circuit board 108′ defines a plurality of apertures 216 defined by a circuit board aperture inner edge 216a in the front side 108b of the circuit board. The aperture may, but need not depending on the thickness of the circuit board, extend as a through-hole through to the circuit board rear side 108a as in the depicted embodiment.
Each aperture 216 is sized slightly larger than necessary to receive the distal end 204 of the associated finger 208. Each aperture 216 is aligned with one of the wedges 214 on the fingers 208 such that each post distal end 204 is located in an associated circuit board aperture 216 with a portion of the wedges 214 in contact with a portion of the circuit board aperture inner edge 216a or the rim it forms at the circuit board front side 108b. The length of each post 200 is configured such that the distal end 204 of each finger 208 will extend into an associated circuit board aperture 216 when the luminaire of the second embodiment is fully assembled. This configuration is depicted in
Depending on the exact length of the post 200, the exact diameter of the circuit board aperture 216, the exact thickness of the circuit board 108′ as well as many other dimensions of the various portions of the luminaire of this second embodiment, the length of the lens post 200 may be longer necessary to achieve the desired thermal contact between the circuit board rear side 108a′ and the housing plate front side 104b′. Such an unduly long lens post 200 can create problems in a luminaire such as cracking the circuit board 108′ (which could lead to defective or no operation of the circuit board 108′), cracking of the lens 110′, incomplete assembly of the lens frame to the housing plate 104′ (potentially creating for a leak around a seal there between) or other problems. In order to prevent an unduly long lens post 200 from creating such problems, each finger 208 will flex inward toward the post longitudinal axis 210′. One exemplary depiction of such a flexed state appears in
As discussed above, the circuit board aperture 216 could be a through aperture extending from the front side 108b′ to the rear side 108a′ or the circuit board aperture 216 could be replaced with a cup-shaped object on the circuit board front side 108b′. Other alternative configurations will be readily apparent.
The number of lens posts 200 and associated circuit board apertures 216 can be determined based on the size and weight of the circuit board, its rigidity and propensity to sag and other relevant features contributing to the force needed to create thermal contact between the circuit board rear side 108a′ and the housing plate front side 104b′. It will be understood that some subset of the posts 200 could be configured as described above while others lack the described fingers 208 and associated flexibility. The posts 200 could be molded as part of the lens 110′ or created separately and affixed to the remainder of the lens 110′ with adhesive or the like.
In either of the above luminaire embodiments, the lens 110, 110′ may optionally be manufactured to have concave curvature directing the centermost portion of the lens 110, 110′ inward toward the light sources 112, 112′, when the lens is in a relaxed state, to compensate for any sag in the lens 110, 110′ occurring due to the weight of the lens 110, 110′ as it extends inward from the lens frame without support or to compensate for sag in the circuit board 108, 108′. The extent of the curvature depends on the area covered by the lens 110, 110′, the thickness and material from which the lens 110, 110′ is constructed, the area covered by the circuit board 108, 108′, its composition and distribution of elements and their associated weight and the thickness and material from which the circuit board 108, 108′ is made. Other factors will also impact the necessary curvature of the lens 110, 110′ to compensate for sag in the lens 110, 110′ and/or the circuit board 108, 108′.
The LEDs used as the light sources 112, 112′ in the exemplary embodiments herein can be of any kind, color (e.g., emitting any color or white light or mixture of colors and white light as the intended lighting arrangement requires) and luminance capacity or intensity, preferably in the visible spectrum. Color selection can be made as the intended lighting arrangement requires. In accordance with the present disclosure, LEDs can comprise any semiconductor configuration and material or combination (alloy) that produces the intended array of color or colors. The LEDs can have a refractive optic built-in with the LED or placed over the LED, or no refractive optic; and can alternatively, or also, have a surrounding reflector, e.g., that re-directs low-angle and mid-angle LED light outwardly. In one suitable embodiment, the LEDs are white LEDs each comprising a gallium nitride (GaN)-based light emitting semiconductor device coupled to a coating containing one or more phosphors. The GaN-based semiconductor device can emit light in the blue and/or ultraviolet range, and excites the phosphor coating to produce longer wavelength light. The combined light output can approximate a white light output. For example, a GaN-based semiconductor device generating blue light can be combined with a yellow phosphor to produce white light. Alternatively, a GaN-based semiconductor device generating ultraviolet light can be combined with red, green, and blue phosphors in a ratio and arrangement that produces white light (or another desired color). In yet another suitable embodiment, colored LEDs are used, such are phosphide-based semiconductor devices emitting red or green light, in which case the LED assembly produces light of the corresponding color. In still yet another suitable embodiment, the LED light board may include red, green, and blue LEDs distributed on the printed circuit board in a selected pattern to produce light of a selected color using a red-green-blue (RGB) color composition arrangement. In this latter exemplary embodiment, the LED light board can be configured to emit a selectable color by selective operation of the red, green, and blue LEDs at selected optical intensities. Clusters of different kinds and colors of LED are also contemplated to obtain the benefits of blending their output.
Although the embodiments described herein use LEDs to generate light rays, other light sources are also contemplated. The disclosed luminaire is not limited to use of LEDs.
While certain embodiments have been described herein, it will be understood by one skilled in the art that the methods, systems, and apparatus of the present disclosure may be embodied in other specific forms without departing from the spirit thereof. For example, while aspects and embodiments herein have been described in the context of certain applications, the present disclosure is not limited to such; for example, embodiments of the present disclosure may be utilized generally for any light distribution applications.
Accordingly, the embodiments described herein, and as claimed in the attached claims, are to be considered in all respects as illustrative of the present disclosure and not restrictive.
