1. Technical Field
The subject matter of the present disclosure relates to the illumination arts, lighting arts, solid-state lighting arts, and related arts.
2. Description of Related Art
In the field of lighting, solid state devices (e.g., light emitting diode (LED) devices) and other highly efficient light emitting devices are becoming more and more popular because they present many advantages including lower energy consumption, longer lifetime, faster switching, and greater durability and reliance. Although many lighting devices still adopt conventional technology, e.g., incandescent lights and bulbs, as their light sources, there are already many lighting devices using solid state devices instead of conventional light sources to avoid disadvantages, e.g., short lifetime, low light emitting efficiency, and sometimes environmentally unfriendly operation.
As one example, solid-state lighting technologies such as LEDs and LED devices often have performance that is superior to incandescent lamps. This performance can be quantified by its useful lifetime (e.g., its lumen maintenance and its reliability over time). For example, whereas the lifetime of incandescent lamps is typically in the range about 1000 to 5000 hours, lighting devices that use LED devices are capable of operation in excess of 25,000 hours, and perhaps as much as 100,000 hours or more.
A challenge with solid-state technology is the need to adequately dissipate heat. LED devices are highly temperature-sensitive in both performance and reliability as compared with incandescent or other conventional technology (e.g., halogen filaments). To address these features, known lighting devices will place a heat sink in contact with or in thermal contact with the LED device. Such passive cooling systems, however, often do not provide adequate dissipation of thermal energy and, in some cases, may block light that the LED device emits. Moreover, use of fans and similar air moving devices to promote active cooling may not fit within the physical constraints such as regulatory limits that define maximum dimensions for the resulting lighting devices.
This disclosure describes, in one embodiment, a lighting device that comprises an air moving device and a heat sink element. The heat sink element comprises a plurality of fin members disposed about a central axis and forming a cavity to receive the air moving device therein. The plurality of fin members form peripheral channels terminating at peripheral openings on the peripheral edge of the heat sink element. In one example, the fin members are arranged in an inlet grouping through which air flows into the lighting device and an outlet grouping through which air flows out of the lighting device and which is angularly offset about the central axis relative to the inlet grouping.
This disclosure also describes, in one embodiment, a lighting device that comprises a heat sink element with a central axis and having fin members forming peripheral channels that terminate at peripheral openings disposed about the central axis and at the peripheral edge of the heat sink element. The lighting device also comprises a light source in position on a first side of the heat sink element and an air moving device in position on a second side of the heat sink element and aligned with the central axis. In one example, the fin members are arranged in an inlet grouping and an outlet grouping that is angularly offset from the inlet grouping about the central axis. During operation of the air moving device, air flows into the lighting device via the peripheral openings in the inlet grouping and out of the lighting device via the peripheral openings in the outlet grouping.
This disclosure further describes, in one embodiment, a lighting device that comprises a light source and a cooling system in thermal contact with the light source. The cooling system comprises peripheral openings disposed at the peripheral edge of the lighting device, the peripheral openings arranged as part of an inlet grouping and an outlet grouping that is angularly offset from the inlet grouping. In one example, the cooling system can generate a flow pattern in which air flows into the lighting device via the peripheral openings in the inlet grouping and out of the lighting device via the peripheral openings in the outlet grouping.
Other features and advantages of the disclosure will become apparent by reference to the following description taken in connection with the accompanying drawings.
Reference is now made briefly to the accompanying drawings, in which:
Like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated.
Broadly, the embodiments of the lighting devices below incorporate an active cooling solution to dissipate heat from the lighting device. These embodiments deploy an air moving device to create a flow pattern in which air enters and exits the lighting device. The resulting flow pattern, however, occurs at the peripheral edge of the lighting device. This flow pattern can improve cooling efficiency and efficacy because the distribution of air at the periphery and/or the peripheral edge prevents re- circulation of heated air back into the lighting device with air drawn into the lighting device. This feature ensures ingress of cooler air into the lighting device to promote convection and, ultimately, to help dissipate more thermal energy from inside of the lighting device out to the surrounding environment.
The lighting device 100 has a central axis CA and includes a housing 102 with a cover element 104 and a connector element 106. A lens element 108 diffuses light, e.g., to form a light beam or other illumination pattern that exits the housing 102. As discussed more below, the lighting device 100 has inlet and outlet features that circumscribe the peripheral edge 110 of the lighting device 100. Examples of the lighting device cause air to flow into and out of the housing 102 at various locations about the peripheral edge 110 to effectively dissipate heat that arises, e.g., from the light source of the lighting device 100. The position of the inlet and outlet features on the peripheral edge 110 improves cooling efficiency and efficacy by, in one example, creating a flow pattern that reduces re-circulation of heated air the lighting device 100 expels during operation.
Examples of inlet and outlet features can cover particular radial sections (examples of which are found in
The inlet sections 122, 124 and the outlet sections 126, 128 may comprise equal portions of the peripheral edge 110. In the examples of
On the second side 136, the heat sink 132 can have a lip or protruding element, which in the illustration of
A light source 146 resides in the second cavity 144. The light source 146 can have one or more light emitting devices 148 as the primary light source. Examples of the light emitting devices 148 can include light emitting diodes (LEDs) as well as other types of light-emitting devices, e.g., incandescent devices that use incandescent filaments, halogen devices that use a halogen capsule, fluorescent devices that use a fluorescent tube, high intensity discharge (HID) devices, and combinations thereof. The light-emitting devices 148 can also encompass organic and inorganic light-emitting diodes (LED) devices of various constructions. These LED devices can comprise bare semiconductor chips, encapsulated semiconductor chips, as well as various configurations of chip packages in which the LED device is mounted on one or more intermediate elements such as a sub-mount, a lead-frame, a surface mount support. In one example, the LED device can incorporate a reflective member in the form of a cup, dome, cylinder, and/or other shape to direct light, e.g., away from the light source 148 toward the lens element 108. In still other examples, the LEDs can comprise a coating or other material layer, e.g., a wavelength-converting phosphor coating with or without an encapsulant.
The heat sink element 132 can be formed monolithically as a single, integrated component (e.g., with the web member 138, the fin members 140, and the protruding element 142 integrated together). Such construction may lend itself to certain manufacturing techniques, e.g., techniques to cast and/or mold the heat sink element 132. In other constructions, the heat sink element 132 may comprise an assortment of separate pieces that are assembled and secured together using one or more known fasteners, e.g., screws, bolts, and adhesives.
As discussed above, in one aspect, construction of the lighting device 100 facilitates transfer of thermal energy from the light source 146 and out of the lighting device 100. For example, the heat sink element 132 can comprise materials and/or components with properties to conduct and dissipate thermal energy and, in particular, thermal energy on the scale the light source 148 can generate. These materials can include metals, plastics, and composites having a thermal conductivity from about 1 W/(m-K) to 2000 W/(m-K). As shown in
During operation, the air moving device 130 generates a flow of air that travels through the channels between the fin members 140 toward the periphery of the lighting device 100. This flow contacts the surface of the fin members 140, thereby generating convective dissipation of thermal energy from the heat sink element 132 into the moving air. The heated air exhausts to the periphery of the lighting device 100 as the outlet flow 118, 120. The web member 138 prevents air from flowing downward, e.g., into the second cavity 144. In one embodiment, the lighting device 100 can include an additional air diverting member in the form of, for example, a cylindrical sleeve 150 that mates with the heat sink element 132, e.g., to the fin members 140. The cylindrical sleeve 150 is useful to direct air towards the peripheral edge 110, where the air is expelled from the lighting device 100.
Construction of the fin members 204, e.g., the shape, contour, and/or other features, can facilitate both dissipation of thermal energy and air flow. In one example, it may be advantageous to construct the fin members 204 to have the largest available surface area for conduction and/or convection of thermal energy. As shown in
Construction of the heat sink element 202 forms, in one example, a peripheral channel 234 between adjacent fin members 204 that circumscribe the peripheral edge of the heat sink element 202. The peripheral channel 234 terminates at a peripheral opening 236 that exposes the peripheral channel 234 to the surrounding environment. Air flows into and out of the heat sink element 202 via the peripheral openings 236, as generally shown by the arrow 238 (also “inlet air 238) and the arrow 240 (also the “outlet air 240”). In one implementation, during operation of the fan unit 214, inlet air 238 flows into the peripheral openings 232 and traverses the peripheral channels 234 in the inlet groupings 206 and 208. The inlet air 238 circulates throughout the heat sink element 202, e.g., throughout the bore 232. Operation of the fan unit 214 directs the inlet air 238 to the peripheral channels 234 in the outlet groupings 210, 212, where the outlet air 240 flows out of the peripheral openings 232.
As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
This written description uses examples to disclose embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Number | Date | Country | Kind |
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201210260962.1 | Jul 2012 | CN | national |