The present disclosure relates to light sources and, more particularly, to a lighting module.
A light-emitting device, such as a light-emitting diode (LED), is an attractive candidate for replacing conventional light sources such as incandescent, halogen and fluorescent lights. LEDs have substantially higher light conversion efficiencies than incandescent and halogen lights and longer lifetimes than these types of conventional light sources. Some types of LEDs have higher conversion efficiencies than fluorescent light sources. LEDs require lower voltages than fluorescent lights and contain no mercury or other dangerous materials. Some light-emitting devices have been used to replace high-intensity discharge (HID) lights to provide high levels of light over large areas that require greater energy efficiency or light intensity. Such areas include roadways, parking lots, pathways, large public areas, and other outdoor applications.
In one aspect of the present disclosure, A lighting module includes a light-emitting device configured to emit light, a thermal interface configured to conduct heat away from the light-emitting device, an optical element configured to transmit the emitted light in a light distribution pattern on an area located a distance away from the lighting module, and a reflective surface configured to redirect a portion of the light transmitted by the optical element.
It is understood that other aspects of apparatuses and methods will become readily apparent to those skilled in the art from the following detailed description, wherein various aspects of apparatuses and methods are shown and described by way of illustration. As will be realized, these aspects may be implemented in other and different forms and its several details are capable of modification in various other respects. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.
Various aspects of apparatuses and methods will now be presented in the detailed description by way of example, and not by way of limitation, with reference to the accompanying drawings, wherein:
Various aspects of the disclosure will be described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms by those skilled in the art and should not be construed as limited to any specific structure or function presented herein. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein, one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of this disclosure, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure and/or functionality in addition to or instead of other aspects of this disclosure. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.
Disclosed is an apparatus that may be used for retrofitting a conventional lighting system, such as a street light. In one example, a street light may have a head including a light source comprising one or more light-emitting devices, an optical element, and one or more reflectors configured to reflect light emitted by the one or more light-emitting devices to the optical element to produce a light distribution pattern from the head. The one or more light-emitting devices may produce Lambertia light, such that an observer perceives a constant brightness across the one or more light-emitting devices. The light produced by the light-emitting devices may be used to illuminate a reflector. The reflector may be used to transform the Lambertia light to collimated light and direct the collimated light towards the optical element. The optical element may be configured to produce the light distribution pattern from the collimated light.
By way of example, “street light” may refer to any lighting system that provides any illumination to a street, road, walkway, tunnel, park, outdoor facility, parking lot, or the like. A “pole” may refer to any structure for supporting a lighting system, such as a light post, hi-bay support, wall mounting, suspended hanging fixture, support frame, ceiling mount, or the like. A “thermal management system” may comprise at least a heat sink, heat spreader, heat fin, heat pipe, thermal interface material, active air movement devices, or the like.
An example of a light-emitting device is an LED. An LED is a semiconductor material impregnated, or doped, with impurities. These impurities add “electrons” and “holes” to the semiconductor, which can move in the material relatively freely. Depending on the kind of impurity, a doped region of the semiconductor can have predominantly electrons or holes, referred to as an n-type or p-type semiconductor region, respectively. In LED applications, the semiconductor includes an n-type semiconductor region and a p-type semiconductor region. A reverse electric field is created at the junction between the two regions, which causes the electrons and holes to move away from the junction and towards an active region. When a forward voltage sufficient to overcome the reverse electric field is applied across the p-n junction, electrons and holes are forced into the active region and combine. When electrons combine with holes, they fall to lower energy levels and release energy in the form of light.
The electrodes 106, 108 may be formed on the surface of the epitaxial-layer structure. The p-type semiconductor region 118 is exposed at the top surface and, therefore, the p-type electrode 106 may be readily formed on the p-type semiconductor region 118. However, the n-type semiconductor region 114 is buried beneath the p-type semiconductor region 118 and the active region 116. Accordingly, to form the n-type electrode 108 on the n-type semiconductor region 114, a portion of the active region 116 and the p-type semiconductor region 118 is removed to expose the n-type semiconductor region 114. After this portion of the epitaxial-layer structure is removed, the n-type electrode 108 may be formed.
One or more LEDs may be used to construct a light-emitting device. A light-emitting device having multiple LEDs disposed on a single substrate, as will be described in connection with
The light-emitting device 200 may be configured to produce white light. White light may enable the LED device to act as a direct replacement for conventional light sources used today in incandescent, halogen, fluorescent, HID, and other suitable lights. There are at least two suitable ways of producing white light. One suitable way is to use individual LEDs that emit wavelengths (corresponding to certain colors, such as red, green, blue, or amber) and then mix all the colors to produce white light. Another suitable way is to use a phosphor material to convert monochromatic light emitted from a blue or ultra-violet (UV) LED to broad-spectrum white light. The present disclosure, however, may be practiced with other LED and phosphor combinations to produce different colored lights.
In another example, each LED 301 of a white-light light-emitting device 300 may have its own phosphor layer. Other configurations of LEDs 301 and other light-emitting cells may be used to create a white-light light-emitting device 300. The present disclosure is not limited to light-emitting devices that produce only white light and may be extended to lighting-emitting devices that produce other colors of light.
Street lights may be designed to provide improved visibility and increased safety on a roadway while making efficient use of energy. A street light provides illumination in a particular light distribution pattern. The Illumination Engineering Society (IES) has established a series of lateral distribution patterns, which are designated as Types I, II, III, IV, and V. High-intensity discharge (HID) lights may be used in street lights. LEDs may replace HID lights.
In some embodiments, the light emitted from the light-emitting devices 430 may be Lambertian patterned light. The Lambertian patterned light may be used to illuminate a reflector 450 and/or may be directed to optical element 440. Optical element 440 may be used to transform the Lambertian patterned light and/or internally reflected light to produce a desired light distribution pattern 425.
Optical element 440 may comprise one or more mirrors, lenses and other elements that may be configurable to accommodate various heights 415 of the street light 400, light distribution patterns 425, illumination intensities, and/or size of the light-emitting device 430.
In certain embodiments, systems, apparatus and methods are provided to facilitate rapid and/or easy replacement of a lighting module in a street light or other lighting device. A lighting module may comprise one or more light-emitting devices 430 and an optical component that diffuses, collimates, focuses or otherwise modulates light to obtain a desired light distribution pattern 425.
In some embodiments, the thermal interface 510 may be characterized by low thermal resistance and high electrical resistance. Thermal interface 510 may be multilayered. For example, the thermal interface 510 may include a relatively thin electrical isolation layer that is bonded to a surface of the thermal interface 510. An electrical isolation layer may be created through an oxidation of a surface of the LED array 504 and/or the heat sink 506. In some embodiments, electrical isolation is not desired or required and the heat sink 506 may provide a portion of an electrical circuit that includes the LED array 504. For example, the heat sink 506 may provide a grounding connection for the lighting module 520, 530.
The lighting module 520, 530 may be fitted into a base plate 514 mounted within the head 502. Base plate 514 may be constructed from a metal, polymer, ceramic, a composite or other material having sufficient tensile strength to support the lighting module 520, 530 and a relatively heavy heat sink 506. Base plate 514 may be configured to adapt head 502 for use with the lighting module 520, 530, thereby replacing incandescent, fluorescent or HID lights with an array 504 of light-emitting devices. For example, the base plate 514 may be used to adapt a head 502 that is otherwise configured for use with an HID light. Base plate 514 may be adapted by, for example, providing holes, threads or other elements configured to receive one or more fasteners used to attach base plate to the head 502. In some embodiments, the base plate 514 may comprise an adapted or original base plate 514 that is used to attach HID or another type of light to the head 502. The base plate 514 may attach directly to the heat sink 506, which may attach to the LED arrays 504, thermal interface 510, and/or optical element 512. The heat sink 506 may comprise fins 508 to increase surface area exposed to air in order to permit rapid dissipation of heat generated by the LED array 504. The heat sink 506 may be constructed from a low-thermal resistance material, and the heat sink 506 may have sufficient volume and density to absorb cyclic variations in heat generation.
The optical element 512 typically comprises one or more lenses, mirrors, reflectors and/or prisms that receive light from the LED array 504 and that produce one or more light distribution patterns 425 (see
In one example, the base plate 604 is constructed to operate as a heat sink and may comprise heat dissipating elements, such as one or more fins 608. The lighting module 520, 530 (see
The thermal interface 602 may be constructed as a plate of any suitable shape and with a thickness to provide sufficient mechanical strength to support lighting module. In particular, the thermal interface 602 may provide one or more fasteners and/or threaded surfaces (not shown) to engage and support the optical element 512. The thermal interface 602 may be constructed from any suitable material that provides desired thermal and electrical conductivities.
A self-contained lighting module 520, 530 (see
In one example, the one or more reflectors 704 have a frustoconical shape that is aligned concentrically with the center of the LED array 504. In another example, the one or more reflectors 704 may comprise a plurality of reflective segments corresponding to segments of a frustum of a cone. The one or more of reflectors 704 may comprise a generally flat, parabolic or irregularly-shaped surface. The one or more reflectors 704 may modify a light distribution pattern 425 (see
In some embodiments, the one or more reflectors 704 may be adapted to provide a light absorbing surface. In some embodiments, the one or more reflectors 704 are provided as reflective areas of a frustoconical protective screen that may be clear or opaque in areas that are not reflective. A dome or flattened lens 712 may be provided to complete the protective outer shell. The lens 712 may optically transform light passing through it, or the lens 712 may conduct light with minimum diffraction and/or attenuation. The lens 712 may comprise an optical block 714 that reduces the occurrence of hotspots and other artifacts in the light distribution pattern 425 (see
In some embodiments, the heat sink 802 may be replaced by an adaptor plate (not shown) that attaches the lighting module 520, 530 (see
The one or more reflectors 904 or one or more concentric layers of fins 924 may attach to an optional lens 712 that encloses the lighting module 520, 530 (see
In another example 1020, a passage 1004 connects to one or more passages 1002 provided in reflectors/fins 904/924. The one or more passages 1002 may form a heat pipe capable of efficiently transporting heat throughout the base plate 902 and the reflectors/fins 904/924. Convection airflow through the heat pipe formed by passages 1002, 1004 may transfer heat between the base plate 902 and the reflectors/fins 904/924.
The one or more reflectors 804, 904 (see
The fins 804, 824 (see
The various aspects of a street light are provided to enable one of ordinary skill in the art to practice the present disclosure. Various modifications to, and alternative configurations of, the street light presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other lighting applications. Thus, the claims are not intended to be limited to the various aspects of a street light presented throughout this disclosure, but are to be accorded the full scope consistent with the language of the claims. Thus, for example, lighting fixtures of any type, and for any lighting purpose, may be configured in accordance with the disclosure. All structural and functional equivalents to the elements of the various aspects of a light source described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.
This application claims the benefit and right of priority under 35 U.S.C. 119 to Provisional U.S. Patent Application No. 61/624,221, which was filed on Apr. 13, 2012.
Number | Date | Country | |
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61624221 | Apr 2012 | US |