Abstract:
A light emitting apparatus includes a housing having a transparent portion, at least one LED positioned within the housing to emit light through the transparent portion, and a fan positioned within the housing to cool said at least one LED.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. Nonprovisional patent application Ser. No. 12/334,282, entitled “LIGHT EMITING DIODE LAMP,” which was filed on Dec. 12, 2008, the entirety of which is herein incorporated by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to light emitting devices, and more particularly to light emitting diode lamps. 
       BACKGROUND 
       [0003]    Light emitting diodes (LEDs) are attractive candidates for replacing conventional light sources such as incandescent and fluorescent lamps. LEDs have substantially higher light conversion efficiencies than incandescent lamps and longer lifetimes than both types of conventional light sources. In addition, some types of LEDs now have higher conversion efficiencies than fluorescent light sources and still higher conversion efficiencies have been demonstrated in the laboratory. Finally, LEDs require lower voltages than fluorescent lamps, and therefore, provide various power saving benefits. 
         [0004]    Despite the advantages of using LEDs as light sources, consumer acceptance will depend largely on the adaptability of these sources into existing lighting fixtures using conventional light sources (e.g., incandescent or fluorescent lamps). LED light sources designed for direct replacement of conventional light sources could be instrumental in accelerating consumer acceptance, and thereby, revolutionize the lighting industry. Unfortunately, there exists significant challenges in designing LED light sources that directly replace existing light sources, such as the incandescent light bulb for example. 
       SUMMARY 
       [0005]    In one aspect of the disclosure, a light emitting apparatus includes a housing having a transparent portion, at least one LED positioned within the housing to emit light through the transparent portion, and a fan positioned within the housing to cool said at least one LED. 
         [0006]    In another aspect of the disclosure, a light emitting apparatus includes at least one LED configured to emit light, a housing having means for transmitting the light emitted by said at least one LED, and means, positioned within the housing, for cooling said at least one LED. 
         [0007]    In a further aspect of the disclosure, light emitting apparatus includes at least one LED configured to emit light, a housing containing said at least one LED, wherein the housing comprises a transparent portion positioned to transmit the light emitted from said at least one LED, and a fan positioned within the housing to cool said at least one LED. 
         [0008]    It is understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein it is shown and described only exemplary configurations of an LED lamp by way of illustration. As will be realized, the present invention includes other and different aspects of an LED lamp and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and the detailed description are to be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0009]    Various aspects of the present invention are illustrated by way of example, and not by way of limitation, in the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a conceptual cross-sectional view illustrating an example of an LED; 
           [0011]      FIG. 2  is a conceptual cross-sectional view illustrating an example of an LED with a phosphor layer; 
           [0012]      FIG. 3A  is a conceptual top view illustrating an example of an LED array; 
           [0013]      FIG. 3B  is a conceptual cross-sectional view of the LED array of  FIG. 3A ; 
           [0014]      FIG. 4A  is a conceptual top view illustrating an example of an alternative configuration of an LED array; 
           [0015]      FIG. 4B  is a conceptual cross-sectional view of the LED array of  FIG. 4A ; and 
           [0016]      FIG. 5  is a conceptual side view of an LED lamp; 
           [0017]      FIG. 6  is a exploded side view of the LED lamp of  FIG. 5 ; and 
           [0018]      FIG. 7  is a conceptual side view of another configuration of an LED lamp. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    The present invention is described more fully hereinafter with reference to the accompanying drawings, in which various aspects of the present invention are shown. This invention, however, may be embodied in many different forms and should not be construed as limited to the various aspects of the present invention presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. The various aspects of the present invention illustrated in the drawings may not be drawn to scale. Rather, the dimensions of the various features may be expanded or reduced for clarity. In addition, some of the drawings may be simplified for clarity. Thus, the drawings may not depict all of the components of a given apparatus (e.g., device) or method. 
         [0020]    Various aspects of the present invention will be described herein with reference to drawings that are schematic illustrations of idealized configurations of the present invention. As such, variations from the shapes of the illustrations as a result, for example, manufacturing techniques and/or tolerances, are to be expected. Thus, the various aspects of the present invention presented throughout this disclosure should not be construed as limited to the particular shapes of elements (e.g., regions, layers, sections, substrates, etc.) illustrated and described herein but are to include deviations in shapes that result, for example, from manufacturing. By way of example, an element illustrated or described as a rectangle may have rounded or curved features and/or a gradient concentration at its edges rather than a discrete change from one element to another. Thus, the elements illustrated in the drawings are schematic in nature and their shapes are not intended to illustrate the precise shape of an element and are not intended to limit the scope of the present invention. 
         [0021]    It will be understood that when an element such as a region, layer, section, substrate, or the like, is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. It will be further understood that when an element is referred to as being “formed” on another element, it can be grown, deposited, etched, attached, connected, coupled, or otherwise prepared or fabricated on the other element or an intervening element. 
         [0022]    Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element&#39;s relationship to another element as illustrated in the drawings. It will be understood that relative terms are intended to encompass different orientations of an apparatus in addition to the orientation depicted in the drawings. By way of example, if an apparatus in the drawings is turned over, elements described as being on the “lower” side of other elements would then be oriented on the “upper” side of the other elements. The term “lower”, can therefore, encompass both an orientation of “lower” and “upper,” depending of the particular orientation of the apparatus. Similarly, if an apparatus in the drawing is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The terms “below” or “beneath” can, therefore, encompass both an orientation of above and below. 
         [0023]    Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and this disclosure. 
         [0024]    As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The term “and/or” includes any and all combinations of one or more of the associated listed items 
         [0025]    Various aspects of an LED lamp will now be presented. However, as those skilled in the art will readily appreciate, these aspects may be extended to other light sources without departing from the invention. The LED lamp may be configured as a direct replacement for conventional light sources, including, by way of example, incandescent, fluorescent, halogen, quartz, high-density discharge (HID), and neon lamps or bulbs. In these configurations, one or more LEDs may be mounted with a fan in a housing. The housing may have a transparent portion for transmitting light emitted by the LEDs. The LED is well known in the art, and therefore, will only briefly be discussed to provide a complete description of the invention. 
         [0026]      FIG. 1  is a conceptual cross-sectional view illustrating an example of 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, and is referred respectively as n-type or p-type semiconductor regions. Referring to  FIG. 1 , the LED  100  includes an n-type semiconductor region  104  and a p-type semiconductor region  108 . A reverse electric field is created at the junction between the two regions, which cause the electrons and holes to move away from the junction to form an active region  106 . When a forward voltage sufficient to overcome the reverse electric field is applied across the p-n junction through a pair of electrodes  110 ,  112 , electrons and holes are forced into the active region  106  and recombine. When electrons recombine with holes, they fall to lower energy levels and release energy in the form of light. 
         [0027]    In this example, the n-type semiconductor region  104  is formed on a substrate  102  and the p-type semiconductor region  108  is formed on the active layer  106 , however, the regions may be reversed. That is, the p-type semiconductor region  108  may be formed on the substrate  102  and the n-type semiconductor region  104  may formed on the active layer  106 . As those skilled in the art will readily appreciate, the various concepts described throughout this disclosure may be extended to any suitable layered structure. Additional layers or regions (not shown) may also be included in the LED  100 , including but not limited to buffer, nucleation, contact and current spreading layers or regions, as well as light extraction layers. 
         [0028]    The p-type semiconductor region  108  is exposed at the top surface, and therefore, the p-type electrode  112  may be readily formed thereon. However, the n-type semiconductor region  104  is buried beneath the p-type semiconductor layer  108  and the active layer  106 . Accordingly, to form the n-type electrode  110  on the n-type semiconductor region  104 , a cutout area or “mesa” is formed by removing a portion of the active layer  106  and the p-type semiconductor region  108  by means well known in the art to expose the n-type semiconductor layer  104  therebeneath. After this portion is removed, the n-type electrode  110  may be formed. 
         [0029]      FIG. 2  is a conceptual cross-sectional view illustrating an example of a LED with a phosphor layer. In this example, a phosphor layer  202  is formed on the top surface of the LED  100  by means well known in the art. The phosphor layer  202  converts a portion of the light emitted by the LED  100  to light having a different spectrum from that emitted from the LED  100 . A white LED light source can be constructed by using an LED that emits light in the blue region of the spectrum and a phosphor that converts blue light to yellow light. A white light source is well suited as a replacement lamp for conventional light sources, however, the invention may be practiced with other LED and phosphor combinations to produce different color lights. The phosphor layer  202  may include, by way of example, phosphor particles suspended in a carrier or be constructed from a soluble phosphor that is dissolved in the carrier. 
         [0030]    In a configuration of an LED lamp, an LED array may be used to provide increased luminance.  FIG. 3A  is a conceptual top view illustrating an example of an LED array, and  FIG. 3B  is a conceptual cross-sectional view of the LED array of  FIG. 3A . In this example, a number of phosphor-coated LEDs  300  may be formed on a substrate  302  by means well known in the art. The bond wires (not shown) extending from the LEDs  300  may be connected to traces (not shown) on the surface of the substrate  302 , which connect the LEDs  300  in a parallel and/or series fashion. Typically, the LEDs  300  may be connected in parallel streams of series LEDs with a current limiting resistor (not shown) in each stream. The substrate  302  may be any suitable material that can provide support to the LEDs  300  and can be mounted within a housing (not shown). 
         [0031]      FIG. 4A  is a conceptual top view illustrating an example of an alternative configuration of an LED array, and  FIG. 4B  is a conceptual cross-sectional view of the LED array of  FIG. 4A . In a manner similar to that described in connection with  FIGS. 3A and 3B , a substrate  302  designed for mounting in a housing (not shown) may be used to support an array of LEDs  400 . However, in this configuration, a phosphor layer is not formed on each individual LED. Instead, phosphor  401  is deposited within a cavity  402  bounded by an annular ring  404  that extends circumferentially around the outer surface of the substrate  302 . The annular ring  404  may be formed by boring a cylindrical hole in a material that forms the substrate  302 . Alternatively, the substrate  302  and the annular ring  404  may be formed with a suitable mold, or the annular ring  404  may be formed separately from the substrate  302  and attached to the substrate using an adhesive or other suitable means. In the latter configuration, the annular ring  404  is generally attached to the substrate  302  before the LEDs  400 , however, in some configurations, the LEDs  400  may be attached first. Once the LEDs  400  and the annular ring  404  are attached to the substrate  302 , a suspension of phosphor particles in a carrier may be introduced into the cavity  402 . The carrier material may be an epoxy or silicone, however, carriers based on other materials may also be used. The carrier material may be cured to produce a solid material in which the phosphor particles are immobilized. 
         [0032]      FIG. 5  is a conceptual side view of an LED lamp. The LED lamp  500  may include a housing  502  having a transparent portion  503  (e.g., glass, plastic, etc.) mounted onto a base  504 . The transparent portion  503  is shown with a substantially circular or elliptical portion  505  extending from a neck portion  507 , although the transparent portion  503  may take on other shapes and forms depending on the particular application. 
         [0033]    An LED array  506  positioned within the housing  502  may be used as a light source. The LED array  506  may take on various forms, including any one of the configurations discussed earlier in connection with  FIGS. 2-4 , or any other suitable configuration now known or developed in the future. Although an LED array is well suited for the LED lamp, those skilled in the art will readily understand that the various concepts presented throughout this disclosure are not necessarily limited to array and may be extended to an LED lamp with a single LED. 
         [0034]    A plate  508  anchored to the base  504  provides support for the LED array  506 . In one configuration of an LED lamp  500 , standoffs  510  extending from the plate  508  are used to separate the LED array  506  from the plate  508 . Examples include plastic standoffs with conical heads that can be pushed through holes in the substrate of the LED array  506  or hollow plastic standoffs with internal threads that allow the LED array to be mounted with screws. Other ways to mount the LED array  506  will be readily apparent to those skilled in the art from the teachings presented throughout this disclosure. The plate  508  may be constructed from any suitable insulting material, including by way of example, glass. 
         [0035]    A fan  512  may be used to cool the LED array  504 . A non-limiting example of a fan that is well suited for LED lamp applications is a RSDS solid-state fan developed by Thorrn Micro Technologies, Inc. The RSDS uses a series of live wires that produce an ion rich gas with free electrons for conducting electricity. The wires lie within uncharged conducting plates that are contoured into half-cylindrical shape to partially envelope the wires. Within the electric field that results, the ions push neutral air molecules from the wire to the plate, generating air flow. The fan  512  may be mounted to the substrate of the LED array  504  as shown in  FIG. 5 , but may be mounted elsewhere in the housing  502 . Those skilled in the art will be readily able to determine the location of the fan best suited for any particular application based on the overall design parameters. 
         [0036]    The plate  508  also provides a means for routing wires  514   a  and  514   b  from the LED array  504  to electrical contacts  516   a  and  516   b  on the base  510 . In one configuration of an LED lamp  500 , the wires  514   a  and  514   b  may be routed from the LED array  504  to the plate  512  through the plastic hollow standoffs previously described. In another configuration of an LED lamp  500 , the wires  514   a  and  514   b  themselves can be used to separate the LED array  504  from the plate  508 , thus eliminating the need for standoffs. In the latter configuration, the wires  514   a  and  514   b  may be spot welded to feedthrough holes in the plate  508  with another set of spot welded wires extending from the feedthrough holes to the electrical contacts  516   a  and  516   b  on the base  510 . 
         [0037]    The arrangement of electrical contacts  516   a  and  516   b  may vary depending on the particular application. By way of example, the LED lamp  500  may have a base  510  with a screw cap, as shown in  FIG. 5 , with one electrical contact  516   a  at the tip of the base  510  and the screw cap serving as the other electrical contact  516   b.  Contacts in the lamp socket (not shown) allow electrical current to pass through the base  510  to the LED array  504 . Alternatively, the base may have a bayonet cap with the cap used as an electrical contact or only as a mechanical support. Some miniature lamps may have a wedge base and wire contacts, and some automotive and special purpose lamps may include screw terminals for connection to wires. The arrangement of electrical contacts for any particular application will depend on the design parameters of that application. 
         [0038]    Power may be applied to the LED array  506  and the fan  512  through the electrical contacts  516   a  and  516   b.  An AC-DC converter (not shown) may be used to generate a DC voltage from a lamp socket connected to a wall-plug in a household, office building, or other facility. The DC voltage generated by the AC-DC converter may be provided to a driver circuit (not shown) configured to drive both the LED array  506  and the fan  512 . The AC-DC converter and the driver circuit may be located in the base  504 , on the LED array  506 , or anywhere else in the housing  502 . In some applications, the AC-DC converter may not be needed. By way of example, the LED array  506  and the fan  512  may be designed for AC power. Alternatively, the power source may be DC, such as the case might be in automotive applications. The particular design of the power delivery circuit for any particular application is well within the capabilities of one skilled in the art. 
         [0039]    An example of a process for manufacturing an LED lamp  500  will now be presented with reference to  FIG. 6 .  FIG. 6  is an exploded side view of the LED lamp  500  showing the individual dissembled elements of the LED lamp  500  in their proper relationship with respect to their assembled position. In this example, the disassembled elements include the transparent portion  503  of the housing, the plate  508 , and the base  504 . 
         [0040]    The LED lamp  500  may be assembled by mounting the LED array  506  and the fan  512  onto the plate  508  using standoffs  510  or some other suitable means. Once the LED array  506  and the fan  512  are mounted to the plate  508 , the plate may be attached to the neck  507  of the transparent portion  503  of the housing. The transparent portion  503  of the housing may be formed from plastic or glass (which is manufactured by feeding silica into a furnace) and shaped by placing the it in a mold to cure. In the case where the plate  508  is glass, the transparent portion  503  may be fused to the plate. The electrical wires  514   a  and  514   b  extending from the plate  508  may be connected to the electrical contacts  516   a  and  516   b , respectively, and then transparent portion  503  of the housing may be mounted to the base  504 . 
         [0041]      FIG. 7  is a conceptual side view of another configuration of an LED lamp. In this configuration, a housing  702  includes a transparent portion  704  in the shape of a tube with caps  706   a  and  706   b  at the ends. A number of LED arrays  708  may be distributed along a substrate  710  that extends across the tubular transparent portion  704  of the housing  702 . Alternatively, the substrate  710  may support a single LED array, or even a single LED. The various configurations of LEDs and LED arrays presented thus far are well suited for this LED lamp application, but other configurations may also be used. A number of RSD5 fans  712 , or other cooling devices, may also be distributed along the substrate, or located elsewhere, to cool the LED arrays  708 . Two electrical contacts  714 ′ and  714 ″ extend from one cap  706   a  and two electrical contacts  716 ′ and  716 ″ extend from the other cap  706   b.  The electrical contact arrangement allows the LED lamp to function as a direct replacement for conventional fluorescent lamps. 
         [0042]    Power may be applied between to the LED arrays  708  and the fans  712  through any pair of electrical contacts. By way of example, one of the electrical contacts  714 ′ on one cap  706   a  may be connected to a voltage source and one of the electrical contacts  716 ′ on the other cap  706   b  may be connected to the voltage return. In higher current applications, the voltage source may be connected to both electrical contacts  714 ′ and  714 ″ extending from one cap  706   a  and the voltage return may be connected to both electrical contacts  716 ′ and  716 ″ extending from the other cap  706   b.  An AC-DC converter (not shown) and driver (not shown) may be used to generate a DC voltage and drive the LED arrays  708  and fans  712 . The AC-DC converter and driver may be mounted onto the substrate  610  or located elsewhere in the LED lamp  700 . Alternatively, the AC-DC converter and/or driver may be mounted outside the lamp, either inside or outside of the light fixture. 
         [0043]    The various aspects of this disclosure are provided to enable one of ordinary skill in the art to practice the present invention. Various modifications to aspects presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other LED lamp configurations regardless of the shape or diameter of the glass enclosure and the base and the arrangement of electrical contacts on the lamp. By way of example, these concepts may be applied to bulb shapes commonly referred to in the art as A series, B series, C-7/F series, ER, G series, GT, K, P-25/PS-35 series, BR series, MR series, AR series, R series, RP-11/S series, PAR Series, Linear series, and T series; ED17, ET, ET-18, ET23.5, E-25, BT-28, BT-37, BT-56. These concepts may also be applied to base sizes commonly referred to in the art as miniature candela screw base E10 and E11, candela screw base E12, intermediate candela screw base E17, medium screw base E26, E26D, E27 and E27D, mogul screw base E39, mogul Pf P40s, medium skirt E26/50x39, candela DC bay, candela SC bay B15, BA15D, BA15S, D.C. Bayonet, 2-lug sleeve B22d, 3-lug sleeve B22-3, medium Pf P28s, mogul bi-post G38, base RSC, screw terminal, disc base, single contact, medium bi-post, mogul end prong, spade connector, mogul pre-focus and external mogul end prong; admedium skirted, medium skirted, position-oriented mogul, BY 22 D, Fc2, ceramic spade series (J, G, R), RRSC, RSC; single pin series, bi-pin series, G, GX, 2G series. Thus, the claims are not intended to be limited to the various aspects of this disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the elements of the various aspects 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. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”