Abstract:
A light emitting diode bulb includes: a socket base configured for insertion into a light fixture; a plurality of separate heat sinks attached to the socket base; light emitting diode elements mounted on the plurality of separate heat sinks; and an optical element covering one of the light emitting diode elements.

Description:
[0001]    This invention claims the benefit of U.S. Provisional Patent Application No. 61/646,583 filed on May 14, 2012, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the invention relate to the structure of an LED (light-emitting diode) bulb. More particularly, they relate to the structure of a heat sink within an LED bulb. Although the embodiments of the invention are suitable for a wide scope of applications, it is particularly suitable for more effective heat dissipation and heat isolation in multi-LED element light bulbs. 
         [0004]    2. Discussion of the Related Art 
         [0005]    In general, an LED light bulb includes one or more LED elements. An LED element produces illumination by turning a given amount of electric power into a certain amount of light. Electric power is typically measured in watts and the amount of light illumination is measured in lumens. An LED element converts electric power into light more efficiently than standard incandescent filament. LED bulbs are bright enough to replace incandescents. More specifically, an LED bulb producing the same number of lumens as a standard 60-watt incandescent bulb is only using twelve watts of power. In other words, a 60-watt incandescent bulb produces about 800 lumens of light just like a 12-watt LED bulb. 
         [0006]    Unlike an incandescent bulb that typically uses only a single light source, which is a filament, an LED bulb typically has a collection of a plurality of light sources in that each light source is an LED element. Thus, the collection of LED elements cumulatively produces the light emanating from a LED bulb. For example, a 12-watt LED bulb can be a collection of four 3-watt LED elements, three 4-watt LED elements or six 2-watt elements to produce 800 lumens of light. Each of the LED elements can include one or more LED chips. 
         [0007]    Although LED bulbs are much more efficient in converting electric power into light than incandescent bulbs, the LED elements still create heat. Further, an LED element can overheat so as to quit working, have severely shortened lifespan or incur damage that reduces power-to-light conversion efficiency. Higher wattage LED elements tend to be more efficient in converting electric power to light but also tend to be more susceptible to overheating. Thus, heat sink requirements for an individual LED element increases as the wattage capability for an LED element increases. 
         [0008]      FIG. 1  is a perspective view of a prior art LED bulb with multiple LED elements on a heat sink under a single dispersion lens. As shown in  FIG. 1 , an LED bulb  100  includes a socket base  101 . One end of the socket base  101  has a screw cap  102  for insertion into a light fixture. The other end of the socket base  101  opposite to the screw cap  102  has a base plate  103 . AC-to-DC conversion circuitry is housed within the socket base  101  between the screw cap  102  and the base plate  103 . 
         [0009]    The LED bulb  100  shown in  FIG. 1  also includes a heat sink  113  attached to the base plate  103 . The heat sink  113  can be attached by screws (not shown) that go through the screw holes  104  in the base plate  103  and screw into the heat sink  113  to fasten the heat sink  113  to the base plate  103 . The heat sink  113  can be metallic, such as Al or Cu. In the alternative, the heat sink  113  can be heat conductive ceramic, such as alumina. 
         [0010]    The LED bulb  100  shown in  FIG. 1  further includes LED elements  120   a - 120   d  mounted on the heat sink  113 . The wiring (not shown) for the LED elements  120   a - 120   d  passes through the heat sink  113  and through wiring holes  104  of the base plate  103  into the socket base  101 . The LED elements  120   a - 120   d  can each be an LED module with one or more LED chips within the LED module. In the case of LED modules as the LED elements  120   a - 120   d,  the modules can be permanently attached to the heat sink  113  by soldering (not shown) or removably attached to the heat sink  113  with screws (not shown). 
         [0011]    The LED bulb  100  shown in  FIG. 1  has a lens  130  overlying the LED elements  120   a - 120   d  on the heat sink  113 . The lens  130  can be a dispersion lens that disperses light from the LED elements  120   a - 120   d.  In the alternative, the lens  130  can be a conversion lens that focuses light from the LED elements  120   a - 120   d.  Both the dispersion lens and the conversion lens can include materials for light diffusion and/or have structural features for light refraction/diffusion purposes. The lens  130  can be made of a glass material, a polymer material or layers of such materials. 
         [0012]    The prior art LED bulb, as shown in  FIG. 1 , generally has at least four portions. The first portion is a socket part containing AC-to-DC conversion circuitry that is configured to screw into a light fixture. The second portion is a heat sink part attached to the socket part. The third portion is the LED elements, which can be LED modules, mounted on the heat sink part. The fourth portion is an optical element part above the LED elements to disperse or, alternatively, focus light from the LED elements. The LED elements is the portion that typically has a failure in the prior art LED bulb. 
         [0013]    A single LED element, such as an LED module, of a prior art LED bulb can fail. Further, a failing LED element of a prior art LED bulb tends to overheat and accelerate the failure of other LED elements on the heat sink. Replacing a single LED module in an LED bulb is more cost effective than replacing the entire LED bulb. An LED module can be replaced in a prior art LED bulb by removing the optical element and replacing a module that is removably attached to the heat sink  113 . However, a removably attached LED module has less thermal conductivity to the heat sink  113  than an LED module permanently attached to the heat sink. 
       SUMMARY OF THE INVENTION 
       [0014]    Accordingly, embodiments of the invention is directed to a solid state power source with frames for attachment to an electronic circuit that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
         [0015]    An object of embodiments of the invention is to provide an LED bulb with a modular heat sink structure. 
         [0016]    Another object of embodiments of the invention is to provide improved heat dissipation for LED elements in an LED light bulb. 
         [0017]    Another object of embodiments of the invention is to provide thermal isolation between LED elements in an LED light bulb. 
         [0018]    Additional features and advantages of embodiments of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of embodiments of the invention. The objectives and other advantages of the embodiments of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
         [0019]    To achieve these and other advantages and in accordance with the purpose of embodiments of the invention, as embodied and broadly described, a light emitting diode bulb includes: a socket base configured for insertion into a light fixture; a plurality of separate heat sinks attached to the socket base; light emitting diode elements mounted on the plurality of separate heat sinks; and an optical element covering one of the light emitting diode elements. 
         [0020]    In another aspect, the light emitting diode bulb includes: a socket base configured for insertion into a light fixture; a plurality of spaced-apart heat sinks on the socket base; light emitting diode elements mounted on the plurality of spaced-apart heat sinks; and lenses respectively mounted on the plurality of spaced-apart heat sinks. 
         [0021]    In yet another aspect, the light emitting diode bulb includes: a socket base configured for insertion into a light fixture; a plurality of spaced-apart heat sinks on the socket base; light emitting diode elements mounted on the plurality of spaced-apart heat sinks; optical elements respectively mounted on the plurality of spaced-apart heat sinks to cover the light emitting diode elements; and a retention plate positioned across each of the plurality of spaced-apart heat sinks. 
         [0022]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of embodiments of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of embodiments of the invention. 
           [0024]      FIG. 1  is a perspective view of a prior art LED bulb with multiple LED elements on a heat sink under a single dispersion lens. 
           [0025]      FIG. 2  is a perspective view of an LED bulb with multiple LED elements that are each on an individual heat sink according to an embodiment of the invention. 
           [0026]      FIG. 3  is a front view of multiple LED elements that are each on an individual heat sink according to an embodiment of the invention. 
           [0027]      FIG. 4  is a perspective view of multiple LED elements that are each on an individual heat sink according to an embodiment of the invention. 
           [0028]      FIG. 5  is a perspective view of an LED bulb with multiple LED elements that are each on an individual heat sink and are each covered by a respective dispersion lens according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Reference will now be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like reference numerals in the drawings denote like elements. 
         [0030]      FIG. 2  is a perspective view of an LED bulb with multiple LED elements that are each on an individual heat sink according to an embodiment of the invention. As shown in  FIG. 2 , an LED bulb  200  according an embodiment of the invention includes a socket base  201 . One end of the socket base  201  has a screw cap  202  for insertion into a light fixture. Although the exemplary embodiment shown in  FIG. 2  illustrates a screw cap  202 , other plug types for light fixtures can be alternatively implemented for insertion into a light fixture on the base  201 . The other end of the socket base  201  opposite to the screw cap  202  has a base plate  203 . 
         [0031]    The LED bulb  200  shown in  FIG. 2  also includes separate heat sinks  213   a - 213   d  attached to the base plate  203 . The separate heat sinks  213   a - 213   d  can be respectively attached to the base plate  203  by screws (not shown) that go through the screw holes  204  in the base plate  203  and screw into the separate heat sinks  213   a - 213   d  to fasten each of the separate heat sinks  213   a - 213   d,  respectively, to the base plate  203 . The separate heat sinks  213   a - 213   d  can be metallic, such as Al or Cu. In the alternative, the separate heat sinks  213   a - 213   d  can be heat conductive ceramic, such as alumina. As shown in  FIG. 2 , each of the separate heat sinks  213   a - 213   d  can have fins  213   a - 213   d  for increasing the transmittance of heat from the respective separate heat sink into the air surrounding the LED bulb  200 . As shown in  FIG. 2 , each of the separate heat sinks  213   a - 213   d  generally has a triangular shape such that they can all be combined into a circular configuration. In the alternative, each of the separate heat sinks  213   a - 213   d  can generally have a rectangular shape such that they can all be combined into a larger rectangular-shaped configuration. 
         [0032]    The LED bulb  200  shown in  FIG. 2  further includes LED elements  220   a - 220   d  mounted on the separate heat sinks  213   a - 213   d , respectively. The wiring (not shown) for the LED elements  220   a - 220   d  passes through the separate heat sinks  213   a - 213   d,  respectively, and through wiring holes  204  of the base plate  203  into the socket base  201 . In the case of LED modules as the LED elements  220   a - 220   d,  the modules can be permanently attached to the separate heat sinks  213   a - 213   d,  respectively, by a thermal conductive adhesive, such as solder (not shown). In the alternative, the modules can be replaceably attached to the separate heat sinks  213   a - 213   d , respectively, by fasteners, such as screws (not shown). 
         [0033]    The LED bulb  200  shown in  FIG. 2  has lens mounts  230   a - 230   d  with lens  231   a - 231   d  overlying the LED elements  220   a - 220   d  on the separate heat sinks  213   a - 213   d,  respectively. Each of the lens  231   a - 231   d  can be a dispersion lens that disperses light from the LED elements  220   a - 220   d.  In the alternative, the lens  231   a - 231   d  can be a conversion lens that focuses light from the LED elements  220   a - 220   d . Both the dispersion lens and the conversion lens can include materials for light diffusion and/or have structural features for light refraction/diffusion purposes. The lens  231   a - 231   d  can be made of a glass material, a polymer material or layers of such materials. The lens mounts  230   a - 230   d  can be metallic, such as Al or Cu. A metallic lens mount can act as another heat sink for the LED element. In the alternative, the lens mounts  230   a - 230   d  can be a polymer. 
         [0034]    Embodiments of the invention include the LED elements  220   a - 220   d  shown in  FIG. 2  being energized simultaneously or, alternatively, having stages of lighting brightness. For example, the LED bulb  200  can be three-way bulb in that LED element  220   a  comes on in a first stage, LED elements  220   b  and  220   c  come on in a second stage and LED elements  220   a - 220   d  come on in a third stage. In another example, the LED bulb  200  can be three-color bulb in that LED elements  220   a  and  220   d  comes on in a first stage as red light, LED elements  220   b  and  220   c  come on in a second stage as green light and LED elements  220   a - 220   d  come on in a third stage to make yellow light. 
         [0035]      FIG. 3  is a front view of multiple LED elements that are each on an individual heat sink according to an embodiment of the invention. As shown in  FIG. 3 , the separate heat sinks  213   a - 213   d  are space-apart from one another. By spacing the separate heat sinks  213   a - 213   d  apart from one another, air AF can flow between and through the spaced-apart heat sinks  213   a - 213   d . The air AF flowing or moving between or through the spaced-apart heat sinks  213   a - 213   d  increases the transmission of heat from the spaced-apart heat sinks  213   a - 213   d  into the air. In addition, the spacing between the spaced-apart heat sinks  213   a - 213   d  isolates the spaced-apart heat sinks  213   a - 213   d  from one another. That is, heat from one of the spaced-apart heat sinks  213   a - 213   d  is not transferred directly to the other spaced-apart heat sinks  213   a - 213   d . The holes  214  in each of the spaced-apart heat sinks  213   a - 213   d  are screw holes. 
         [0036]    As shown in  FIG. 3 , one or more LED chips  221   a - 221   d  can be on the LED elements  220   a - 220   d  within the lens mounts  230   a - 230   d.  Although  FIG. 3  shows four LED chips on each of the LED elements  220   a - 220   d,  each of the LED elements  220   a - 220   d  can alternatively contain just two LED chips, three LED chips or any number of LED chips in an array. In another alternative, the LED elements  220   a - 220   d  can have a different number of LED chips. Usually each of LED elements  220   a - 220   d  has the same amount of light output but the LED elements  220   a - 220   d  can be configured such that the LED elements  220   a - 220   d  each emit different amounts of light buy using different light elements. 
         [0037]      FIG. 4  is a perspective view of multiple LED elements that are each on an individual heat sink according to an embodiment of the invention. As shown in  FIG. 4 , the lens mounts  230   a - 230   d  are fastened onto the spaced-apart heat sinks  213   a - 213   d  with screw sets  232   a - 232   d,  respectively. Gaskets  233   a - 233   d  can be provided between the lens mounts  230   a - 230   d  and the spaced-apart heat sinks  213   a - 213   d , respectively. The gaskets  233   a - 233   d  provide weatherproof seals between the lens mounts  230   a - 230   d  and the spaced-apart heat sinks  213   a - 213   d , respectively. By removing one of the screw sets  232   a - 232   d  for one of the lens mounts  230   a - 230   d , that one of the LED elements  220   a - 220   d  can be replaced to affect a repair. 
         [0038]    A retention plate  215  is shown in  FIG. 4  positioned across each of the spaced-apart heat sinks  213   a - 213   d.  The screws  216   a - 216   d  attach the retention plate  215  onto the spaced-apart heat sinks  213   a - 213   d  through the screw holes  214  shown in  FIG. 3 . The retention plate  215  maintains the spacing relationship of the spaced-apart heat sinks  213   a - 213   d.    
         [0039]      FIG. 5  is a perspective view of an LED bulb with multiple LED elements that are each on an individual heat sink and are each covered by a respective dispersion lens according to an embodiment of the invention. As shown in  FIG. 5 , AC-to-DC conversion circuitry  206  is housed within the socket base  201  between the screw cap  202  and the base plate  203 . The spaced-apart heat sink  213   a  is mounted on the base plate  203  by screw set  217   a  through holes  204  in the base plate  203 . An LED element  220   a  is mounted on the spaced-apart heat sink  213   a.  A lens mounts  230   a  with a lens  231   a  is fastened onto the spaced-apart heat sink  213   a  with screw set  232   a.  The spaced-apart heat sink  213   a  is attached to the retention plate  215  with the screw  216   a.    
         [0040]    In embodiments of the invention, the LED bulb  200  can have an LED element repaired by replacement of the LED element together with the heat sink on which the LED element is positioned along with the lens mounts having a lens overlying the LED element. For example, the LED element  220   a  mounted on the spaced-apart heat sink  213   a  along with the lens mounts  230   a  having a lens  231   a  can be repaired by replacement. Such a repair includes removing the screw set  217   a  and screw  216   a,  and then removing the spaced-apart heat sink  213   a  with the LED element  220   a.  Subsequently, another spaced-apart heat sink with an LED element can be positioned on the base plate  203  but below the retention plate  215 , and then the screw set  217   a  and screw  216   a  are reinstalled. 
         [0041]    Replacing LED elements in a LED bulb by replacing both the LED element and the heat sink upon which the LED element is positioned not only enables repair by replacement of failing portions of the bulb but also isolates overheating LED elements from other LED elements of the LED bulb. The spaced-apart heat sinks enable air flow that increase the cooling capability of the spaced-apart heat sinks. The LED elements can be attached to a spaced-apart heat sink so as to maximize heat transference from the LED elements to the spaced-apart heat sink. 
         [0042]    It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the invention without departing from the spirit or scope of the invention. Thus, it is intended that embodiments of the invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.