Patent Publication Number: US-8974091-B2

Title: Heat-dissipating structure for an LED lamp

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a heat-dissipating structure and, more particularly, to a heat-dissipating structure for an LED (light-emitting diode) lamp. 
     2. Description of the Related Art 
     To cope with global energy depletion, the government of every country stipulates different policies advocating for energy conservation. In response to the call, LED appears to be the lighting element receiving the most attention recently. Many electronic appliances developed with LED, such as LED televisions, LED lamps and the like, are widely favored by consumers. 
     The development of LED lamps has become increasingly mature in recent years, and LED lamps are commonplace everywhere. Regular families prefer LED bulbs more, because users can perfectly mount the LED bulbs in the original light bulb sockets without replacing the original lamp set, thereby saving users&#39; effort and expense. 
     When LEDs are powered on to emit light, considerable heat is generated. If not quickly dissipated, the heat will be accumulated. The temperature rise caused by the accumulated heat will destroy the LEDs. To tackle such issue, manufacturers of LED lamps attempt to improve the heat dissipation by changing the structure of the LED lamps externally. With reference to  FIGS. 5 and 6 , a conventional LED lamp has a light source substrate  90 , a power conversion device  91 , a heat sink  92  mounted around the light source substrate  90  and the power on a lower end of the heat sink  92  and has multiple LEDs  95  mounted on a bottom thereof. The power conversion device  91  is mounted on an upper end of the heat sink  92  and is electrically connected to a mains power and the light source substrate  90 . The top cover  93  is mounted on a top opening of the heat sink  92  to seal the power conversion device  91 . The chamber  94  is defined between the light source substrate  90  and the power conversion device  91 . When the LEDs on the light source substrate  90  are lit and generate heat, the chamber  94  above the light source substrate  90  accumulates heat. Moreover, the power conversion device  91  also generates heat when converting the AC power into DC power. It is the heat sink  92  that quickly dissipates the heat generated from the light source substrate  90  and the power conversion device  91  outside of the LED lamp. 
     Although the conventional LED lamp can dissipate heat through the heat sink  92 , it is more likely than not that the heat generated by the light source substrate  90  and the power conversion device  91  still accumulates in the chamber  94  to cause a high temperature rise as the heat sink  92  only contacts peripheries of the light source substrate  90  and the power conversion device  91 . If the accumulated heat inside the chamber  94  is not dissipated soon enough, the light source substrate  90  or the power conversion device  91  can be easily damaged. Besides, the heavy heat sink  92  also causes inconvenience in assembly of the LED lamp. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a heat-dissipating structure for an LED lamp capable of rapidly dissipating heat through a heat convection effect. 
     To achieve the foregoing objective, the heat-dissipating structure for an LED lamp has a lamp cover, a ceramic substrate and a power conversion device. 
     The lamp cover has a peripheral wall, multiple heat-dissipating holes and multiple mounting ears. The heat-dissipating holes are formed through the peripheral wall. 
     Each mounting ear is formed on an edge of one of the heat-dissipating holes, and is bent inwardly with the heat-dissipating hole uncovered. 
     The ceramic substrate is mounted inside the lamp cover, is securely mounted on the mounting ears, and has multiple light-emitting diodes (LEDs) mounted thereon. 
     The power conversion device is mounted on the lamp cover, faces the ceramic substrate, and is electrically connected to the LEDs on the ceramic substrate. 
     An LED lamp having the foregoing heat-dissipating structure acquires the mains power through the power conversion device and transmits the converted power to the ceramic substrate so that each LED on the ceramic substrate is turned on to emit light. The heat generated when each LED emits light is first absorbed by the ceramic substrate, and the remaining heat is conducted to the mounting ears and the entire lamp cover. The heat absorbed by the ceramic substrate and generated when the power conversion device converts the mains power is transferred to the heat convection space, which is defined between the ceramic substrate and the lamp cover, through the heat convection effect and is further dissipated to ambient air around the LED lamp through the heat-dissipating holes of the lamp cover. Accordingly, the heat generated when the LEDs are lit and when the power conversion device converts the mains power is not accumulated and can be quickly dissipated. Also, since the lamp cover has no heat sink or other heat-dissipating module mounted thereon, the LED lamp is light in weight. 
     Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of an embodiment of a heat-dissipating structure for an LED lamp in accordance with the present invention; 
         FIG. 2  is a side view in partial section of the heat-dissipating structure for the LED lamp in  FIG. 1 ; 
         FIG. 3  is an operational side view in partial section of the heat-dissipating structure for the LED lamp in  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of another embodiment of a heat-dissipating structure for the LED lamp in accordance with the present invention; 
         FIG. 5  is a perspective view of a conventional LED lamp; and 
         FIG. 6  is a side view in partial section of the conventional LED lamp. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , an embodiment of a heat-dissipating structure for a lamp in accordance with the present invention has a lamp cover  10 , a power conversion device  20  and a ceramic substrate  30 . 
     The lamp cover  10  is funnel-shaped and has multiple heat-dissipating holes  11  and multiple mounting ears  12 . The heat-dissipating holes  11  are formed through a peripheral wall of the lamp cover  10 . Each mounting ear  12  is formed on an edge of one of the heat-dissipating holes  11 , is bent inwardly with the corresponding heat-dissipating hole  11  uncovered, and has a through hole  121  formed through the mounting ear  12 . In the present embodiment, the lamp cover  10  is made of an aluminum material. 
     The power conversion device  20  is mounted inside a power cap  21 , is located inside the lamp cover  10 , and converts AC power acquired from the mains power into DC power as an operating power to the LED lamp. The power cap  21  has a cable hole  22  formed through the power cap  21  for at least one power cable  23  to penetrate through the power cap  21 , and is electrically insulating to avoid the risk of electric shock. 
     The ceramic substrate  30  is mounted inside the lamp cover  10 , is securely connected with the mounting ears  12 , faces the power conversion device  20 , and has an air passage hole  32 , multiple threaded holes  31 , multiple bolts  33  and multiple LEDs  35 . The air passage hole  32  is centrally formed through the ceramic substrate  30 . Each threaded hole  31  is formed through the ceramic substrate  30  to correspond to the through hole  121  of a corresponding mounting ear  12 . Each bolt  33  is mounted through one of the threaded holes  31  of the ceramic substrate and the through hole  121  of a corresponding mounting ear  12  and is screwed with a nut  34 . The LEDs  35  are mounted on the ceramic substrate  30 . In the present embodiment, the ceramic substrate  30  is made of a ceramic material, has a good heat-dissipating capability, and is electrically insulating, thereby avoiding power to be transmitted to the lamp cover  10  through the ceramic substrate  30  and the risk of electric shock. With reference to  FIG. 2 , the power conversion device  20  is connected to the ceramic substrate  30  through the at least one power cable  23 . The at least one power cable  23  penetrates through the cable hole  22  on the power cap  21 . Except the junction of the at least one power cable  23  and the ceramic substrate  30 , the rest of the portion of the at least one power cable  23  is sheathed with an insulating layer for the purpose of electric insulation to avoid the risk of shock due to users&#39; advertent contact. 
     An LED lamp having the foregoing heat-dissipating structure acquires the mains power through the power conversion device  20  and transmits the converted power to the ceramic substrate  30  through the at least one power cable  23  so that each LED  35  on the ceramic substrate  30  is turned on to emit light. Since the ceramic substrate  30  is made of a ceramic material and thus has an optimal heat-dissipating effect and since the mounting ears  12  contact the ceramic substrate  30 , the heat generated when each LED emits light is first absorbed by the ceramic substrate  30 , and the remaining heat is conducted to the mounting ears  12  and the entire lamp cover  10 . The heat on the lamp cover  10  is transferred to ambient air. A heat convection space  40  is defined between the ceramic substrate  30  and the lamp cover  10 . With reference to  FIG. 3 , the heat absorbed by the ceramic substrate  30  is transferred to the heat convection space  40  through a heat convection effect and is further dissipated to ambient air around the LED lamp through the heat-dissipating holes  11 . The heat generated when the power conversion device  20  converts the mains power into DC power may be absorbed by the power cap  21 . Similarly, the heat absorbed by the power cap  21  is transferred to the heat convection space  40  through a heat convection effect and is further dissipated to ambient air around the LED lamp through the heat-dissipating holes  11  of the lamp cover  10  and the air passage hole  32  of the ceramic substrate  30 . Accordingly, the heat generated when the LEDs are lit and when the power conversion device converts the mains power is not accumulated and can be quickly dissipated. As the lamp cover  10  has no heat sink or other heat-dissipating module mounted thereon, the LED lamp is light in weight. 
     With reference to  FIG. 4 , another embodiment of a heat-dissipating structure for a lamp in accordance with the present invention is roughly the same as the foregoing embodiment, and has a power conversion device  20  and a ceramic substrate  30  mounted on a lamp cover  10 ′. The lamp cover  10 ′ has multiple heat-dissipating holes  11 ′ and multiple mounting ears  12 ′ formed on a peripheral wall of the lamp cover  10 ′. The ceramic substrate  30  is mounted on the mounting ears  12 ′ of the lamp cover  10 ′. The present embodiment differs from the foregoing embodiment in that the heat-dissipating holes  11 ′ differ from those of the foregoing embodiment in terms of number, shape, size and location, so that the air circulation between the air in a heat convection space  40  defined between the ceramic substrate  30  and the lamp cover  10 ′ and external air in the ambient environment can be tailored to customers&#39; requirements. As the thermal contact area between each mounting ear  12 ′ and the ceramic substrate  30  can also differ from that in the foregoing embodiment in terms of shape and size, heat can be dissipated in a desired speed. Additionally, the lamp cover  10 ′ can be tailored to have a customized shape depending on consumers&#39; demands to adapt to different environments and achieve to be aesthetically attractive. 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.