Patent Publication Number: US-7901112-B2

Title: Lap based in light-emitting diodes

Description:
FIELD OF INVENTION 
     The present invention relates to a lamp based on at least one light-emitting diode. 
     BACKGROUND OF INVENTION 
     Fluorescent lamps are common. A fluorescent lamp is substantially a gas discharge tube with a fluorescent material coated on an internal side thereof and argon filled therein. Neon or krypton may additionally be filled in the fluorescent lamp. The pressure in the fluorescent lamp is about 0.3% of that in the atmosphere. A small amount of mercury is filled in the fluorescent lamp to provide silver vapor. The amount of the silver atoms is about 1/1000 of that of all gas atoms. Electricity is directed through the fluorescent lamp to cause gas discharge. The gas discharge causes the mercury vapor to emit ultraviolet light with average wavelength of 2534 angstroms. About 60% of the electricity is converted to the ultraviolet light. The other electricity is converted to heat that is dissipated. The fluorescent material converts about 40% of the ultraviolet light to visible light. Therefore, the efficiency of the fluorescent lamp is about 24% (60%×40%), roughly twice as high as that of a typical tungsten light bulb. 
     As discussed above, the efficiency of a fluorescent lamp is low, and the life of a fluorescent lamp is short. As energy is running out while pollution is getting worse, it is important to increase the efficiencies and lives of devices as well as exploit so called “green” energy. There is a trend to use light-emitting diodes instead of the fluorescent lamps because the light-emitting diodes consume less energy, last longer, work more stably and efficiently than the fluorescent lamps. 
     However, a light-emitting diode generates a lot of heat while emitting light. A light-emitting diode will have to operate at a high temperature for a long time if it is used instead of a fluorescent lamp. The quality of the light-emitting diode will deteriorate so that the life will be reduced. Moreover, the efficiency of the light-emitting diode will drop so that the luminance will be reduced. Light-emitting diodes will be more popular if the problems associated with the heat are solved. 
     In a lamp, light-emitting diodes are provided in a tube with a rough internal side for scatter light emitted from the light-emitting diodes. The efficiency of this lamp is low. 
     In another lamp, light-emitting diodes and radiators are provided in a tube so that the radiators dissipate heat generated with the light-emitting diodes. The large amount of the light-emitting diodes however entails a high cost in manufacturing and a high cost in operation. 
     The present invention is therefore intended to obviate or at least alleviate the problems encountered in prior art. 
     SUMMARY OF INVENTION 
     It is an objective of the present invention to provide an inexpensive lamp. 
     It is another objective of the present invention to provide an efficient lamp. 
     It is still another objective of the present invention to provide a durable lamp. 
     According to the present invention, the lamp includes a tube, a reflector, at least one illuminator unit, at least one radiator and two connectors. The tube is made of a transparent material. A reflector is disposed in the tube. The illuminator unit includes at least one light-emitting diode for emitting light. The radiator includes a first reduced portion inserted in the tube, a second reduced portion located opposite to the first reduced portion and fins for dissipating heat generated by the light-emitting diode. The first reduced portion of the radiator is formed with a face for supporting the illuminator unit so that the light-emitting diode can cast the light to the reflector that can reflect the light. The connectors are connected to the illuminator unit for conducting electricity to the illuminator unit from a power supply. 
     Other objectives, advantages and features of the present invention will become apparent from the following description referring to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will be described via the detailed illustration of the preferred embodiment referring to the drawings. 
         FIG. 1  is a perspective view of a lamp according to the preferred embodiment of the present invention. 
         FIG. 2  is an exploded view of the lamp shown in  FIG. 1 . 
         FIG. 3  is an enlarged partial side view of the lamp shown in  FIG. 2 . 
         FIG. 4  is an enlarged partial cross-sectional view of the lamp shown in  FIG. 3 . 
         FIG. 5  is another cross-sectional view of the lamp shown in  FIG. 4 . 
         FIG. 6  is side view of the lamp shown in  FIG. 1 . 
         FIG. 7  is an enlarged cross-sectional view of the lamp of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 through 3 , a lamp include a tube  10 , two radiators  20 , two electric connectors  30  and two illuminator units  40  according to the preferred embodiment of the present invention. The tube  10  is made of a transparent material such as glass and acrylic. Referring to  FIGS. 4 and 5 , two ribs  11  are formed on an internal side of the tube  10  and a reflector  15  supported on the ribs  11 . The reflector  15  includes a bent form as particularly shown in  FIG. 5 . The reflector  15  may include an arched form in another embodiment. Furthermore, the reflector  15  may be replaced with a reflector coating on the internal side of the tube  10  and the ribs  11  be omitted in another embodiment. 
     The radiators  20  are made of a radiating material such as aluminum. Each of the radiators  20  includes fins  21  formed on an external side, i.e., the periphery. The fins  21  are used to dissipate heat generated by the illuminator units  40  to the environment. Each of the radiators  20  includes a first reduced portion  22  formed at an end, a second reduced portion  25  formed at an opposite end and a cavity  23  defined in the first reduced portion  22 . The first reduced portion  22  is inserted in a related end of the tube  10 . The second reduced portion  25  is inserted in a related one of the connectors  30 . 
     The cavity  23  is defined by a planar face  24  and a conical face. If the tube  10  is laid horizontally, the axis of the conical face will be located horizontally while a line perpendicular to the planar face  24  is biased upwards from a horizontal line. 
     Each of the illuminator units  40  includes light-emitting diodes  45  provided on a circuit board. The circuit board is attached to the planar face  24  of a related one of the radiators  20 . 
     Each of the connectors  30  is connected to a related one of the illuminator units  40 . The connectors  30  can be connected to a power supply for energizing the illuminator units  40  with the power supply. 
     Referring to  FIGS. 6 and 7 , the light-emitting diodes  45  emits light towards the reflector  15  as indicated with a letter “A.” In turn, the reflector  15  reflects and scatters the light as indicated with a letter “B.” Thus, the light is used for illumination. 
     There are advantages of the lamp of the present invention over the lamps addressed in the BACKGROUND OF INVENTION. Firstly, the cost is low in the fabrication of the lamp because there are only a few light-emitting diodes  45 . Secondly, the efficiency of the operation of the lamp is constant because the radiators  20  prevent heat from accumulating in the lamp. Thirdly, the life of the lamp is long because overheating of the lamp is prevented. 
     The present invention has been described via the detailed illustration of the preferred embodiment. Those skilled in the art can derive variations from the preferred embodiment without departing from the scope of the present invention. Therefore, the preferred embodiment shall not limit the scope of the present invention defined in the claims.