Patent Publication Number: US-8115370-B2

Title: Bending LED bulb

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to an LED bulb, and more particularly to a bending LED bulb that can provide uniform luminance and dissipate out heat generated by LEDs. 
     2. Description of the Related Art 
     Ball-type bulbs and incandescent tubes for lighting purpose in early stage are all quite common. 
     In view of the awakening energy-saving consciousness, energy-saving bulbs, such as U-shaped bulb, 2C type bulb and helical bulb, have started their entry in the light market. In spite of being more energy-saving, LED bulbs with more energy-saving capability overwhelm the glamour of the earlier energy-saving bulbs to become the new favorite in the market after high power white light LED technique become mature. 
     With reference to  FIGS. 13 and 14 , a conventional LED ball-type bulb  30  has a base  31 , an LED substrate  32  and a glass cover  33 . 
     The base  31  has a free end, a base electrode  311  and a bottom electrode  312 . The base electrode  311  takes a form of threads formed around the base  31  for screwing into a screw lamp socket. The bottom electrode  312  is formed on a bottom of the base  31 . 
     The LED substrate  32  is securely mounted on an end of the base  31  opposite to the free end, and has a rigid circuit board  321 , a plurality of light-emitting diodes (LED)  322  and a heat sink  323 . The rigid circuit board  321  is electrically connected to the base electrode  311  and the bottom electrode  312 . The LEDs  322  are mounted on a top of the rigid circuit board  321  in a form of a matrix pattern. The heat sink is mounted on a bottom of the rigid circuit board  321 . The glass cover  33  is securely mounted on the base  31  to cover the LED substrate  32  therein. 
     As the candle (cd) of a bulb for lighting must reach a standard value, the LED bulb  30  needs to employ a plurality of LEDs, for example, as shown in  FIG. 14 , to meet that end. LED is well-known in consuming less power, yet a layout of the LEDs  322  ends up with a shorter life duration of the LED bulb  30  because of heat generated from the LEDs  322 . After a long term of operation, the accumulated heat escalate the temperature of the overall LED bulb  30 . In particular, the LEDs  322  that centrally located have a higher temperature than that of other LEDs  322  and are prone to damage. Hence, LED bulbs or tubes with similar LED layout have to be arranged with additional heat dissipation structure and this increases the cost for manufacturing the LED bulb  30 . 
     Furthermore, there are plenty of ball-type LED bulbs and LEDs tubes currently available in the marketplace, while energy-saving bending LED tubes haven&#39;t been absent in the market so far. If the heat dissipation issue of the LEDs can be solved, LED bulbs can be further promoted as the new-generation energy-saving lighting source. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a bending LED bulb providing uniform luminance and dissipating waste heat generated by LEDs. 
     To achieve the foregoing objective, the bending LED bulb has a transparent bending tube and at least one flexible LED strip. The transparent bending tube has two ends and at least one sealing end. The at least one sealing end is formed on at least one of the ends of the transparent bending tube. Each one of the at least one sealing end has a power electrode mounted thereon. 
     The at least one flexible LED strip is mounted in the transparent bending tube and each one of the at least one flexible LED strip has a flexible PCB and a plurality of LEDs. The flexible PCB is electrically connected with the at least one power electrode. The plurality of LEDs is separately mounted on the flexible PCB. 
     The flexible LED strip has the LEDs mounted thereon passes through the transparent bending tube with various shapes to form the bending LED tube. As the LEDs are separately mounted on the transparent bending tube, the LEDs can be uniformly allocated in the transparent bending tube. Moreover, because the LEDs are adjacent to the wall of the transparent bending tube  10 , not only can luminance of the bending LED bulb be enhanced, but also waste heat generated by the LEDs  22  can be dissipated out through the wall of the transparent bending tube  10 , so as to avoid high temperature resulting from accumulation of the waste heat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a first embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 2  is an enlarged side view in partial section of the bending LED bulb in  FIG. 1 ; 
         FIG. 3  is a front view of a second embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 4  is a front view of a third embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 5  is a front view of a fourth embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 6  is a front view of a fifth embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 7  is a perspective view of a sixth embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 8  is a front view of a seventh embodiment of a bending LED bulb in accordance with the present invention; 
         FIG. 9  is a front view showing a detailed structure of a flexible LED strip in accordance with the present invention; 
         FIG. 10  is a circuit diagram of  FIG. 9 ; 
         FIG. 11  is a side view in partial section of a first embodiment of the flexible LED strip in accordance with the present invention; 
         FIG. 12  is a side view in partial section of a second embodiment of the flexible LED strip in accordance with the present invention; 
         FIG. 13  is a front view in partial section of a conventional ball-type LED bulb; and 
         FIG. 14  is a top view of the conventional ball-type LED bulb in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 1 , a first embodiment of a bending LED bulb has a transparent bending tube  10  and at least one flexible LED strip  20 . 
     The transparent bending tube  10  has two sealing ends  11  and two power electrodes  12 ,  13 . The two sealing ends  11  are respectively formed on two ends of the transparent bending tube  10 . The two power electrodes  12 ,  13  are respectively mounted on the two sealing ends  11 . In the present embodiment, the transparent bending tube  10  is alternatively and repeatedly bent up and down to have the two sealing ends facing a same direction. 
     The at least one flexible LED strip  20  is received in the transparent bending tube  10 , and has a flexible printed circuit board (PCB)  21  and a plurality of LEDs  22 . The LEDs  22  are separately mounted on the flexible PCB  21 . Both ends of the flexible PCB  21  are electrically and respectively connected with the two power electrodes  12 ,  13  on the two ends of the transparent bending tube  10 . In an embodiment, the LEDs  22  are spaced on the flexible PCB  21  at equal intervals. Alternatively, the LEDs  22  may be spaced on the flexible PCB  21  at different intervals. 
     With reference to  FIG. 2 , as illustrated, the LEDs  22  are dispersed inside the transparent bending tube  10 , and each LED  22  is quite close to a wall of the transparent bending tube  10  and keeps distances apart from the adjacent LEDs  22 . Accordingly, the luminance of the bending LED bulb can be raised, and the heat generated by the LEDs  22  can be efficiently dissipated out to avoid accumulation of the heat. Therefore, high temperature arising from lengthy lighting duration can be effectively improved, and an additional heat sink is not necessary. 
     With reference to  FIG. 3 , in the second embodiment of the bending LED bulb, the transparent bending tube  10   a  is helically wounded to take a form of a circular helix. The flexible LED strip  20  is mounted in and extends throughout the transparent bending tube  10   a  and is bent according to a shape of the transparent bending tube  10   a  to disperse the plurality of LEDs  22  in the transparent bending tube  10   a.    
     With reference to  FIG. 4 , in the third embodiment of the bending LED bulb, the transparent bending tube  10   b  is U-shaped. The flexible LED strip  20  is mounted in and extends throughout the transparent bending tube  10   b  and is bent according to a shape of the transparent bending tube  10   b  to disperse the plurality of LEDs  22  in the transparent bending tube  10   b.    
     With reference to  FIG. 5 , in the fourth embodiment of the bending LED bulb, the transparent bending tube  10   c  is formed by a large C tube  101  and a small C tube  102  to take a form of a double C tube, in which the large C tube  101  is mounted around the small C tube  102  with openings of the two C tubes facing an identical direction. Two flexible LED strips  20  are respectively mounted in and extends throughout the large C tube  101  and the small C tube  102  and are bent according to shapes of the large C tube  101  and the small C tube  102  to disperse the plurality of LEDs  22  in the transparent bending tube  10   b . The two sealing ends  11  are integrally formed and are securely connected with the two ends of each of the large C tube  101  and the small C tube  102 . The two electrodes  12 ,  13  are mounted on the integrally formed sealing ends  11 . 
     With reference to  FIG. 6 , in the fifth embodiment of the bending LED bulb, the transparent bending tube  10   d  is spirally wounded. The flexible LED strip  20  is mounted in and extends throughout the transparent bending tube  10   d  and is bent according to a shape of the transparent bending tube  10   d  to disperse the plurality of LEDs  22  in the transparent bending tube  10   d.    
     With reference to  FIG. 7 , in the sixth embodiment of the bending LED bulb, the transparent bending tube  10   e  is helically wounded to take a form of a conic helix. One flexible LED strip  20  is mounted in and extends throughout the transparent bending tube  10   e  and is bent according to a shape of the transparent bending tube  10   e  to disperse the plurality of LEDs  22  in the transparent bending tube  10   e.    
     As illustrated by the foregoing embodiments, the transparent bending tube  10 ˜ 10   e  has at least one sealing end  11 . As shown in  FIGS. 1 ,  3 ,  4 ,  6 , two sealing ends  11  are mounted on the two ends of the transparent bending tube  10 ,  10   a ,  10   b ,  10   d . As shown in  FIGS. 5 ,  7 ,  8 , the transparent bending tube  10   c ,  110   e ,  10   f  has only one sealing end  11  having the power electrodes  12 ,  13  mounted therein. Other forms of the transparent bending tube are possible and fall within the scope of the present invention. 
     With reference to  FIG. 9 , the flexible LED strip  21  has two metal wires  211 ,  212  formed thereon. The two metal wires  211 ,  212  are electrically and respectively connected with the power electrodes  12 ,  13  of the transparent bending tube  10 . The LEDs  22  are soldered respectively on the two metal wires  211 ,  212 . When the power electrodes  12 ,  13  are electrically connected with a power source, the LEDs  22  can be lit. To enhance lighting efficiency, the plurality of LEDs  22  of the flexible LED strip  20  can be classified into several sub light groups  201 , for example, five LEDs  22  serially connected as a sub light group  201 . Multiple sub light groups  201  are parallelly connected and then are connected respectively with the two metal wires  211 ,  212  to form a equivalent circuit diagram as shown in  FIG. 10 . As mentioned earlier in an embodiment, the LEDs  22  are equally spaced on the flexible LED strip  20 . The distance between LEDs is preferably adjusted by a consumed wattage of an LED  22 . Specifically, the distance is proportional to the consumed wattage. It is comprehensible that the LEDs  22  spaced by different distance therebetween also fall within the scope of the present invention. 
     Besides, a total voltage consumed by the flexible LED strip  20  or all LEDs  22  of each sub light group  201  is equal to an input voltage of an external power source. For example, in an embodiment, if a driving voltage V f  required by an individual LED is 3.3 V and an external input voltage is 120 V, a total voltage of all the LEDs  22  serially connected in each sub light group  201  is a multiple of 3.3 V and the total voltage shall be substantially equal to the external input voltage. A plurality of sub light groups  201  can be further parallelly connected to the external input voltage or power. 
     To further enhance a cooling efficiency of the transparent bending tube  10 ˜ 10   f , the transparent bending tube  10 ˜ 10   f  can be vacuumed and then filled in with a gas having a heat transfer coefficient higher than that of air or inert gas to prevent high temperature from oxidizing metal wires  211 ,  212  or metal contacts. The vacuuming and the filling of the gas or inert gas with higher heat transfer coefficient can be carried out through the sealing end  11  of the transparent bending tube  10 ˜ 10   f  and with a duct of an external gas vacuum and a filling device. The sealing end  11  of the transparent bending tube  10 ˜ 10   f  can be formed by directly melting at least one opening of the transparent bending tube  10 ˜ 10   f , thereby saving additional material. The sealing end  11  that receives the power electrodes  12 ,  13  therein further has a non-conductive portion, such as a rubber plug or a ceramic plug, to seal at least one end of the transparent bending tube  10 ˜ 10   f  by tight fitting, press fitting or adhesive bonding. Moreover, the transparent bending tube  10 ˜ 10   f  of the present invention is preferably made of a glass material. Any other material or compound material (for example, silicon and the like) similar to glass also falls within the scope of the present invention. 
     With further reference to  FIG. 2 , to further enhance the cooling efficiency of the transparent bending tube  10 ˜ 10   f , a liquid  14  represented by the dash lines can be filled in the transparent bending tube  10  after the transparent bending tube  10 ˜ 10   f  is vacuumed. The vacuuming and the filling of the liquid  14  can be carried out through the sealing end  11  of the transparent bending tube  10 ˜ 10   f  and with a duct of an external gas vacuum and a filling device. 
     With reference to  FIG. 11 , to raise lumen value of the bending LED bulb, the LEDs  22  are mounted respectively on two opposite sides of the flexible PCB  21  of the flexible LED strip  20 . The resulting lumen value and uniformity of exit light can be effectively improved. With reference to  FIG. 12 , each transparent bending tube  10  has three flexible LED strips  20  mounted therein in a form of a triangular column so that the LEDs  22  can be positioned closely to the tube wall of the transparent bending tube  10  and the light exiting directions of the LEDs  22  are respectively separated one another by 120° apart. Therefore, the overall lumen value and the uniformity of exit light can be provided accordingly. 
     As known from the foregoing description, the flexible LED strip  20  having the LEDs  22  mounted thereon is mounted in and extends throughout the transparent bending tube  10  with various shapes to form the bending LED tube of the present invention. If the LEDs  22  are sequentially mounted on the transparent bending tube  10  at an equal interval, the LEDs  22  can be uniformly allocated in the transparent bending tube  10 . Moreover, because the LEDs  22  are adjacent to the wall of the transparent bending tube  10 , lumen value can be raised and the heats generated by the LEDs  22  can be dissipated out through the wall of the transparent bending tube  10  to avoid high temperature resulting from accumulation of the heat. 
     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.