Patent Publication Number: US-8534872-B2

Title: LED illumination device

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure generally relates to light emitting diode (LED) illumination devices, and particularly to an LED illumination device with an illumination direction thereof being adjustable. 
     2. Description of Related Art 
     LEDs (light emitting diodes) are preferred for use in LED illumination devices rather than CCFLs (cold cathode fluorescent lamps) due to a high brightness, a long lifespan, and less pollution of the LED. 
     Nowadays, screw-type LED illumination devices are widely used. The screw-type LED illumination device is provided with a screw-type lamp cap at one end thereof for electrically connecting the LED illumination device with an external power source. Generally, the screw-type LED illumination devices emit light outwardly around a whole outer circumferential surface thereof. In use, the screw-type lamp cap of the LED illumination device is screwed into a screw-type lamp holder which is electrically connected with the external power source, until the screw-type lamp cap is firmly fixed in and electrically connected with the screw-type lamp holder to ensure a good electrical connection between the screw-type lamp cap and the screw-type lamp holder. 
     However, some screw-type LED illumination devices are designed to emit light only through a portion of an outer circumferential surface of the LED illumination device. Therefore, the screw-type LED illumination device is often required to be turned from a first position to a second position so that the emitted light can illuminate on the desired objects at the second position. However, after the screw-type LED illumination device is turned from the first position to the second position, the screw-type lamp cap may be electrically disengaged from the screw-type lamp holder to cause an electrical connection between the screw-type LED illumination device and the screw-type lamp holder to be cut off. 
     Therefore, it is desirable to provide an LED illumination device with an illumination direction thereof being adjustable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric, assembled view of an LED illumination device in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is a cross sectional view of the LED illumination device of  FIG. 1 . 
         FIG. 3  is a cross sectional view of an LED illumination device in accordance with an alternative embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an LED illumination device  100  according to a first embodiment of the present disclosure includes a heat dissipation part  10 , an optical part  20 , and an electric part  30 . 
     The heat dissipation part  10  includes a heat dissipation member  11 . The heat dissipation member  11  is made of a thermal conductive material such as aluminum. The heat dissipation member  11  includes a vertical base plate  111  and a plurality of fins  112  extending horizontally outwardly from a left side of the base plate  111 . The base plate  111  is rectangular. The fins  112  are semicircular and spaced from each other along a lengthwise direction of the base plate  111 . A diameter of the fin  112  is equal to a width of the base plate  111 . A right side of the base plate  111  forms a heat absorbing surface  113 . 
     The optical part  20  is arranged at a right side of the heat dissipation part  10 . The optical part  20  includes an LED module  21  and an envelope  22  covering the LED module  21 . The LED module  21  includes a substrate  211 , a plurality of LEDs  212  arranged on the substrate  211 , and a plurality of electrodes  213  formed on the substrate  211 . The LEDs  212  are evenly spaced from each other and electrically attached on the substrate  211  with emitting surfaces thereof facing the envelope  22 . The substrate  211  of the LED module  21  is rectangular and attached on the heat absorbing surface  113  of the heat dissipation member  11 , whereby heat generated by the LEDs  212  is conducted to the heat dissipation member  11  via the substrate  211  for dissipation. A layer of thermal interface material (TIM) may be applied between the substrate  211  of the LED module  21  and the heat absorbing surface  113  of the heat dissipation member  11  to eliminate an air interstice therebetween, to thereby enhance a heat conduction efficiency between the LED module  21  and the heat dissipation member  11 . The substrate  211  defines a plurality of mounting holes  2111  near front and rear edges thereof. Fasters such as screws are adopted to extend through the mounting holes  2111  and screw into the base plate  111  to mount the substrate  211  of the LED module  21  onto the heat absorbing surface  113  of the heat dissipation member  11 . Alternatively, the substrate  211  of the LED module  21  can be attached to the heat absorbing surface  113  of the heat dissipation member  11  fixedly and intimately through surface mount technology (SMT), whereby an interface between the substrate  211  and the base plate  111  can be eliminated and a thermal resistance between the LED module  21  and the heat dissipation member  11  is reduced. 
     The envelope  22  is transparent and has a semicircular cross section. A diameter of the cross section of the envelope  22  is equal to that of the fin  112 . The envelope  22  is arranged at the right side of the base plate  111  of the heat dissipation member  11  and mounted on the base plate  111 , with the LED module  21  covered by the envelope  22 . The envelope  22  and the fins  112  of the heat dissipation member  11  cooperatively define an elongated, cylindrical profile of the LED illumination device  100 . The envelope  22  functions as an optical lens for the LED module  21  to guide light emitted by the LEDs  212  of the LED module  21  to an ambient environment and as a shell to protect the LED module  21  from dust and external damage. 
     The electric part  30  is arranged at a bottom end of the LED illumination device  100 . The electric part  30  is connected with the heat dissipation part  10  and the optical part  20 . The electric part  30  includes a circuit board  31 , a casing  32  and a lamp cap  33 . The circuit board  31  is received in the casing  32 . The circuit board  31  has a pair of first wires  301  extending upwardly and a pair of second wires  302  extending downwardly therefrom. The first wires  301  are connected with the electrodes  213  of the LED module  21 , and the second wires  302  are connected with the lamp cap  33  which is used to connect with an external power source to provide the LED module  21  a necessary power to emit light. 
     The casing  32  is cup-shaped. The casing  32  includes a large section  321  and a small section  322  at two opposite ends thereof. The large section  321  is mounted to bottom ends of the heat dissipation part  10  and the optical part  20 , and the small section  322  is located away from the heat dissipation part  10  and the optical part  20 . The large section  321  connects with the heat dissipation member  11  of the heat dissipation part  10  and the envelope  22  of the optical part  20 . The circuit board  31  is received in the large section  321 . The large section  321  extends a plurality of mounting seats  3211  upwardly from an inner surface thereof. A plurality of mounting poles  311  extends downwardly from the circuit board  31  corresponding to the mounting seats  3211 . Each of the mounting poles  311  faces a corresponding mounting seat  3211  of the large section  321  for mounting the circuit board  31  in the large section  321 . The large section  321  defines a plurality of pores  3212  through a circumferential surface at a top end thereof. The pore  3212  communicates an inner space of the casing  32  with the ambient environment outside the casing  32 , whereby heat generated by the circuit board  31  can be dissipated to the ambient environment through the pores  3212 . The small section  322  of the casing  32  defines a plurality of threads  3221  in an outer surface thereof to screw with the lamp cap  33 . 
     The lamp cap  33  includes a sleeve electrode  34  and a spring electrode  35 . The sleeve electrode  34  is made of an electrically conductive metal sheet. The sleeve electrode  34  includes a tubular-shaped main body  341  and a cone-shaped bottom plate  342  extending downwardly from a bottom end of the main body  341 . The main body  341  defines a plurality of threads in inner and outer surfaces thereof. The threads of the inner and the outer surfaces of the main body  341  are complementary. The threads of the inner surface of the main body  341  match with the threads  3221  of the small section  322  of the casing  32 . The bottom plate  342  defines a through hole  3421  in a central portion thereof for receiving an electric pole  343 . A diameter of the electric pole  343  is smaller than that of the through hole  3421  of the bottom plate  342 . An insulating member  344  is attached on an inner surface of the bottom plate  342 . The electric pole  343  extends through the insulating member  344  and is electrically insulated from the bottom plate  342  via the insulating member  344 . The pair of second wires  302  are respectively connected with the inner surface of the main body  341  and the electric pole  343 . 
     The spring electrode  35  is located outside the sleeve electrode  34  and attached to an outer surface of the bottom plate  342  of the sleeve electrode  34 . The spring electrode  35  includes a spring  351 , an insulating seat  352 , and an electrical conductive plate  353 . An outer diameter of the insulating seat  352  is smaller than that of the main body  341  of the sleeve electrode  34 . The insulating seat  352  defines an aperture  3521  through a central portion thereof. The electrical conductive plate  353  is mounted at a bottom end of the insulating seat  352  and faces the aperture  3521 . The spring  351  is received in the aperture  3521  of the insulating seat  352  with two opposite ends thereof respectively connected with the electric pole  343  and the electrical conductive plate  353 . A diameter of the spring  351  is smaller than that of the aperture  3521  of the insulating seat  352 . Before the spring  351  is compressed, a lower portion of the spring  351  is received in the aperture  3521  of the insulating seat  352 , and an upper portion of the spring  351  protrudes out of the insulating seat  352 , whereby the bottom plate  342  of the sleeve electrode  34  is spaced from the insulating seat  352 , as shown in  FIG. 1 . A top end of the insulating seat  352  faces the bottom plate  342  of the sleeve electrode  34 . A bottom end of the insulating seat  352  is tapered downwardly, and a tapered outer surface  3522  is formed at the bottom end of the insulating seat  352 . Thus, when the lamp cap  33  is screwed into the lamp holder  400 , the insulating seat  352  can be easily inserted into the lamp holder  400  due to the presence of the tapered outer surface  3522  of the insulating seat  352 . The electric pole  343 , the spring  351  and the electrical conductive plate  353  each are made of an electrically conductive material having a low electrical resistance. 
     The lamp holder  400  is a conventional one and defines a cavity  41  therein for receiving the lamp cap  33  of the LED illumination device  100 . The cavity  41  is substantially cylindrical. The lamp holder  400  includes a screw cap  42  attached on an inner surface of the cavity  41  and a resilient flake  43  mounted at a central portion of a bottom end of the cavity  41 . The screw cap  42  and the resilient flake  43  are respectively connected with a naught wire  401  and a live wire  402  of the external power source via two connectors  44 . 
     Referring to  FIG. 2 , in assembling the LED illumination device  100  onto the lamp holder  400 , the lamp cap  33  of the LED illumination device  100  is screwed into the cavity  41  of the lamp holder  400 . As the lamp cap  33  is screwed into the lamp holder  400 , the spring  351  of the spring electrode  35  is gradually depressed by the sleeve electrode  34  towards the resilient flake  43 , whereby the electrical conductive plate  353  of the spring electrode  35  is pushed to resiliently and intimately contact with the resilient flake  43  of the lamp holder  400 . Since the spring  351  can be freely compressed, the lamp cap  33  can be turned within 360 degrees to adjust the illumination direction of the LED illumination device without a worry that the electrical conductive plate  353  of the lamp cap  33  will be electrically disengaged from the resilient flake  43  of the lamp holder  400 . In use, the optical part  20  of the LED illumination device  100  can be easily adjusted to the proper position so that the emitted light of the LED illumination device  100  can illuminate on desired objects while the lamp cap  33  of the LED illumination device  100  is still maintained in a good electrical connection with the lamp holder  400 . 
     Referring to  FIG. 3 , an LED illumination device  100   a  according to an alternative embodiment is illustrated. Except the following differences, the LED illumination device  100   a  of the present embodiment is essentially the same as the LED illumination device  100  shown in  FIGS. 1 and 2 . In the present embodiment, the lamp cap  33   a  further includes a tray  36  attached to an outer surface of the bottom plate  342  of the sleeve electrode  34 . The tray  36  protrudes a plurality of positioning pins  361  downwardly therefrom, and the insulating seat  352  of the spring electrode  35  defines a plurality of blind holes  3523  corresponding to the positioning pins  361 . When the lamp cap  33   a  of the LED illumination device  100   a  is screwed into the lamp holder  400 , each of the positioning pins  361  slides into a corresponding blind hole  3523  to ensure the spring electrode  35  to move along an axial direction of the cavity  41  of lamp holder  400 . In addition, the positioning pins  361  and the blind holes  3523  enable a stable electrical connection between the electrical conductive plate  353  of the spring electrode  35  and the resilient flake  43  of the lamp holder  400  when the LED illumination device  100   a  is turned to adjust the illumination direction thereof. 
     It is to be understood, however, that 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 embodiments, the disclosure is illustrative only, and 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.