Abstract:
An exemplary light fixture includes a holder, an envelope and a lamp body. The lamp body includes a heat dissipation portion, a light source and a shield. The heat dissipation portion has top and bottom ends connecting to the holder and the envelope, respectively. The light source is mounted on the bottom end of the heat dissipation portion and covered by the envelope. The heat dissipation portion includes a plurality of fins extending from the top end to the bottom end of the heat dissipation portion. A passage is defined between every two adjacent fins. The shield surrounds the fins and defines a plurality of windows therein, communicating with the passages.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to light fixtures, and more particularly to a light fixture for use with solid state light emitters, e.g., light emitting diodes (LEDs). 
     2. Description of Related Art 
     LEDs as a source of illumination provide advantages such as resistance to shock and nearly limitless lifetime under specific conditions. Thus, light fixtures utilizing LEDs present a cost-effective yet high quality replacement for incandescent and fluorescent lamps. 
     A lot of heat is generated during the work of an LED light fixture, which, if not adequately addressed, impacts the reliability of the LED light fixture. A typical way of providing an LED light fixture with good heat dissipation capability is increasing the numbers of fins in the LED light fixture. However, the increase of the fins requires the fins to be extremely thin. The extremely thin fins are easy to deform or even break, which not only impairs the heat dissipation capability of the light fixture, but also destroys the aesthetics of the light fixture. In addition, the extremely thin fins are so sharp that they are dangerous to the users during the installation or replacement of the LED light fixture. 
     What is needed therefore is an LED light fixture which can overcome the above limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views. 
         FIG. 1  is an isometric, exploded assembled view of an LED light fixture in accordance with an embodiment of the present disclosure. 
         FIG. 2  is similar to  FIG. 1 , but viewed from a different aspect. 
         FIG. 3  is an enlarged view of a shield of the LED light fixture in  FIG. 1 . 
         FIG. 4  is an isometric, assembled view of the LED light fixture in  FIG. 1 . 
         FIG. 5  is a cross sectional view of the LED light fixture, taken along line V-V of  FIG. 4 . 
         FIG. 6  is an isometric, assembled view of an LED light fixture in accordance with another embodiment of the present disclosure. 
         FIG. 7  is a cross sectional view of the LED light fixture, taken along line VII-VII of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 ,  2  and  4 , an LED light fixture in accordance with an embodiment of the present disclosure comprises a holder  100  for connecting with a power source (not shown), an envelope  300 , and a lamp body  200  with a top end connecting with the holder  100  and a bottom end connecting with the envelope  300 . 
     The holder  100  comprises a conducting portion  10  and a connecting portion  11  extending downwardly from the conducting portion  10 . The conducting portion  10  has a columned shape. Threads  101  are formed on an outer surface of the conducting portion  10 . A conducting pad  102  is formed on a top end of the conducting portion  10 . The conducting portion  10  is configured for connecting the power source to provide a power for the LED light fixture. The connecting portion  11  comprises a connecting bar  110  and a connecting bowl  111  extending downwardly from the connecting bar  110 . The connecting bar  110  inserts into the conducting portion  10  and engages with the conducting portion  10 . The connecting bowl  111  has a substantially spherical contour. Two positioning holes  112  are defined in the connecting bowl  111  for screws  12  extending therethrough to connect the holder  100  and the lamp body  200  together. The connecting portion  11  is made of electrically insulate material such as ceramics. 
     The lamp body  200  comprises a heat dissipation portion  20 , an LED module  21  attached to a bottom of the heat dissipation portion  20  and a shield  22  surrounding the heat dissipation portion  20 . 
     The heat dissipation portion  20  is made of material with good heat conductivity such as aluminum, copper or an alloy thereof. The heat dissipation portion  20  comprises a bottom plate  201 , a top plate  203 , and a fin unit  202  sandwiched between the bottom and top plates  201 ,  203 . 
     The bottom plate  201  is round and attached to a bottom end of the fin unit  202 . A connecting hole  208  is defined in a center of the bottom plate  201 . Two securing holes  209  are defined in the bottom plate  201  and positioned at two sides of the connecting hole  208 . The connecting hole  28  is configured for wires (shown in  FIG. 5 ) extending therethrough to electrically connect a power module  23  and the LED module  21 . The power module  23  is assembled in the lamp body  200  and the holder  100  to provide control signals and required power for the LED module  21 . The securing holes  209  are used to engagingly receive the screws  12  which connect the LED module  21  and the heat dissipation portion  20  together. 
     The top plate  203  has an annular shape. The top plate  203  is attached to a top end of the fin unit  202 . The top plate  203  can be connected to the connecting bowl  111  by the screws  12  extending through the positioning holes  112  of the connecting bowl  111 . 
     Also referring to  FIG. 5 , the fin unit  202  comprises a tube  40  and a plurality of fins  204  surrounding the tube  40 . The fins  204  are attached to an outer surface of the tube  40  and extend radially and outwardly from the outer surface of the tube  40 . Each fin  204  comprises a main body  205  and a bending portion  206  extending from the main body  205 . The main body  205  is vertical to the top and bottom plates  203 ,  201 . The main body  205  has a substantially trapezoid shape. An outer edge of the main body  205  is arced. A passage is defined between two adjacent main bodies  205  for allowing air to flow therethrough. The bending portion  206  comprises a bottom bending plate  51  bending from a bottom edge of the main body  205 , a lateral bending plate  52  bending from an inner edge of the main body  205 , and a top bending plate  53  bending from a top edge of the main body  205 . The bottom, lateral and top bending plates  51 ,  52 ,  53  extend from a same side of the main body  205 . The bottom bending plate  51  is attached to the bottom plate  201  of the heat dissipation portion  20 . The top bending plate  53  is attached to the top plate  203  of the heat dissipation portion  20 . The lateral bending plate  52  is attached to the outer surface of the tube  40 . The fins  204  also extend from the top plate  203  to the bottom plate  201 . The power module  23  inserts in the tube  40  and electrically connects with the LED module  21  and the holder  100 . A top end of the tube  40  extends through the top plate  203 . 
     Also referring to  FIG. 3 , the shield  22  can be made of metal or plastic. The shield  22  comprises a first engaging portion  220 , a second engaging portion  221  and a protecting portion  222  interconnecting the first and second engaging portions  220 ,  221 . The first engaging portion  220  has an annular shape and engages with a periphery of the top plate  203 . The second engaging portion  221  also has an annular shape but is larger than the first engaging portion  220 . The second engaging portion  221  engages with a periphery of the bottom plate  201 . The second engaging portion  221  also engages with the envelope  300 . A plurality of grooves  223  is defined in an inner surface of the protecting portion  222 . The grooves  223  extend along an extending direction of the main bodies  205  of the fins  204  and are positioned corresponding to the outer edges of the main bodies  205  respectively. The grooves  223  each have a configuration similar to that of each of the outer edges of the main bodies  205 , whereby the grooves  223  fittingly receive the outer edges of the main bodies  205  of the fins  204  therein, respectively. A plurality of windows  224  is defined in the protecting portion  222 . The windows  224  extend along the extending direction of the main bodies  205  of the fins  204 . Each window  224  is communicated with a corresponding passage between two adjacent fins  204  and positioned between two adjacent grooves  223 . 
     The LED module  21  comprises a circuit board  210  and a plurality of LEDs  211  mounted on the circuit board  210 . The circuit board  210  is round. The circuit board  210  is secured on the bottom plate  201  of the heat dissipation portion  20  by screws  12 . 
     The envelope  300  is made of transparent or translucent material such as glass or resin. The envelope  300  comprises a semi-spherical light transmitting portion  30  and an abutting portion  31  extending from an opening of the light transmitting portion  30 . The abutting portion  31  is engagingly received in the second engaging portion  221  of the shield  22 . 
     Referring to  FIGS. 6 and 7 , an LED light fixture in accordance with another embodiment of the present disclosure is shown. The LED light fixture is similar to that in the previous embodiment. One of the differences therebetween is that the main bodies  205  of the fins  204  each have a trapezium shape and outer edges of the main bodies  205  are straight. 
     Further, another difference is that the windows  224  defined in the protecting portion  222  of the shield  22  extend along a direction perpendicular to the extending direction of the main bodies  205  of the fins  204 . The windows  224  are arranged in a matrix with several columns. The top window in each column of the windows  224  has the shortest length. The bottom window in each column of the windows  224  has the longest length. A spacing region  225  is positioned between two adjacent columns of the windows  224 . 
     The holder  100  is preferably a standard holder such that the LED light fixture can replace a traditional incandescent bulb. 
     The LED light fixture provided in the present disclosure has a shield  22  formed outside of the fins  204 . Thus, the fins  204  are not easy to deform or break and will not hurt the user&#39;s hand when he (she) grips the LED light fixture for installation or replacement. 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.