Abstract:
An LED (light emitting diode) lighting apparatus includes an LED, a light adjusting device and a shell. The LED includes a main lighting surface and a heat dissipating surface. The shell receives the LED and the light adjusting device therein, the shell having a light emitting window for light emitted from the LED to transmit therethrough after the light is directed by the light adjusting device. The heat dissipating surface of the LED connects the light emitting window, and heat generated by the LED is transferred from the heat dissipating surface to the light emitting window to prevent snow from accumulating on the light emitting window.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to lighting apparatuses, and more particularly, to an LED lighting apparatus suitable for use as a traffic or advertisement lighting device in a region which may have snowfall in snow season. 
     2. Description of Related Art 
     LEDs (Light-Emitting Diodes) have many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, easy driving, long term reliability, and environmental friendliness. Such advantages have promoted the wide use of the LEDs as a light source. Nowadays, LED lighting apparatuses are commonly applied as traffic lights or indicators or advertisement billboard. However, in the region where there is snowfall in snow season, the snow can cover the light output surface of the LED lighting apparatuses, whereby the lighting effect or indicating effect of the LED lighting apparatuses is seriously affected. Blocked lighting or indicating effect of the traffic lights or indicators will cause traffic disturbance or even traffic accidents. Blocked lighting of advertisement billboard cause the advertisement billboard to lose its intended purpose. 
     What is needed, therefore, is an LED lighting apparatus which can overcome the limitations described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present disclosure 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 disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a cross section of an LED lighting apparatus in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is schematic, cross section of an LED used in the LED lighting apparatus of  FIG. 1 . 
         FIG. 3  is a front view of the LED lighting apparatus of  FIG. 1 . 
         FIG. 4  is a cross section of an LED lighting apparatus in accordance with a second embodiment of the present disclosure. 
         FIG. 5  is a front view of the LED lighting apparatus of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIGS. 1-2 , an LED (light emitting diode) lighting apparatus  60  in accordance with a first embodiment of the present disclosure is shown. The LED lighting apparatus  60  can be used in a traffic light or a traffic indicator. The LED lighting apparatus  60  includes a shell  40 , a plurality of LEDs  10  arranging in the shell  40  and a light adjusting device received in the shell  40 . 
     Each LED  10  includes a substrate  20  and an LED chip  30  securely located on a rear surface of the substrate  20 . The substrate  20  acts as electrical connecting portion, mechanical supporting portion and heat dissipating portion of the LED  10 . The substrate  20  preferably is made of a metal core printed circuit board (MCPCB) which can effectively absorb heat generated by the LED chip  30 . A heat dissipating surface  21  is defined at a front surface the substrate  20  of the LED  10  opposite to the LED chip  30 . The rear surface of the LED  10  is defined as a main lighting surface  31 . The main lighting surface  31  faces the light adjusting device. Light emitted from the main lighting surface  31  is adjusted by the adjusting device. In the following description, direction from the main lighting surface  31  to the light adjusting device is defined as direction “a” shown with an arrow and an opposite direction defined as direction “b” shown with an opposite arrow. 
     In this embodiment, the LED lighting apparatus  60  works as a traffic light or a traffic indicator and the adjusting device is a reflecting device  50  including a concave, curved reflecting surface  51 . 
     The shell  40  is circular column-shaped laid horizontally and a size thereof is similar to a typical traffic light or indicator unit. The shell  40  includes a light emitting window  41  and a housing  42 . It is preferred that the housing  40  is made of durable material with good thermal conductivity such as metal. The reflecting device  50  is set inside a rear portion of the housing  42 , round and concave, and has a forward projected area slight smaller than an area of the window  41 , whereby light reflected by the reflecting device  50  can be substantially directed to an entirety of the window  41 . Also referring to  FIG. 3 , the light emitting window  41  includes a bracket  43  in a form of a square cross and several (four) transmission portions  44  each in a corresponding quadrant defined by the square cross. The bracket  43  is square cross-shaped and the LEDs  10  are set on a rear surface of bracket  43  and located corresponding to arms and a center of the bracket  43 . The substrates  20  of the LEDs  10  are connected with the rear surface of the bracket  43 . The heat dissipating surfaces  21  of the LEDs  10  connect the bracket  43  directly. It is preferred that the bracket  43  is also made of durable material with good thermal conductivity such as metal. The transmission portions  44  are made of light pervious material such as transparent or translucent plastic or glass so that light emitted from the LEDs  10  and reflected from the reflecting device  50  can emit outside the LED lighting apparatus  60  through the transmission portions  44 . The transmission portions  44  totally form a whole lighting surface  410  of the LED light apparatus  60 . The direction “a” directs from the bracket  43  to the reflecting device  50  and the direction “b” directs from the reflecting device  50  to the transmission portions  44 . The heat dissipating surfaces  21  of the LEDs  10  face the whole lighting surface  410 . The main lighting surfaces  31  of the LEDs  10  face the reflecting surface  51 . 
     When the LED lighting apparatus  60  is working, one or more LEDs  10  emit light. Light emitted from the LEDs  10  transmits towards the reflecting surface  51  along the direction “a”, then is reflected by the reflecting surface  51  and continue to transmit substantially along the direction “b” to travel through the whole lighting surface  410  and reach outside of the LED lighting apparatus  60 . At the same time, heat generated by the LEDs  10  is transferred to the bracket  43  and further transferred to the whole lighting surface  410 . As a result, a temperature of the whole lighting surface  410  is higher than that of outside environment. Thus, snow covered the lighting surface  410  can be melt by the heat generated by the LEDs  10  and the LED lighting apparatus  60  keeps good lighting effect even when there is snowfall when the LED light apparatus  60  is used. 
     Referring to  FIGS. 4-5 , an LED (light emitting diode) lighting apparatus  60   a  in accordance with a second embodiment of the present disclosure is shown. Similar to the LED lighting apparatus  60  of the first embodiment, the LED lighting apparatus  60   a  includes a shell  40 , a plurality of LEDs  10  arranging in the shell  40  and a light adjusting device received in the shell  40 . The shell  40  includes a light emitting window  41  from which the light travels through the LED lighting apparatus  60   a  to the outside and a housing  42  in which the light adjusting device is received. A direction from the LEDs  10  to the light adjusting device is defined as direction “a” and an opposite direction is defined as direction “b”. 
     Differing from the LED lighting apparatus  60  of the first embodiment, the LED lighting apparatus  60   a  of this embodiment works as an advertising lamp and LEDs  10  are arranged in a manner according to advertising design. It is preferred that the LEDs  10  are set at a border portion of the light emitting window  41  and electrically connected together by circuit extending inside the light emitting window  41  and around the border portion of the light emitting window  41 . The adjusting device is a reflecting device  50   a  including a flat reflecting surface  51   a . Light emitted from the LEDs  10  travels towards the reflecting surface  51   a  along the direction “a”, and then is reflected by the reflecting surface  51   a  along the direction “b” to emit outside of the LED lighting apparatus  60   a  via the light emitting window  41 . Heat generated from the LEDs  10  is transferred to the light emitting window  41  directly thereby to melt snow which may accumulate on the light emitting window  41 . 
     Since heat generated by the LEDs  10 ,  10   a  can be transferred to the light emitting window  41 , the light emitting window  41  keeps a temperature thereof higher than outside environment. Even though snow falls on the LED lighting apparatus  60 ,  60   a , the higher temperature of the light emitting window  41  will melt the snow. Thus, the LED lighting apparatus  60 ,  60   a  can keep good lighting effect no matter in a warm season or a snow season. 
     It is believed that the present disclosure and its 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 present disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments.