Patent Publication Number: US-7712928-B2

Title: Street illuminating device

Description:
BACKGROUND 
   1. Technical Field 
   The present invention relates to illuminating devices, and particularly, to a street illuminating device with a number of solid state light emitting elements. 
   2. Description of Related Art 
   Solid state light emitting elements, such as light emitting diodes (LEDs) have been widely used in street illuminating devices. 
   An LED is capable of producing a visible light in a certain wavelength. However, 80% to 90% energy of the LED is converted to heat, which needs to be dissipated, and only the small remainder is converted to the light. 
   The light from an LED needs to be gathered if a higher light concentration and brightness are needed. However, if a number of LEDs are used, it becomes complicated to efficiently gather light for each LED. 
   What is needed, therefore, is a street illuminating device with a number of solid state light emitting elements, which is compact, and in which light gather and heat dissipation are simply accomplished. 
   SUMMARY 
   A street illuminating device includes a retaining frame, a light source module, and a heat dissipating module. The light source module includes a printed circuit board retained in the retaining frame, a number of solid state lighting elements, and a light reflecting plate. The printed circuit board has a first surface and an opposite second surface. The solid state lighting elements are arranged on the first surface of the printed circuit board. The light reflecting plate includes a number of through holes with inner reflecting surfaces. The light reflecting plate is disposed on the first surface of the printed circuit board with the solid state lighting elements received in the respective through holes. The heat dissipating module is in thermal contact with the second surface of the printed circuit board. 
   Other advantages and novel features of the present street illuminating device will become more apparent from the following detailed description of embodiment when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the street illuminating device 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 street illuminating device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is a schematic view of a street illuminating device in accordance with an embodiment of present invention. 
       FIG. 2  is an exposed view of the street illuminating device shown in  FIG. 1 . 
       FIG. 3  is a cross-sectional view of the street illuminating device shown in  FIG. 1  taken along a III-III line. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Embodiment of the present street illuminating device will now be described in detail below and with reference to the drawings. 
   Referring to  FIGS. 1 and 2 , a street illuminating device  100  is provided. The street illuminating device  100  includes a retaining frame  11 , a light source module  12 , and a heat dissipating module  13 . 
   Also referring to  FIG. 3 , the retaining frame  11  has a first retaining step  111  and a second retaining step  112  formed in an inner wall thereof. The second retaining step  112  is adjacent to the first retaining step  111 . The retaining frame  11  can be made from aluminum material. 
   The light source module  12  includes a printed circuit board  121 , a number of solid state lighting elements  122 , and a light reflecting plate  123 . The printed circuit board  121  is retained on the first step  111  of the retaining frame  11 . The printed circuit board  121  has a first surface  121   a  and an opposite second surface  121   b . Each of the solid state lighting elements  122  is an LED. The solid state lighting elements  122  are arranged the first surface  121   a  of the printed circuit board  121 , and are evenly spaced apart from each other. The light reflecting plate  123  is engaged with an inner wall of the retaining frame  11 . The light reflecting plate  123  includes a number of through holes  124  with inner reflecting surfaces  124   a . The through holes  124  each are truncated cone shaped, and have a smaller opening  123   a  and a larger opening  123   b . The light reflecting plate  123  is attached on the first surface  121   a  of the printed circuit board  121 , with each of the solid state lighting elements  122  received in the respective one of the through holes  124 . The smaller opening  123   a  of each of the through holes  124  is adjacent to the respective one of the solid state lighting elements  122 , and the larger opening  123   b  of each of the through holes  124  is apart from the respective one of the solid state lighting elements  122 . 
   The heat dissipating module  13  includes a heat conduction plate  133 , a number of ring-shaped heat pipes  132  with working fluid (not shown) therein, and a number of heat sinks  131 . The heat conduction plate  133  is retained on the second retaining step  112  of the retaining frame  11 . The heat conduction plate  133  can be made from the same material as the retaining frame  11 , or from some other material with heat transfer capability higher than that of the material of the retaining frame  11 . The heat conduction plate  133  is in thermal contact with the second surface  121   b  of the printed circuit board  121 . Each of the ring-shaped heat pipes  132  has an evaporator section  132   a , and a condenser section  132   b . The evaporator sections  132   a  of the heat pipes  132  are in thermal contact with the heat conduction plate  133 . The condenser sections  132   b  of the heat pipes  132  penetrate through the heat sinks  131 , such that the heat sinks  131  are in thermal contact with the heat pipes  132 . 
   Due to the compact nature of the retaining frame  11 , the entire street illuminating device  20  is compact. Due to the reflectivity of the respective inner reflecting surfaces  124   a  of the light reflecting plate  123 , light emitted by the respective solid state lighting elements  122  can be gathered and output only from the respective through holes  124 , thus reducing light loss, increasing brightness, and providing a higher light concentration. Heat generated by the solid state lighting elements  122  can be conducted out by the heat conduction plate  133  and also by the retaining frame  11 . Configuration and cooperation of the ring-shaped heat pipes  132  with the heat sinks  131  help provide a compact efficient module. 
   It is understood that the above-described embodiments are intended to illustrate rather than limit the invention. Variations may be made to the embodiments and methods without departing from the spirit of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.