Abstract:
An exemplary reflective housing for a LED illuminator is provided. The reflective housing includes a plurality of side walls cooperatively forming a hollow shell. The hollow shell has a first opening and a second opening opposite to the first opening. The hollow shell tapers from the first opening to the second opening. Inner surfaces of the side walls are light reflective surfaces. The first opening has a polygonal shape having more than four sides. The first opening includes two parallel sides. Four endpoints of the first opening cooperatively form an imaginary quadrangle. Remaining sides are located at an exterior of the imaginary quadrangle. A line segment obtained by intersecting any straight lines parallel to the parallel sides is shorter than a distance between the two parallel sides. The second opening is configured for accommodating an LED light source therein.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosure relates generally to an illuminator, and particularly to a reflective housing and an illuminator having the reflective housing, and a light source. 
         [0003]    2. Description of Related Art 
         [0004]    In recent years, light emitting diodes (LEDs) have become highly efficient light sources and are used widely in such fields as automotive, displays, and street illuminators. 
         [0005]    Light generated by LEDs has the advantage in that it can be redirected or aimed by using some kind of reflectors. However, because a light field of the LED is usually concentrated, illuminating devices using LEDs cannot meet the needs of illuminating a relatively large area. Further, in some cases, such as the street lamp, a long and narrow light field is desired but not easily obtained with present methods. 
         [0006]    Therefore, there is a need in the art for a reflective housing and an LED illuminator, which overcomes the above-mentioned shortcomings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    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, all the views are schematic, and like reference numerals designate corresponding parts throughout the several views. 
           [0008]      FIG. 1  is an isometric view of an LED illuminator in accordance with a first embodiment. 
           [0009]      FIG. 2  is an exploded, isometric view of the LED illuminator of  FIG. 1 . 
           [0010]      FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 1 . 
           [0011]      FIG. 4  shows a light field of the LED illuminator of  FIG. 1 . 
           [0012]      FIG. 5  is a diagram showing a light-distributing curve for illumination of the LED illuminator of  FIG. 1 . 
           [0013]      FIG. 6  is a cross-sectional view of a reflective housing for an LED illuminator in accordance with a second exemplary embodiment. 
           [0014]      FIG. 7  is a cross-sectional view of a reflective housing for an LED illuminator in accordance with a third exemplary embodiment. 
           [0015]      FIG. 8  is a cross-sectional view of a light-pervious cover of an LED illuminator in accordance with a fourth exemplary embodiment. 
           [0016]      FIG. 9  is a cross-sectional view of a light-pervious cover of an LED illuminator in accordance with a fifth exemplary embodiment. 
           [0017]      FIG. 10  is a cross-sectional view of a light-pervious cover of an LED illuminator in accordance with a sixth exemplary embodiment. 
           [0018]      FIG. 11  is a top plan view of an LED illuminator in accordance with a seventh embodiment. 
           [0019]      FIG. 12  is a diagram showing a light-distributing curve for illumination of the LED illuminator of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring to  FIGS. 1 to 3 , an LED illuminator  100  of a first exemplary embodiment includes a reflective housing  120 , two light sources  140  and a light-pervious cover  160 . 
         [0021]    The reflective housing  120  has a hollow frustum shape of hexagonal-pyramid. The reflective housing  120  includes six side walls  122  and a bottom wall  124 . The bottom wall  124  is fixed to one distal end of each side wall  122 . A hexagonal opening  126  is defined opposite to the bottom wall  124 . The reflective housing  120  tapers from the hexagonal opening  126  to the bottom wall  124 . An inner surface of each of the side walls  122  is a reflective surface  128 . In this embodiment, the reflective surface  128  is a flat surface. An inner surface of the bottom wall  124  is a fixing surface  130  for fixing the two light sources  140  thereon. Light emitted from the light sources  140  are transmitted to exterior through the hexagonal opening  126 . 
         [0022]    The fixing surface  130  has a substantially same shape as the hexagonal opening  126 . Therefore, only the opening  126  is described in detail as follows. The hexagonal opening  126  is axially symmetric in respect to an axial line O 1  that passes through two endpoints of the hexagonal opening  126 . The hexagonal opening  126  has two sides  1262  and  1264  parallel with the axial line O 1 . The two parallel sides  1262  and  1264  are at two opposite sides of the axial line O 1  and have a distance D 1  therebetween. Straight lines parallel with the parallel sides  1262  and  1264  are intersected by the sides of the hexagonal opening  126  to form line segments. The longest one of the line segments has a distance D 2  between two endpoints of the opening  126  that the axial line O 1  passes through. The distance D 1  is larger than the distance D 2 . Four endpoints of the two sides  1262  and  1264  cooperatively form an imaginary quadrangle Q 1 . The remaining two endpoints of the hexagonal opening  126  passing through the axial line O 1  are located at an exterior of the imaginary quadrangle Q 1 , thereby forming two structures projected from the imaginary quadrangle Q 1 . 
         [0023]    The two light sources  140  are fixed on the fixing surface  130 . Because the fixing surface  130  has a substantially same shape as the hexagonal opening  126 , the fixing surface  130  has an axial (not labeled) corresponding to the axial line O 1  and two sides (not labeled) parallel with the axial of the fixing surface  130 . The two light sources  140  are located at two opposite sides of the axial and adjacent to the two parallel sides of the fixing surface  130 , respectively. In this embodiment, each of the light sources  140  is an LED. Alternatively, each of the light sources  140  can also be an LED array containing a number of LEDs. The two light sources  140  are configured for emitting visible light to exterior through the opening  126 . 
         [0024]    The light-pervious cover  160  includes a light-pervious base panel  162  and light-pervious, optical micro-structures  164  formed on the base panel  162 . In an alternative embodiment, the base panel  162  has a same material as and is integrally formed with the micro-structures  164 . That is, the light-pervious cover  162  is a single body of material comprising the base panel  162  and the micro-structures  164 . The micro-structures  164  include two concentric ring-shaped prism groups  166  and  168 . In this embodiment, the two prism groups  166  and  168  are identical with each other. Here only the prism group  166  is described in detail as follows. 
         [0025]    The prism group  166  includes a number of concentric ring-shaped prisms  1662 , with a common central axis O 2 . In this embodiment, the number of the concentric ring-shaped prism  1662  is five. Each of the ring-shaped prisms  1662  has a triangular cross section. The triangle of the ring-shaped prism  1662  has a base  1664  located on the light-pervious plate  162 . The base  1664  has a length in a millimeter level. Preferably, the length of the base  1664  is in the range from 1 millimeter to 1 centimeter. The triangle of each ring-shaped prism  1662  defines two base angles α and β adjacent to the base  1664 , wherein the base angle α is adjacent to the central axis O 2 . In this exemplary embodiment, the base angle α is smaller than the base angle β, thereby the light transmitted through the ring-shaped prism  1662  can be diffused efficiently. Spaces between two adjacent ring-shaped prisms  1662  gradually increase along a radial direction from the central axis O 2  to a periphery of the ring-shaped prisms  1662 , thus causing uniform distribution of the light transmitted through the light-pervious cover  160 . In a preferred embodiment, each of the distances between adjacent ring-shaped prisms  1662  is in the range from 1 millimeter to 1 centimeter. Corresponding to the concentric ring-shaped prism group  166 , the concentric ring-shaped prism group  168  has a central axis O 3 . 
         [0026]    The wall of the reflective housing  120  at the opening  126  and the light-pervious cover  160  abut each other, with the interface sealed therebetween. The sealing may be achieved by, e.g., interference fit or applied transparent adhesive. Thereby, the light-pervious cover  160  is fixed to the wall of the reflective housing  120 . In the illustrated embodiment, the central axis O 2  of the prism group  166  and the central axis O 3  of the prism group  168  pass through the two light sources  140 , respectively. Therefore, the concentric ring-shaped prism groups  166  and  168  can diffuse the light emitted from the light sources  140  efficiently. 
         [0027]    The light-pervious plate  162  defines two curved recesses  170  and  172  in one surface of the light-pervious plate  162  facing toward the fixing surface  130 . The curved recesses  170  and  172  are aligned with the two light sources  140 , respectively. Each of the curved recesses  170  and  172  can be selected from the group consisting of a spherical surface, a cylindrical surface and an aspherical surface. The curved recesses  170  and  172  are configured for diffusing light. 
         [0028]    Referring to  FIG. 4 , a light field of the LED illuminator  100  is shown. Because the distance D 1  between the two parallel sides  1262  and  1264  is larger than the distance D 2  between endpoints that the axial line O 1  passes through, the light field of the LED illuminator  100  has an approximate elongated shape. This light field is advantageous when the LED illuminator  100  is for a street lamp, because more light will be utilized to illuminate the street when the axial line O 1  is perpendicular to a direction which the street extends. Additionally, there is a structure projected from the imaginary quadrangle Q 1 , therefore, more light will be reflected to the opening  126  than by using an illuminator with a quadrangle opening, thereby forming a larger light field. Further more, with diffusion of micro-structures  164  and the curved recesses  170  and  172 , the brightness in the light field distributes uniformly. Referring to  FIG. 5 , a light-distributing curve for illumination of the LED illuminator  100  shows a shape of full width at half maximum. 
         [0029]    Referring to  FIG. 6 , this shows a reflective housing  120 A of a second embodiment. The reflective housing  120 A is differs from the reflective housing  120  in that a reflective surface  222  interconnecting an opening  226  and an fixing surface  224  has a concave cylindrical shape. 
         [0030]    Referring to  FIG. 7 , this shows a reflective housing  120 B of a third embodiment. The reflective housing  120 B is differs from the reflective housing  120  in that a reflective surface  322  interconnecting an opening  326  and an fixing surface  324  is a smooth curved surface. The smooth curved surface of the fixing surface includes a concave surface and a convex surface smoothly adjoining the concave surface. The concave surface is adjacent to the opening  326 , and the convex surface is adjacent to the fixing surface  324 . 
         [0031]    Referring to  FIG. 8 , this shows a light-pervious cover  160 A of a fourth embodiment. The light-pervious cover  160 A differs from the light-pervious cover  160  in that each of concentric ring-shaped prisms  266  has a cross section different from the ring-shaped prism  166 . A contour of the cross section of the ring-shaped prism  266  has a similar shape to the ring-shaped prism  166 , with a difference in that a convex arc  2662  replaces a bevel side of the triangular contour of the ring-shaped prism  1662  that is adjacent to the central axis O 2 . 
         [0032]    Referring to  FIG. 9 , this shows a light-pervious cover  160 B of a fifth embodiment. The light-pervious cover  160 B differs from the light-pervious cover  160  in that each of concentric ring-shaped prisms  366  has a cross section different from the ring-shaped prism  366 . A contour of the cross section of the ring-shaped prism  366  has a similar shape to the ring-shaped prism  166 , with a difference that a convex broken line  3662  replaces the bevel side of the triangular contour of the ring-shaped prism  1662  that is adjacent to the central axis O 2 . The broken line  3662  projects outward the ring-shaped prism  366 . The broken line  3662  includes a plurality of line segments connected one after another in order, thereby forming a substantially curved line curved toward the central axis of the concentric ring-shaped prism  366 . Preferably, the number of the line segments of the broken line  3662  is more than three. 
         [0033]    The ring-shaped prism  266  of the fourth embodiment has a contour including a convex arc line, and ring-shaped prism  366  of the fifth embodiment has a contour of a convex broken line. These shapes cause tops of the ring-shaped prisms to become obtuse. It is clear then, that the obtuse top causes the ring-shaped prism to be stripped from a mold device more easily when the ring-shaped prism is made by a molding process. Also, the obtuse top can prevent from being damaged. 
         [0034]    Referring to  FIG. 10 , this shows a light-pervious cover  160 C of a sixth embodiment. The light-pervious cover  160 C differs from the light-pervious  160  in that a ring-shaped prism group  268  of the light-pervious cover  160 C is non-concentric. In this illustrated embodiment, ring-shaped prisms of the ring-shaped prism group  268  circle one after another in order. That is, in any two ring-shaped prisms of the ring-shaped group  268 , the ring-shaped prism with smaller diameter is circled by the ring-shaped prism with larger diameter. In this exemplary embodiment, centers of the ring-shaped prisms of the ring-shaped prism group  268  are in a same straight line L, and the straight line L is perpendicular to the axial line O 4  of the light-pervious base panel  162  that corresponds to the axial line O 1  in  FIG. 1 . 
         [0035]    Referring to  FIG. 11 , this shows an LED illuminator  400  of a seventh embodiment. The LED illuminator  400  includes a reflective housing (not shown), an LED light source (not shown) and a light-pervious cover  460 . The reflective housing of the LED illuminator  400  has an opening  426  with a shape different from the opening  126 , and a fixing surface (not shown) with a shape different from the fixing surface  130 . The opening  426  has a same shape as the fixing surface of the LED illuminator  400 . Therefore, only the opening  426  is described in detail as follows. The opening  426  has a heptagonal shape having two parallel sides  430  and  432 . Four endpoints of the two parallel sides  430  and  432  cooperatively form an imaginary quadrangle Q 2 . The remaining three endpoints of the opening  426  are located at an exterior of the imaginary quadrangle Q 2 , wherein two of them are adjacent one side of the quadrangle Q 2  and the other one is adjacent to an opposite side of the quadrangle Q 2 , thereby forming two structures projected from the imaginary quadrangle Q 1 . Straight lines parallel with the parallel sides  430  and  432  are intersected by the sides of the opening  426  to form line segments. The longest one of the line segments has a distance D 3 . The distance D 3  is smaller than a distance D 4  between the two parallel sides  430 . The light-pervious cover  460  includes a light-pervious plate  462  and a ring-shaped prism group  464  formed on the light-pervious plate  462 . The light-pervious plate  462  has a same shape as the opening  426  and fixed to the wall of the reflective housing at the opening  426 . The ring-shaped prism group  464  is identical with the ring-shaped prism group  166  of the first embodiment. 
         [0036]    Referring to  FIG. 12 , this shows a light field of the LED illuminator  400  is shown. As described above, the distance D 3  is smaller than the distance D 4 , therefore, the light field of the LED illuminator  400  has an approximate elongated shape. This light field is advantageous when the LED illuminator  400  is for a street lamp, because more light will be utilized to illuminate the street. Additionally, there are structures projected from the imaginary quadrangle Q 2 , therefore, more light will be reflected to the opening  426  than by using an illuminator with a quadrangle opening, thereby forming a larger light field. Further more, with diffusion of ring-shaped prism group  464 , the brightness in the light field distributes uniformly. 
         [0037]    It can be understood that the above-described embodiment are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments and methods without departing from the spirit of the disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.