Patent Publication Number: US-2013228811-A1

Title: Light source device having light emitting diode

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to illumination, and more particularly to an LED (light emitting diode) light source device having a uniform distribution of light output. 
     2. Description of Related Art 
     LEDs have been widely promoted as light sources of electronic devices owing to many advantages, such as high luminosity, low operational voltage and low power consumption. However, as a point light source, a light-emitting angle of the LED is only 120°, and a light field of the LED is not uniform. 
     Therefore, an LED light source device which is capable of overcoming the above described shortcomings is desired. 
    
    
     
       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  shows a schematic, cross sectional view of an LED light source device in accordance with a first embodiment of the present disclosure. 
         FIG. 2  shows a schematic, cross sectional view of an LED light source device in accordance with a second embodiment of the present disclosure. 
         FIG. 3  shows a schematic, cross sectional view of an LED light source device in accordance with a third embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , an LED light source device  1  in accordance with a first embodiment of the present disclosure includes an LED light source  10 , a first powder layer  20 , a lamp shell  30  covering the LED light source  10  and the first powder layer  20 , and a second powder layer  40  coated on an inner surface  31  of the lamp shell  30 . 
     In this embodiment, the LED light source  10  is an LED package, and includes a substrate  11  with an electrode structure  12 , an LED chip  13  electrically connected with the electrode structure  12 , a reflection layer  14  surrounding the LED chip  13 , and an encapsulation layer  15  sealing the LED chip  13 . 
     The first powder layer  20  is located on a light path of the LED light source  10  and spaced from the LED light source  10 . In this embodiment, the first powder layer  20  has a plate shape, and includes a lower surface  21  facing the LED light source  10 , and an upper surface  22  opposite to the lower surface  21 . The first powder layer  20  has a characteristic of scattering light. Light emitted from the LED light source  10  is scattered by the first powder layer  20  into multi-directional light, so the light-emitting angle of the LED light source  10  is increased, and a light intensity distribution of the light field of the LED light source  10  is uniform. The first powder layer  20  can be made of SiO 2  powder, Al 2 O 3  powder, silicate powder or a mixture thereof. Alternatively, the first powder layer  20  can be directly attached on the encapsulation layer  15  of the LED light source  10 . In addition, the first powder layer  20  can be shaped into a block of other shape. 
     The lamp shell  30  is located outside of the LED light source  10  and the first powder layer  20 , and includes an inner surface  31 . The inner surface  31  defines a receiving room  32 . In this embodiment, the lamp shell  30  is transparent or translucent. The LED light source  10  and the first powder layer  20  are received in the receiving room  32 . The lamp shell  30  has a shape of a hollow cube, with an opening  33  defined in a bottom side thereof. 
     The second powder layer  40  is coated on the inner surface  31  of the lamp shell  30 , and has a characteristic of scattering light. The second powder layer  40  can be made of SiO 2 powder, Al 2 O 3  powder, silicate powder or a mixture thereof. 
     During operation of the LED light source  10 , the light emitted from the LED light source  10  travels toward the lower surface  21  of the first powder layer  20 . A part of the light is reflected by the lower surface  21  to travel slantwise downwardly toward the second powder layer  40 , from where the light is reflected by the second powder layer  40  out of the lamp shell  30  via the opening  33  or refracted by the second powder layer  40  to radiate out of the lamp shell  30  via the lamp shell  30 . Due to the light scattering characteristic of the first powder layer  20 , another part of the light travelling toward the lower surface  21  is refracted to the upper surface  22  of the first powder layer  20  when it is incident onto the first powder layer  20 . The another part of the light successively passes through the upper surface  22  of the first powder layer  20 , and is finally projected upwardly towards the second powder layer  40  via the receiving room  32 . At the second powder layer  40 , the light is scattered thereby to radiate out of the lamp shell  30  via the lamp shell  30  or the opening  33 . After being scattered by the first powder layer  20  and the second powder layer  40 , the light travels outward via the lamp shell  30  and the opening  33 , along various directions. Therefore, the light-emitting angle of the LED light source device  1  is increased, and a light intensity distribution of the light field of the LED light source device  1  is uniform. 
     Additionally, the first powder layer  20  and the second powder layer  40  can be respectively made of a single color phosphor material, or made of multi-color phosphor materials. The phosphor materials of the first powder layer  20  and the second powder layer  40  can be the same or different, according to actual requirement. The first and second powder layers  20 ,  40  can be alternately stacked by phosphor materials and powder materials, such as SiO 2 , Al 2 O 3  or silicate. 
     Referring to  FIG. 2 , an LED light source device  1  a in accordance with a second embodiment of the present disclosure is similar to the LED light source device  1  in the first embodiment. Different from the LED light source device  1  of the first embodiment, the LED light source device  1  a includes a closed lamp shell  30   a.  The lamp shell  30   a  has an inner surface  31   a,  and the inner surface  31   a  defines a closed receiving room  32   a.  The second powder layer  40   a  is coated on the inner surface  31   a.    
     During operation of the LED light source  10 , the light emitted from the LED light source  10  travels toward the lower surface  21  of the first powder layer  20 . A part of the light is reflected by the lower surface  21  to travel slantwise downwardly toward the second powder layer  40   a,  from where the light is reflected by the second powder layer  40   a  to another part of the second powder layer  40  or refracted by the second powder layer  40   a  to radiate out of the lamp shell  30   a  via the lamp shell  30   a.  Due to the light scattering characteristic of the first powder layer  20 , another part of the light travelling toward the lower surface  21  is refracted to the upper surface  22  of the first powder layer  20  when it is incident onto the first powder layer  20 . The another part of the light successively passes through the upper surface  22  of the first powder layer  20 , and is finally projected upwardly towards the second powder layer  40   a  via the receiving room  32   a.  At the second powder layer  40   a,  the light is scattered thereby to radiate out of the lamp shell  30   a  via the lamp shell  30   a.  After being scattered by the first powder layer  20  and the second powder layer  40   a,  the light travels outward via the lamp shell  30   a  along various directions. Therefore, the light-emitting angle of the LED light source device  1   a  is increased, and a light intensity distribution of the light field of the LED light source device  1   a  is uniform. 
     Referring to  FIG. 3 , an LED light source device  1   b  in accordance with a third embodiment of the present disclosure is similar to the LED light source device  1  in the first embodiment. Different from the LED light source device  1  of the first embodiment, the LED light source  10  is located outside of the receiving room  32  of the lamp shell  30 , and adjacent to the opening  33 . 
     During operation of the LED light source  10 , the light emitted from the LED light source  10  travels toward the lower surface  21  of the first powder layer  20 . A part of the light emitted from the LED light source  10  is reflected by the lower surface  21  to an exterior of the LED light source device  1   b . Due to the light scattering characteristic of the first powder layer  20 , another part of the light travelling toward the lower surface  21  is refracted to the upper surface  22  of the first powder layer  20  when it is incident onto the first powder layer  20 . The another part of the light successively passes through the upper surface  22  of the first powder layer  20 , and is finally projected upwardly towards the second powder layer  40  via the receiving room  32 . At the second powder layer  40   a , the light is scattered thereby to radiate out of the lamp shell  30  via the lamp shell  30  or the opening  33 . After being scattered by the first powder layer  20  and the second powder layer  40 , the light travels outward via the lamp shell  30  and the opening  33  along various directions. Therefore, the light-emitting angle of the LED light source device lb is increased, and a light intensity distribution of the light field of the LED light source device  1   b  is uniform. 
       FIGS. 1-3  only succinctly illustrate the scattering paths of the light emitted from the LED light source  10 , without introducing other structures of the LED light source device  1 ,  1   a,    1   b.  Thus, the LED light source device  1 ,  1   a,    1   b  can also include other unmentioned structures, such as a lamp holder. Further, the lamp shell  30 ,  30   a  is not limited to be a hollow cube, and for example, the lamp shell  30 ,  30   a  can also be a hollow globe or a hollow ellipsoid. 
     Particular embodiments are shown and described by way of illustration only. The principles and the features of the present disclosure may be employed in various and numerous embodiments thereof without departing from the scope of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.