Patent Publication Number: US-2007103900-A1

Title: White light emitting device

Description:
BACKGROUND OF THE INVENTION  
      a) Field of the Invention  
      The present invention relates to a white light emitting and more particularly to a device by which a second mixed light with a high rendering effect can be released.  
      b) Description of the Prior Art  
      A typical example of a conventional light emitting device includes a Taiwan Patent publication No. 383508, “Light Emitting and Display Devices,” applied by the Japanese Nichia Corporation, wherein only a blue light semiconductor of a single blue light source is used to emit a blue light for exciting a yellow illumination layer, so as to display a white light of different wavelength. As the invention only mixes a light of single wavelength with the blue light whose portion is not excited, the rendering effect is inferior, i.e., the white light is distorted and not pure.  
     SUMMARY OF THE INVENTION  
      The primary object of present invention is to provide a white light emitting device, and in particular, a device which excites an illuminator, which is made by mixing a greenish yellow illumination material with a blue illumination material, by a blue light emitted from a blue light LED, to generate a first mixed light comprising the greenish yellow light and the blue light. The first mixed light is mixed with a red light LED to form a second mixed light having a high rendering effect and saturation of color.  
      Another object of the present invention is to provide a white light emitting device, wherein an illuminator, which is formed by mixing a greenish yellow illumination material, a blue illumination material, and a red illumination material, is excited by a blue light emitted from a blue light LED to generate a first mixed light comprising the greenish yellow light, the blue light, and the red light. The first mixed light is mixed with a red light emitted from a red light LED to form a second mixed light having a high rendering effect and saturation of color.  
      Still another object of the present invention is to provide a white light emitting device, wherein a second mixed light having a high rendering effect and saturation of color can be formed by mixing a greenish yellow light, which is emitted from a greenish yellow LED added to light emitting elements, with a first mixed light.  
      To enable a further understanding of the said objectives and the technological methods of the invention herein, the brief description of the drawings below is followed by the detailed description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a cross sectional view of a device of the present invention.  
       FIG. 2  shows a flow diagram of a color rendering of the present invention.  
       FIG. 3  shows a curve of independent wavelengths of an active light emitting LED and a passive light emitting illuminator of the present invention.  
       FIG. 4  shows a curve of wavelength of a second mixed light of the present invention.  
       FIG. 5  shows a flow diagram of a color rendering after adding a red illumination material to an illuminator of the present invention.  
       FIG. 6  shows a curve comparing a wavelength of a second mixed light with a waveform of daylight of the present invention.  
       FIG. 7  shows a curve of wavelength of a second mixed light after mixing a passive red light source and a greenish yellow light source of the present invention.  
       FIG. 8  shows a flow diagram of another implementation of the present invention.  
       FIG. 9  shows a cross sectional view of another implementation of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is to provide a white light emitting device, as shown in  FIG. 1  and  FIG. 2 , which includes at least more than one blue light LED  10  which can emit a blue light  15 , more than one red light LED  20  which can emit a red light, and an illuminator  50  made by uniformly mixing a greenish yellow illumination material  52 , a blue illumination material  53 , and a transparent glue (not shown in the drawings), wherein the greenish yellow illumination material  52  is made by an Aluminate material using cerium (Ce) as its activator, and the blue illumination material  53  is made by an Aluminate material using europium (Eu) as its activator.  
      The illuminator  50  is covered on an upper surface of the blue light LED  10 , in order to absorb the blue light  15 , such that the illuminator  50  can be excited to a first mixed light  80  having a wavelength different than that of the blue light  15 . A second mixed light  90  is released by mixing the first mixed light  80  with the red light  25  emitted from the red light LED  20 .  
      The greenish yellow illumination material  52  in the illuminator  50  is excited to a greenish yellow light  521  with a wavelength specified to be between 500 nm and 585 nm, by the blue light  15  (as shown in  FIG. 3 ). A blue light  531  emitted from the blue illumination material  53  which is excited by the blue light  15  has a specified wavelength between 450 nm and 500 nm. The first mixed light  80  is formed by mixing these two lights of different colors.  
      Accordingly, as shown in  FIG. 8 , a red illumination material  51  can be added to the illuminator  50  to be mixed with the original greenish yellow illumination material  52  and the blue illumination material  53 . A red light  511  emitted from the red illumination material  51  which is excited by the blue light  15  has a specified wavelength between 585 nm and 700 nm.  
      Accordingly, as shown in  FIG. 1 , the blue light LED  10  and the red light LED  20  are installed in a reflection slot  61  of a light reflection cap  60 , the illumination layer  50  made by mixing the greenish yellow illumination material  52  and the blue illumination material  53  is covered on the blue light LED  10 , and a transparent glue  65  is filled in the slot  61  to cover the illumination layer  50  and the red light LED  20 .  
      Referring to  FIG. 1  and  FIG. 2 , the present invention is to provide a white light emitting device which includes at least more than one blue light LED  10  which can emit a blue light  15 , more than one red light LED  20  which can emit a red light  25 , more than one greenish yellow light LED  30  which can emit a greenish yellow light  35  (as shown in  FIG. 8 ), and an illuminator  50  which is made by uniformly mixing a greenish yellow illumination material  52 , a blue illumination material  53 , and a transparent glue (not shown in the drawings). The greenish yellow illumination material  52  is made by an Aluminate material using cerium (Ce) as its activator, and the blue illumination material  53  is made by an Alluminate material using europium (Eu) as its acticator. The illuminator  50  is covered on an upper surface of the blue light LED  10  to absorb the blue light  15 , such that the illuminator  50  can be excited to a first mixed light  80  having a wavelength different than that of the blue light  15 . A second mixed light  90  is then released by mixing the first mixed light  80 , the red light  25 , and the greenish yellow light  35 . The greenish yellow light  521  emitted from the greenish illumination material  52  in the illuminator  50  which is excited by the blue light  15  has a specified wavelength between 500 nm and 585 nm (as shown in  FIG. 3 ). The blue light  531  emitted by the blue illumination material  53  which is excited by the blue light  15  has a specified wavelength between 450 nm and 500 nm. The first mixed light  80  is formed by mixing these two lights of different colors.  
      Accordingly, as shown in  FIG. 9 , the blue light LED  10 , the red light LED  20 , and the greenish yellow light LED  30  are installed in a slot  61  of a light reflection cap  60 , and the illumination layer  50  made by mixing the greenish yellow illumination material  52  with the blue illumination material  53  is filled in the slot  61 .  
      Accordingly, the blue light  15  emitted from the blue light LED  10  has a wavelength between 400 nm and 480 nm, the red light  511  emitted from the red light LED  25  has a wavelength between 585 nm and 780 nm, and the greenish yellow light  35  emitted from the greenish yellow light LED  30  has a wavelength between 500 nm and 585 nm.  
      Accordingly, the greenish yellow illumination material  52 , the blue illumination material  53 , and the red illumination material  51  in the illuminator  50  can be chosen from one of or a combination of the following materials: (1) the Aluminate series, (2) the Silicate series, (3) the Phosphate series, (4) the Bornate series, and (5) the Sulfide series.  
      Referring to  FIG. 1 , a blue light LED  10  and a red light LED  20  are installed in a light reflection cap  60  whose lower side is connected to wire frames  62 ,  63  of positive and negative electrodes. An illuminator  50  can be covered on an upper surface of the blue light LED  10 , and a transparent glue  65  is sealed in a slot  61  of the light reflection cap  60 , thereby packaging the blue light LED  10  and the red light LED  20 . As shown in  FIG. 2 , by putting the electrodes to the blue light LED  10  and the red light LED  20 , the blue light LED  10  will emit a blue light  15  with a wavelength between 400 nm and 480 nm. The illuminator  50  is made by mixing a greenish yellow illumination material  52  and a blue illumination material  53 , wherein the greenish yellow illumination material  52  absorbs a portion of blue light  15  to excite to a greenish yellow light with a wavelength between 500 nm and 585 nm, and the blue illumination material  53  absorbs a portion of blue light  15  to excite to a blue light  531  with a wavelength between 450 nm and 500 nm. The excited greenish yellow light  521  and the blue light  531  are mixed to form a first mixed light to be released. The red light LED  20  emits a red light  25  with a wavelength between 585 nm and 780 nm, which will be mixed with the first mixed light  80  to form a second mixed light  90 .  
      Referring to  FIG. 3 , it shows a curve of wave forms of the independent blue light  15 , the red light  25 , the excited greenish yellow light  521 , and the excited blue light  531  before mixing. It is concluded that all of the blue light  15 , the red light  25 , the passive greenish yellow light  521  and blue light  531  have a specific wavelength and luminous intensity.  
      Referring to  FIG. 4 , it shows a curve of the blue light  15 , the red light  25 , the greenish yellow light  521 , and the blue light  531  after mixing. The second mixed light  90  is formed by mixing, with an average wavelength between 400 nm and 700 nm. By comparing the second mixed light  90  with a hypothetical daylight spectrum  95  (or the natural light), it is concluded that the second mixed light  90  and the daylight spectrum  95  have an extremely high rendering effect in the visible light region of the wavelength between 400 nm and 680 nm. Therefore, the second mixed light  90  achieved by the present invention has a color rendering effect (such as a white light) which is closer to the natural light, and is provided with an enhanced saturation of color.  
      The illuminator  50  is primarily made by uniformly mixing the greenish yellow illumination material  52  with the blue illumination material  53 , which will generate a different reaction in light enabling color according to a variation of proportion of their elements. The light enabling color of the greenish yellow illumination material  52  is greenish yellow, and the light enabling color of the blue illumination material  53  is blue. Therefore, a same material can be chosen for the greenish yellow illumination material  52  and the blue illumination material  53 , but different light enabling colors will be generated if the proportions are different. The material of illuminator  50  of present invention can be chosen from one of or a combination of a plurality of the following elements: (1) the Aluminate series, (2) the Silicate series, (3) the Phosphate series, (4) the Bornate series, and (5) the Sulfide series.  
      Referring to  FIG. 5 , another red illumination material  51  made by MgF 2 , MgO, and GeO 2 :Mn can be added to the illuminator  50 , to be mixed with the aforementioned greenish yellow illumination material  52  and blue illumination material  53 , such that when the illuminator  50  is excited by the blue light  15 , a red light  511  will be excited and mixed with the blue light  531  and the greenish yellow light  521 , to form a first mixed light  80 ′. Therefore, the first mixed light  80 ′ is provided with the red light  511 , the blue light  531 , and the greenish yellow light  521  of different wavelengths, wherein the wavelength of red light  511  lies in between 585 nm and 700 nm. Referring to  FIG. 6 , it shows the ranges of wavelengths and relative luminous intensities of independent blue light  15 , red light  25 , greenish yellow light  35 , excited blue light  531 , excited greenish yellow light  521 , and excited red light  511 , before mixing. It can be concluded that all of these six different lights have a specific wavelength and luminous intensity.  
      Referring to  FIG. 9 , the illumination layer  50  is directly sealed on a top of greenish yellow light LED  30 , red light LED  20 , and blue light LED  10 . In the present invention, a special greenish yellow light LED  30  with a specified wavelength between 500 nm and 580 nm is added in the light reflection cap  60 , to serve as another source of greenish yellow light  35 . As shown in  FIG. 8  and  FIG. 9 , a second mixed light  90 ′, whose wavelength is shown in  FIG. 7 , can be formed by mixing the greenish yellow light  35 , the red light  25 , and the blue light  15  with the aforementioned first mixed light  80 ′. By comparing the wave forms of the second mixed lights  90 ′,  90  in  FIG. 7  and  FIG. 4 , it is concluded that a portion of the waveform intensity of red light  25  and the waveform intensity of greenish yellow light  35  are added to the second mixed light  90 ′ in  FIG. 7 . Therefore, by comparing the second mixed light  90 ′ in  FIG. 7  with the daylight spectrum  95  (or natural light), it is concluded that the second mixed light  90 ′ is very similar to the daylight spectrum  95  in the visible light region of a wavelength between 400 nm and 680 nm. Accordingly, the second mixed light  90 ′ has the color (such as a white light) rendering effect closer to the natural light, and is provided with an enhanced saturation of color.  
      It is of course to be understood that the embodiments described herein is merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.