Patent Publication Number: US-2007103931-A1

Title: Assembly device for a sidelight light source module and liquid crystal panel

Description:
BACKGROUND OF THE INVENTION  
      (a) Field of the Invention  
      The present invention relates to an assembly device for a sidelight light source module and liquid crystal panel, which particularly provides a white light backlight source having superior color rendering for a liquid crystal panel.  
      (b) Description of the Prior Art  
      Conventional structures for assembly of a liquid crystal panel and backlight source module include Taiwan Utility Model Reg. No. M245448, entitled “Light source module for a liquid crystal display”, which uses a light source structured from an ultraviolet (UV) LED and red, blue and green (R, B, G) fluorescent substances. However, a shortcoming of such a structure is that the ultraviolet light damages current, extensively used epoxy resin structures, causing a problem of final white light attenuation, thereby resulting in a relatively dull white light. More particularly, a covering layer used in the above cited patent is compounded from red, green and blue color fluorescent substances, which causes another shortcoming in that the ratio of the three colors and the manufacturing process are difficult to control.  
      Furthermore, claim 5 of the above cited patent discloses that the light-emitting diode is a blue light LED, and that the fluorescent powders are red and green fluorescent substances. However, ratio of the red fluorescent powder and the green fluorescent powder and the manufacturing process are difficult to control, thereby making uniformity of the mixed light (that is, white light) also difficult to control, thereby finally producing poor color rendering of the white light displayed by the liquid crystal panel.  
      Taiwan Utility Model Reg. No. M251143, entitled “Light source device for a liquid crystal screen”, uses a light source that is blue light or UV light of wavelength between 202 mm and 500 mm, which serves as a single light source. However, the light source lacks a red light spectrum portion, which results in poor color rendering and uniformity of the mixed white light (that is, mixed light) emitted by the fluorescent screen, and is seen by the human eye as impure white light.  
      Taiwan patent publication No. I228837, entitled “Light-emitting Device”, issued to the inventor of the present invention, is a white light light-emitting diode that uses blue light light-emitting chips and red light light-emitting chips as two light sources, and a fluorescent layer veneers the blue light light-emitting chips and the red light emitting-emitting chips. The blue light source excites the fluorescent layer to emit a green light, which is then mixed with blue and red light to form white light. The above cited patent effectively overcomes the problem produced by the difficult control of the ratio and manufacturing process of mixing different color fluorescent powders of the aforementioned patent by replacing the conventional red fluorescent powder with a red light-emitting diode, which further enables the induced luminescent fluorescent layer material to be a single color material.  
      Such a design resolves the problem of difficult control of the ratio and manufacturing process of mixing different colors, and can further control an induced luminescent single excited light wavelength (that is, green light wavelength). Furthermore, the above patent uses a mixture of three colored lights including red light, excited light emitted by the red light-emitting diode and blue light, thereby obtaining white light having better color rendering. However, embodiments of the cited patent are limited to new designs of white light light-emitting diodes, and with regard to application in devices assembled with a liquid crystal panel and backlight module, the cited patent has no extended assembled embodiments.  
     SUMMARY OF THE INVENTION  
      A primary objective of the present invention is to provide an assembly device for a sidelight light source module and liquid crystal panel that enables easy control of and achieves superior color rendering and uniformity of a transmitted backlight white light.  
      Another objective of the present invention is to provide the assembly device for a sidelight light source module and liquid crystal panel with a fluorescent layer used by a backlight source module that is fabricated from induced luminescent material, which enables easy control of the excited light wavelengths, thereby achieving easy control of the color rendering and uniformity of the backlight white light source.  
      Yet another objective of the present invention is to provide the assembly device for a sidelight light source module and liquid crystal panel with an easily replaceable light diffuser plate coated with the fluorescent layer, thereby providing renewable functionality.  
      To enable a further understanding of said objectives and the technological methods of the invention herein, brief description of the drawings is provided below followed by detailed description of the preferred embodiments.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a cross-sectional schematic view according to the present invention.  
       FIG. 2  shows a cross-sectional schematic view of another embodiment according to the present invention.  
       FIG. 3  shows a cross-sectional schematic view of another embodiment according to the present invention.  
       FIG. 4  shows a cross-sectional schematic view of another embodiment according to the present invention.  
       FIG. 5  shows a cross-sectional schematic view of another embodiment according to the present invention.  
       FIG. 6  shows a cross-sectional schematic view of another embodiment according to the present invention.  
       FIG. 7  shows a partial cross-sectional view of a light source module according to the present invention.  
       FIG. 8  shows a partial cross-sectional view of an embodiment of a light source module according to the present invention.  
       FIG. 9  shows a partial cross-sectional view of an embodiment of a light source module according to the present invention.  
       FIG. 10  shows a partial cross-sectional view of an embodiment of a light source module according to the present invention.  
       FIG. 11  shows a partial cross-sectional view of an embodiment of a light source module according to the present invention.  
       FIG. 12  shows an elevational view of the light source module according to the present invention.  
       FIG. 13  shows an elevational view of another embodiment of the light source module according to the present invention.  
       FIG. 14  shows an elevational view of another embodiment of the light source module according to the present invention.  
       FIG. 15  shows a cross-sectional view of an embodiment of a light diffuser plate according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIGS. 1 and 9 , the assembly device for a sidelight light source module and liquid crystal panel of the present invention comprises:  
      a liquid crystal panel  10 ;  
      a light guide panel  20  positioned below the liquid crystal panel  10 ;  
      a light reflecting plate  30  positioned below the light guide panel  20 ;  
      a light source module  40  installed at a side of the light guide panel  20 ; wherein the light source module comprises:  
      a circuit board  42 , on top of which is soldered at least more than one blue light chip  55  that serves as a blue light B light-emitting source and at least more than one red light chip  65  that serves as a red light R light-emitting source, wherein the blue light chips  55  and the red light chips  65  are reciprocally adjacent;  
      a luminescence fluorescent layer  70  is positioned on top of the blue light chip  55  and the red light chip  65 , wherein the blue light B is primarily used to excite the fluorescent layer  70  and emit excited light G having wavelength between 500 and 570 mm; mixed light consisting of the excited light G, the blue light B and the red light R is transmitted out the fluorescent layer  70  and forms a white light W light source that is guided by the light guide panel  20  into the light reflecting plate  30 , where it undergoes refraction and then transmitted out the liquid crystal panel  10 .  
      Referring again to  FIGS. 1 and 9 , the fluorescent layer  70  encapsulates the adjacent blue light chip  55  and red light chip  65 .  
      Referring to  FIGS. 2 and 8 , wherein a light diffuser plate  15  is disposed on a top portion of the light guide panel  20 . A uniform coating of the fluorescent layer  70  is coated on a surface of the light diffuser plate  15 . The blue light chips  55  and the red light chips  65  soldered to the circuit board  42  are covered with transparent rubber layers  75 .  
      Referring again to  FIG. 8 , wherein the blue light chips  55  and the red light chips  65  are independently disposed in grooves  61 , ( 61 ) of light reflecting covers  60 , ( 60 ) respectively. Electrode leads  62 ,  64  of the two light reflecting covers  60 , ( 60 ) are respectively soldered to the circuit board  42 . A separation distance L between the two reflecting covers  60 , ( 60 ) is controlled to be within 1 mm. The grooves  61 , ( 61 ) of the two light reflecting covers  60 , ( 60 ) are respectively filled with the transparent rubber layer  75  and a surface of the circuit board  42  is coated with the transparent rubber layer  75 .  
      Referring to  FIGS. 1, 2 ,  3 ,  4 ,  5 ,  7  and  9 , fluorescent powder of the fluorescent layer  70  can be composed of substances including yttrium aluminum garnet or silicates (SmOn 4− ) or borates (BxOy 3− ).  
      Referring again to  FIG. 9 , wherein the blue light chip  55  and the red light chip  65  are connected in the groove  61  of the same light reflecting cover  60 . The groove  61  can be filled with the fluorescent layer  70 , and the two electrode leads  62 ,  64  are soldered to the circuit board  42 .  
      Referring again to  FIGS. 1, 2 ,  3 ,  4 ,  5 ,  7  and  9 , wherein the substances constituting the fluorescent powder  70  can be compounded from one or two or three of the following compounds: 
          cerium activator containing Y and Al yttrium aluminum garnet (YAG:Ce 3+ );     europium activated garnet (YAG:Eu 2+/3+ );     terbium activated garnet (YAG:Tb 3+ ).        

      Referring to  FIG. 6 , wherein a transparent light intensifying film  125  or a light intensifying prism plate is additionally disposed between the liquid crystal panel  10  and the light diffuser plate  15 .  
      Referring to  FIGS. 12 and 13 , wherein a plurality of the paired blue light chips  55  and the red light chips  65  are arranged to form at least one row on the circuit board  42 , and are soldered on the circuit board  42  using a one-dimensional straight line array arrangement.  
      Referring to  FIG. 15 , wherein a bottom surface of the light diffuser plate  15  is formed with a prism surface  156  consisting of adjoining ridges and valleys having included angle θ smaller than 90°.  
      Referring to  FIG. 12 , which shows a liquid crystal panel  10 , a light diffuser plate  15  and a light source module  40  having rectangular shapes of relatively small area that are applicable for use in small-scale liquid crystal screens. Referring to  FIG. 13 , which shows the liquid crystal panel  10 , the light diffuser plate  15  and the light source module  40  having rectangular square shapes of relatively large area that are applicable for use in liquid crystal screens of relatively large dimensions.  
      Referring to  FIGS. 1 and 9 , which shows a blue light chip  55  and a red light chip  65  encapsulated on a light source module  40  with a fluorescent layer  70 . Moreover, the blue light chip  55  and the red light chip  65  are arranged in pairs, each of which are soldered in a groove  61  of a light reflecting cover  60 . When electricity is supplied to electrode leads  62 ,  64 , the blue light chips  55  and the red light chips  65  are actuated and simultaneously emit blue light B and red light R respectively. The blue light B primarily excites the fluorescent layer  70 , thereby causing the fluorescent layer  70  to emit excited light G having wavelength between 500 and 570 mm, which is defined to be green light. Hence, the mixed light of blue light B, red light R and excited light G defined as white light W is guided by a light guide panel  20  to a light reflecting plate  30 , as depicted in  FIG. 1 , where it undergoes reflection and is transmitted through a light diffuser plate  15  and out the liquid crystal panel  10 , thereby forming a backlight source for the liquid crystal panel  10 . This embodiment primarily describes a configuration whereby the fluorescent layer  70  directly covers the blue light chip  55  and the red light chip  65 .  
      Referring to  FIGS. 2 and 12 , which shows an embodiment that primarily depicts a configuration whereby the fluorescent layer  70  is attached to different positions, and is not limited to being attached on top of the blue and red light chips  55 ,  65 . The fluorescent layer  70  is coated on a top surface of the light diffuser plate  15 , and the blue and red light chips  55 ,  65  on the light source module  40  are not covered by the fluorescent layer  70 . The blue and red light chips  55 ,  65  are actuated by a circuit of the circuit board  42  and simultaneously emit the blue light B and the red light R respectively, which are guided by the light guide panel  20  into the light reflecting plate  30 , where the blue light B and the red light R are reflected toward the light diffuser plate  15  and undergo uniform diffusion thereat, whereafter the blue light B excites the fluorescent layer  70 , which emits excited light G that is then mixed with the blue light B and the red light R to form the white light W that is transmitted out the liquid crystal panel  10 .  
      Referring to  FIG. 3 , which shows the fluorescent layer  70  coated on a bottom surface of the light diffuser plate  15 , and the blue and red light chips  55 ,  65  within the light source module  40  are similarly not covered by the fluorescent layer  70 . The blue light B excites the fluorescent layer  70  to produce the excited light G, which is transmitted through the light diffuser plate  15 , and the white light W formed from mixing the blue light B and the red light R and the excited light G is transmitted out the liquid crystal panel  10 .  
      Referring to  FIG. 4 , which shows the fluorescent layer  70  coated on both the top surface and the bottom surface of the light diffuser plate  15 , which is a preferred practicable embodiment of the present invention.  
      Referring to  FIG. 5 , fluorescent powder is uniformly mixed into material of the light diffuser plate  15 , thereby enabling the light diffuser plate  15  to simultaneously serve as the luminescence fluorescent layer  70 . With such a configuration, the light source module  40  is not covered by the fluorescent layer  70 , thus, the light source module  40  transmits the blue light B and the red light R, which the light guide panel  20  guides into the light reflecting plate  30 , where they are reflected towards the light diffuser plate  15 . The light diffuser plate  15  serves as the fluorescent layer  70  and is excited by the blue light B and emits the excited light G, and the white light W formed from mixing the blue light B and the red light R and the excited light G is transmitted out the liquid crystal panel  10 .  
      Referring to  FIG. 6 , which shows a light intensifying film  125  or a prism plate attached to the top surface of the light diffuser plate  15 , thereby achieving the objective of intensifying the light. Such an embodiment has the fluorescent layer  70  fabricated into the light source module  40   
      Referring to  FIG. 7 , wherein the blue light chip  55  is installed in the groove  61  of the independent light reflecting cover  60 , and the red light chip  65  is installed in the groove  61  of the other independent light reflecting cover  60 . A distance L between the two reflecting covers  60  is best controlled to be between 1 and 2 mm. The groove  61  with the blue light chip  55  disposed therein can be further filled with the fluorescent layer  70 , and the groove  61  with the red light chip  65  disposed therein is filled with a transparent rubber layer  75 , and the light diffuser plate  15  is not coated with the fluorescent layer  70 , as depicted in  FIG. 1 . Hence, the mixed light (that is, the white light W) emitted, consisting of the blue, red and excited lights (B, R and G respectively), is transmitted out the liquid crystal panel  10 .  
      Referring to  FIG. 8 , which shows the blue light chip  55  and the red light chip  65  installed into the grooves  61 , ( 61 ) of the two independent light reflecting covers  60 , ( 60 ) respectively. The two grooves  61 , ( 61 ) are respectively filled with the transparent rubber layer  75 , ( 75 ). This embodiment describes a configuration whereby the light source module  40  is not coated by the fluorescent layer  70 , and the fluorescent layer  70  is coated onto the surface of the light diffuser plate  15 , as depicted in  FIGS. 2, 3 ,  4  and  5 . Hence, the light source modules  40  emits the blue light B and the red light R, wherein the blue light B excites the fluorescent layer  70  coated on the surface of the light diffuser plates  15 , as depicted in  FIGS. 2, 3 ,  4  and  5 , and the excited light G excited therefrom enables the white light W to be transmitted out the liquid crystal panel  10 .  
      Referring to  FIG. 9 , which shows the blue light chip  55  and the red light chip  65  installed in the same groove  61  of the light reflecting cover  60 . The fluorescent layer  70  is filled in the groove  61  and covers the blue light chip  55  and the red light chip  65 . The light diffuser plate  15  is not coated with the fluorescent layer  70 , as depicted in  FIG. 1 , thus, the mixed white light W, consisting of the blue, red and excited lights (B, R and G respectively), emitted by the light source module  40  forms a backlight source for the liquid crystal panel  10 .  
      Referring to  FIG. 10 , which shows the blue and red light chips  55 ,  65  directly soldered to the circuit board  42 . The fluorescent layer  70  directly encapsulates the blue and red light chips  55 ,  65 , or the transparent rubber layer  75  can encapsulate the blue and red light chips  55 , 65 . When the blue and red light chips  55 ,  65  have been encapsulated by the fluorescent layer  70 , then the light diffuser plate  15  does not have a coating of the fluorescent layer  70 , as depicted in  FIG. 1 . However, when the blue and red light chips  55 ,  65  have been encapsulated by the transparent rubber layer  75 , then the light diffuser plate  15  is coated with the fluorescent layer  70  (as depicted in  FIGS. 2, 3 ,  4  and  5 ).  
      Referring to  FIG. 11 , which shows the blue light chip  55  and the red light chip  65  installed in the groove  61  of the light reflecting cover  60 , and the transparent rubber layer  75  encapsulates the groove  61 . The light source module  40  is not covered by the fluorescent layer  70 ; instead, the fluorescent layer  70  is disposed on the surface of the light diffuser plate  15  (as depicted in  FIGS. 2, 3 ,  4  and  5 ).  
      Referring to  FIG. 15 , the light diffuser plate  15  is formed with a concavo-convex prism surface  156  consisting of adjoining ridges and valleys that achieve the objective of intensifying light.  
      The present invention is characterized in that the light source module  40  uses light-emitting diodes including the blue light chips  55  and the red light chips  65 , which function in coordination with the fluorescent layers  70  coated at different locations, thereby producing a mixed light consisting of the blue light B, the red light R and the excited light G having superior uniformity and color rendering. The fluorescent layer  70  is fabricated as a single luminescence colored material, eliminating the need for mixing with other different colored fluorescent substances, and further eliminates the concern arising from the problem of ratio control of different fluorescent powders. Moreover, the manufacturing process is easy to control, and more particularly the red light chips  65  in the light source are light-emitting diodes, enabling easy control of wavelength and intensity of the red light R emitted therefrom.  
      In conclusion, the sidelight light source of the present invention used in the field of liquid crystal panels achieves a backlight light source—white light W having superior color rendering and uniformity. Moreover, considerable originality and advancement and commercial utility value of the present invention clearly comply with essential elements as required for a new patent application. Accordingly, a new patent application is proposed herein.  
      It is of course to be understood that the embodiments described herein are 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.