Patent Publication Number: US-2007103930-A1

Title: Assembled device of a light module and a liquid crystal panel

Description:
BACKGROUND OF THE INVENTION  
      a) Field of the Invention  
      The present invention relates to an assembled device of a light module and a liquid crystal panel and more particularly to a device wherein a back light source in a white color on the liquid crystal panel is provided with a better light rendering effect.  
      b) Description of the Prior Art  
      A typical structure of an assembled device of a liquid crystal panel and a back light source is disclosed in the Taiwan Utility Model Reg. No. M245448, “Light Module of A Liquid Crystal Display,” wherein the light emitting diode used by the light source is composed of an ultraviolet (UV) LED and illumination materials which can emit red, blue, and green light (R, B, G). Its drawback is that the ultraviolet light will create damage to the structure of epoxy resin which is used widely, thereby causing a problem of attenuation to the white light, and enabling a weak brightness to the white light. In particular, the cladding layer of the aforementioned invention is made by mixing illumination powders of red, green, and blue colors. Therefore, another drawback is that the proportions of these three colors and the manufacturing process are difficult to control. Moreover, the claim item 5 of the aforementioned invention discloses that the light emitter diode is a blue light LED, and the illumination powders are red and green light illumination materials. However, it is found that it is difficult to control the proportions of red and green illumination powders and the manufacturing process, so as to hard to control the uniformity of the mixed light (or the white light), thereby causing an inferior light rendering effect to the white light manifested by the liquid crystal panel.  
      In the Taiwan Utility Model Reg. No. M251143, “Light Device of a Liquid Crystal Screen,” the light source uses a blue light or UV light with the wavelength between 202 nm and 500 nm as a single light source. However, the light source is in short of red light in the spectrum. Therefore, the white light mixed by exciting the illumination board (or the mixed light) is not provided with a good rendering effect and uniformity, and is defined as an impure white light by human eyes.  
      The Taiwan Utility Model Reg. No. 1228837, “Light Emitting Device,” invented by the present inventor is a white light LED, which uses a blue light and a red light emitting chips (LED) as two light sources. The illumination layer is glued on the blue light chips and the red light chips, and is excited by a light source to emit a green light which is mixed with the blue and red light to form the white light. The invention effectively overcomes the problem of hard to control the proportions of illumination powders of different colors and the manufacturing process as described in the aforementioned invention, and uses the red light LED to replace a conventional red illumination powder, so as to enable the material of illumination layer to be a single color material. This kind of design can solve the problem of hard to control the mixing proportions of different colors and the manufacturing process, and can further control the wavelength of single excited light (i.e., the wavelength of green light). In addition, the invention uses a mixing of the red light emitted from the red light LED, the excited light, and the blue light, to obtain a white light with a better rendering effect. However, the implementation of invention is limited to the new design of white light LED, and there is still no extended implementation applied to the assembled device of a liquid crystal panel and a back light module.  
     SUMMARY OF THE INVENTION  
      The primary object of present invention is to provide an assembled device of a light module and a liquid crystal panel, wherein a white light transmitted from a back light source is provided with a rendering effect and uniformity which are easy to control and are of a good quality.  
      Another object of the present invention is to provide an assembled device of a light module and a liquid crystal panel, wherein an illumination layer used for the back light module is a light emitting material, such that the wavelength of excited light can be easily controlled, thereby achieving a function of easily controlling the rendering effect and uniformity of the white light from back light source of the liquid crystal panel.  
      Still another object of the present invention is to provide an assembled device of light module and a liquid crystal panel, wherein the device can be replaced by easily exchanging a light diffusion plate coated with an illumination layer.  
      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 perspective view upon assembling the present invention.  
       FIG. 2  shows a perspective view upon assembling another implementation of the present invention.  
       FIG. 3  shows a local cross sectional view of the present invention.  
       FIG. 4  shows a local cross sectional view of another implementation of the present invention.  
       FIG. 5  shows a local cross sectional view of a third implementation of the present invention.  
       FIG. 6  shows a local cross sectional view of a fourth implementation of the present invention.  
       FIG. 7  shows a local cross sectional view of a fifth implementation of the present invention.  
       FIG. 8  shows a local cross sectional view of a sixth implementation of the present invention.  
       FIG. 9  shows a local cross sectional view of a seventh implementation of the present invention.  
       FIG. 10  shows a local cross sectional view of an eight implementation of the present invention.  
       FIG. 11  shows a local cross sectional view of a ninth implementation of the present invention.  
       FIG. 12  shows a local cross sectional view of a tenth implementation of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIG. 1 ,  FIG. 2 ,  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6 ,  FIG. 7 , and  FIG. 8 , the present invention is to provide an assembled device of a light module and a liquid crystal panel comprising a liquid crystal panel  10  whose bottom surface  11  is provided with a light module  20  which includes a circuit board  21  on which are welded at least more than one blue light chip  32  as a blue light B emitting source, and more than one red light chip  34  as a red light R, next to the blue light chip  32 , as a red light R emitting source. A light emitting illumination layer  40  is made by uniformly mixing an illumination powder with a transparent glue, and is located on the blue light chip  32  and red light chip  34 .  
      Accordingly, a light diffusion plate  12  is located between the light module  20  and the liquid crystal panel  10 , and the illumination layer  40  can be uniformly coated on an upper surface  121  or a lower surface  122  of the light diffusion plate  12 . An adhesive layer  124  is located at the lower surface  122  of light diffusion plate  12  for being attached to a frame  211  at a periphery of circuit board  21  (as shown in  FIG. 3 ).  
      Accordingly, the blue light chip  32  and the red light chip  34  are located in a slot  61  of a same light reflection cap  60  whose pins  62 ,  64  of two electrodes are welded on the circuit board  21 , and the transparent glue  45  is filled in the slot  61 .  
      Accordingly, the blue light chip  32  and the red light chip  34  are located in slots  61  of light reflection caps  60 , ( 60 ), respectively, and pins  62 ,  64  of electrodes of the two light reflection caps  60 , ( 60 ) are welded on the circuit board  21 , respectively. A pitch L between the two light reflection caps  60 , ( 60 ) is controlled to be within 1 mm (as shown in  FIG. 5 ). A transparent glue  45  is filled in the slots  61  of two light reflection caps  60 , ( 60 ), and on a surface of the circuit board  21 .  
      Accordingly, one or two or three combinations from the following mixtures can be chosen as a material of illumination powder in the illumination layer  40 : the aluminum garnet series activated by plutonium and containing Y and Al (YAG:Ce 3+ ), the garnet series activated by europium (YAG:EU 2+/3+ ), and the garnet series activated by terbium (YAG:Tb 3+ ).  
      Accordingly, a transparent light enhancing membrane  125  or a piece of prism used for enhancing light is added between the liquid crystal panel  10  and the light diffusion plate  12  (as shown in  FIG. 12 ).  
      Accordingly, the plural and neighboring blue light chips  32  and red light chips  34  are welded on the circuit board  21  in multiple rows of one-dimensional array (as shown in  FIG. 2 ).  
      Referring to  FIG. 1 , a liquid crystal panel  10 , a light diffusion plate  12 , and a light module  20  are in a rectangular shape with a smaller area, which can be applied to a small-scale liquid crystal screen. On the other hand, a liquid crystal panel  10 , a light diffusion plate  12 , and a light module  20  as shown in  FIG. 2  are in a rectangular shape with a larger area, which can be applied to a large-scale liquid crystal screen.  
      Referring to  FIG. 3 , a light diffusion plate  12  is a transparent plastic membrane or a thin sheet, whose upper surface  121  is uniformly coated with an illumination layer  40 , and whose lower surface  122  is uniformly coated with an adhesive layer  124 . A frame  211  is located at a periphery of circuit board  21 , and the adhesive layer  124  is attached on the frame  211 . In addition, the illumination layer  40  coated on the upper surface  121  of light diffusion plate  12  can be fitted on a bottom surface  11  of a liquid crystal panel  10 . Naturally, the illumination layer  40  can be also coated on the upper and lower surfaces  121 ,  122  of light diffusion plate  12  (not shown in the drawing).  
      A blue light chip  32  is located in a slot  61  of independent light reflection cap  60 , and a red light chip  34  is located in a slot  61  of another independent light reflection cap ( 60 ). A pitch L of every neighboring light reflection caps  60 , ( 60 ) is controlled to be about 1 mm. A transparent glue  45  is sealed in two slots  61 , ( 61 ) separately, so as to package the blue light chip  32  and the red light chip  34 . Pins  62 ,  64  of positive and negative electrode enable the blue light chip  32  and red light chip  34  to emit a blue light B and a red light R simultaneously, by a function of electrodes. The blue light B and red light R transmits out of the transparent glue  45 , the adhesive layer  124 , the light diffusion plate  12 , the illumination layer  40 , and the liquid crystal panel  10 , respectively, wherein the blue light B is primarily used to excite the illumination layer  40  to emit an excited light G with a wavelength between 500 nm and 570 nm, which is defined as a green light. The excited light G, the blue light B, and the red light R transmit out of the liquid crystal panel  10  and constitute into a mixed light, which is defined as a white light W. The white light W forms a back light source of the liquid crystal panel  10 .  
      Referring to  FIG. 4 , an adhesive layer  124  of light diffusion plate  12  can form a square frame to be attached on a frame  211  of circuit board  21 , so as to save an area of adhesive layer  121  as shown in  FIG. 3 .  
      Referring to  FIG. 5 , an illumination layer  40  is coated on a lower surface  122  of light diffusion plate  12 , and a transparent adhesive layer  124  is coated on a lower surface of illumination layer  40 , such that a blue light B and a red light R can transmit from the adhesive layer  124 , and the illumination layer  40  can be excited by the blue light B to generate an excited light G. The excited light G, the blue light B, and a red light R transmit out of a liquid crystal panel  10  and constitute into a mixed light, which is defined as a white light W. The white light W serves as a back light source of a liquid crystal screen.  
      Referring to  FIG. 6 , a blue light chip  32  and a red light chip  34  are directly welded on a circuit board  21  by pins  62 ,  64  of positive and negative electrodes, and a transparent glue  45  is filled on a surface of circuit board  21  to completely package the blue light chip  32  and the red light chip  34 . An adhesive layer  124  is attached on a surface of transparent glue  45 . A blue light B and a red light R emitted from the blue light chip  32  and red light chip  34  transmit out of the transparent glue  45 , the adhesive layer  124 , a light diffusion plate  12 , an illumination layer  40 , and a liquid crystal panel  10 , wherein the blue light B is used to excite the illumination layer  40  to generate an excited light G. The excited light G and the blue, red lights B, R are mixed to form into a mixed light, which is defined as a white light W.  
      Referring to  FIG. 7 , a blue light and a red light chip  32 ,  34  are installed in a slot  61  of a same light reflection cap  60  and are packaged by a transparent glue  45  at the same time. The blue light and the red light chips  32 ,  34  emit a blue and a red light B, R which transmit out of the transparent glue  45 , a light diffusion plate  12 , an illumination layer  40  and a liquid crystal panel  10 , wherein the blue light B is primarily used to excite the illumination layer  40  to generate an excited light G to be mixed with the blue and red lights B, R for forming a mixed light (i.e., a white light W), as a back light source of liquid crystal screen.  
      Referring to  FIG. 8 , an illumination layer  40  is filled in a slot  61  of light reflection cap  60 , to package a blue light chip  32 ; whereas a transparent glue  45  is filled in a slot  61  of another light reflection cap  60 , to package a red light chip  34 . A transparent light diffusion plate  12  is located above the light reflection cap  60 , such that an excited light G will be generated by exciting the illumination layer  40  with a blue light B, and will transmit out of a light diffusion plate  12  and a liquid crystal panel  10 . In addition, a red light R also transmits out of the transparent glue  45 , the light diffusion plate  12 , and the liquid crystal panel  10 , so as to mix the blue, red, and excited lights (B, R, G), thereby forming a mixed light.  
      Referring to  FIG. 9 , a blue light chip  32 , a red light chip  34 , and an illumination layer  40  are installed in a slot  52  and packaged by a bulb-shape transparent glue  45 , and a mixed white light W transmits out of a light diffusion plate  12 , wherein a main wiring frame  50 , and pins of electrodes  56 ,  55  are welded on a circuit board  21 .  
      Referring to  FIG. 10 , a blue light chip  32  and a red light chip  34  are installed in a slot  61  of light reflection cap  60 , whereas a transparent glue  45  is filled in the slot  61  and packages the blue light chip  32  and the red light chip  34 . When the blue and red light chips  32 ,  34  emit a blue light B and a red light R, the lights will transmit out of the transparent glue  45 . A material in light diffusion plate  12  is uniformly mixed into an illuminator which will be excited to an excited light G. Next, a white light W is formed by mixing the excited light G, the blue light B, and the red light R, and transmits out of a liquid crystal panel  10 .  
      Referring to  FIG. 11 , an illumination layer  40  is filled in a slot  61  of light reflection cap  60  and further packages a blue light chip  32  and a red light chip  34 . The blue light chip  32  and the red light chip  34  emit a blue light B and a red light R to excite the illumination layer  40  to generate an excited light G which will mix with the blue light B and the red light R to form a white light W transmitting out of a light diffusion plate  12  and a liquid crystal panel  10 .  
      Referring to  FIG. 12 , a layer of light enhancing membrane  125  or a piece of prism used for enhancing light can be added on an upper surface  121  of light diffusion plate  12  according to a requirement of designer, which is also an effective implementation of the present invention.  
      The essential features of present invention lie in that the blue light chip  32  and the red light chip  34 , which are mutually independent chips, are used as the back light source of liquid crystal panel  10 , and a single color illumination material is further chosen as the illumination layer  10 , for example, YAG:Ce 3+  or YAG:EU 2+/3+  or YAG:Tb 3+  of a same color, or a combination of one or two or three kinds of those materials. Accordingly, the problem of considering a proportion of mixing with illumination powders of other different colors does not exist, and the color of light enabled by the illumination layer  40  of a single material is defined as a green light with a wavelength between 500 nm and 570 nm. Therefore, it is easy control the wavelength of excited light G (i.e., defined as the green light) generated when the illumination layer  40  is excited by the blue light B.  
      The red light chip  34  is a light emitting diode, and the blue light chip  32  is also a light emitting diode. Therefore, by a means of circuit control, the red light chip  34  and the blue light chip can be controlled to emit lights simultaneously, and strength of light emitting can also be controlled, such that the rendering of white light W can be initiated simultaneously.  
      Referring to  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6 , and  FIG. 7 , when a light diffusion plate  12  and an illumination layer  40  is aging due to a long term interaction of light and electricity, such that a white light W is not provided with a good rendering effect, the entire light diffusion plate  12  containing the illumination layer  40  can be replaced. By an upward force with a human finger, the entire light diffusion plate  12  containing the illumination layer  40  can be torn off the circuit board  21  by a means of its adhesive layer  124 , and a new light diffusion plate  12  containing the illumination layer  40  can be attached to the circuit board  21  with its adhesive layer  124 , to achieve an object of exchanging with a new product, thereby maintaining a new status of rendering effect of the white light W of liquid crystal panel  10 .  
      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.