Patent Publication Number: US-2007116897-A1

Title: Liquid crystal display apparatus

Description:
BACKGROUND OF THE INVENTION  
      1. Field of Invention  
      The invention relates to a flat display apparatus and, in particular, to a liquid crystal display apparatus.  
      2. Related Art  
      Recently, electronic technology has been progressing rapidly, and portable electronic products are diversifying, resulting in increasing demands on the display apparatuses for light weight, compactness, and energy efficiency. Liquid crystal display apparatuses, which are among the most popular display apparatuses, have the advantages of low power consumption, low heat generation, light weight, and no radiation emission, and thus are used in various kinds of electronic products to replace the conventional CRT display (Cathode Ray Tube Display).  
       FIG. 1  shows a conventional liquid crystal display apparatus. As shown in  FIG. 1 , a liquid crystal display apparatus  1  mainly includes a backlight module  11 , a first polarizer  12 , a second polarizer  13 , a pair of substrates  14 ,  14 ′, a liquid crystal layer  15 , and a color filter  16 . The backlight module  11  emits light, and the light reaches the first polarizer  12 . By selection of the first polarizer  12 , only a part of the light polarized in a first predetermined direction can pass through the substrates  14 ,  14 ′, which have the liquid crystal layer  15  disposed therebetween. The arrangement of the liquid crystal molecules in the liquid crystal layer  15  can be changed by driving the liquid crystal layer  15 . Thus, when the light passes through the liquid crystal layer  15  and reaches the second polarizer  13 , the polarization direction of the light may be turned to a second predetermined direction. Only the light in the second predetermined direction can pass through the second polarizer  13  and then reach the color filter  16  disposed on the glass substrate  17 . When the light passes through the R, G, or B pixel of the color filter  16 , the user can obtain the desired color image based on the visual persistence.  
      In the prior art, cold cathode fluorescent lamps (CCFLs) are usually used to construct the backlight module  11  of the liquid crystal display apparatus  1 . As shown in  FIG. 2 , a conventional CCFL  20  includes a glass tube  21 , two electrode layers disposed at two ends of the glass tube  21 , and a phosphor layer  23  disposed on the inner wall of the glass tube  21 . The glass tube  21  is filled with mercury steam and mixed inert gases such as xenon and argon, which are used as the discharge medium. When the CCFL  20  is lighted, the electrode layer  22 , which is connected to the power source through the wire  221 , releases electrons. Then, the electrons are speeded by the electric field. By collision of the electrons and the discharge medium, the discharge medium turns to an excited state. After releasing ultraviolet light, the discharge medium may return to a ground state. The released ultraviolet light is absorbed by the phosphor layer  23 , and then the phosphor layer  23  emits visible light.  
      The CCFL  20  has a spectrum as shown in  FIG. 3 . The three major peaks are respectively representing the bandwidths of blue light, green light and red light. As shown in  FIG. 3 , the visible light emitted from the phosphor of the CCFL further includes the bandwidths of other colors which are the minor peaks indicated by the arrows. The minor peak (about 560 nm to 590 nm) located between the red light and green light usually occur due to the disposition of the mercury steam and green phosphor in the CCFL  20 . This minor peak usually decreases the purity of red light and green light of the CCFL and thus reduces the color saturation of the liquid crystal display apparatus.  
      Therefore, it is an important subject of the invention to provide a liquid crystal display apparatus with the CCFL as the backlight module that can reduce the light of the minor peaks.  
     SUMMARY OF THE INVENTION  
      In view of the foregoing, the invention is to provide a liquid crystal display apparatus having improved color saturation.  
      To achieve the above, the invention discloses a liquid crystal display apparatus, which includes a color filter. The liquid crystal display apparatus is characterized in that the color filter is doped with a spectrum absorbing material. The spectrum absorbing material has at least one absorbing peak between 560 nm and 590 nm.  
      As mentioned above, the liquid crystal display apparatus of the invention includes a spectrum absorbing material doped in the color filter for absorbing light of 560 nm to 590 nm, which is a color of light other than red, green or blue light. Compared with the prior art, the liquid crystal display apparatus of the invention includes the color filter doped with the spectrum absorbing material for absorbing light of minor peaks, so that the color saturation of the liquid crystal display apparatus can be improved. This improvement can induce the customer to by our products, and thus increase the sale amount of the products. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein:  
       FIG. 1  is a schematic view showing the conventional liquid crystal display apparatus;  
       FIG. 2  is a schematic view showing the conventional CCFL;  
       FIG. 3  is a schematic view showing the spectrum diagram of the light emitted from the CCFL;  
       FIG. 4  is a schematic view showing a liquid crystal display apparatus according to a preferred embodiment of the invention;  
       FIG. 5  is a schematic view showing a color filter of the liquid crystal display apparatus according to the embodiment of the invention; and  
       FIG. 6  is a schematic view showing an absorption spectrum diagram of a spectrum absorbing material S. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.  
      Please refer to  FIG. 4  to  FIG. 6 , illustrating a liquid crystal display apparatus according to a preferred embodiment of the invention.  
      With reference to  FIG. 4 , a liquid crystal display apparatus  30  includes a color filter  31 , which is doped with a spectrum absorbing material S. The spectrum absorbing material S has at least one absorbing peak between 560 nm and 590 nm.  
      With reference to  FIG. 5 , the color filter  31  includes a black matrix  311  and a plurality of color photoresistors  312 . The black matrix  311  defines a plurality of sub-pixel areas (R, G, and B). The color photoresistors  312  are formed on the sub-pixel areas (R, G, and B) to cover part of the black matrix  311 . The spectrum absorbing material S is doped into at least one of the color photoresistors  312 . If the spectrum absorbing material S is, for example, Neodymium Oxide (Nd2O3), it may be doped into the green photoresistors or the red photoresistors.  
      In this embodiment, the black matrix  311  and the color photoresistors  312  may be disposed on a transparent substrate  313 , and then a transparent conductive file  314  covers the black matrix  311  and the color photoresistors  312 . The black matrix  311  is usually made of chromium or chromium oxide. The color photoresistors  312  are usually composed of resin, which is combined with pigment or dye of different colors and then doped with the spectrum absorbing material S.  
      With reference to  FIG. 4  again, the liquid crystal display apparatus  30  may further include a backlight module  40 , which includes a lamp  41 .  
      Moreover, the liquid crystal display apparatus  30  may further include a first polarizer  32 , a second polarizer  33 , two substrates  34 ,  34 ′, and a liquid crystal layer  35 . In this embodiment, the color filter  31 , the first polarizer  32 , the second polarizer  33 , the substrates  34 ,  34 ′, and the liquid crystal layer  35  construct a liquid crystal panel module  50 . The backlight module  40  and the liquid crystal panel module  50  construct the liquid crystal display apparatus  30 .  
      The backlight module  40  emits light, and the light reaches the first polarizer  32 . By selection of the first polarizer  32 , only a part of the light polarized in a first predetermined direction can pass through the substrates  34 ,  34 ′, which have the liquid crystal layer  35  disposed therebetween. The arrangement of the liquid crystal molecules in the liquid crystal layer  35  can be changed by driving the liquid crystal layer  35 . Thus, when the light passes through the liquid crystal layer  35  and reaches the second polarizer  33 , the polarization direction of the light may be turned to a second predetermined direction. Only the light polarized in the second predetermined direction can pass through the second polarizer  33  and then reach the color filter  31 . When the light passes through the R, G, or B pixel of the color filter  31 , the user can perceives the desired color image based on visual persistence.  
       FIG. 6  shows the absorption spectrum diagram of the spectrum absorbing material S, which dopes in the color filter  31 . With reference to  FIG. 6 , the spectrum absorbing material S has an absorbing peak located between 560 nm and 590 nm. Thus, after the light enters the color filter  31 , the spectrum absorbing material S of the color filter  31  can absorb the light from 560 nm to 590 nm, which corresponds to the colors between green and red. Therefore, the color saturation of the liquid crystal display apparatus  30  can be improved.  
      In summary, the liquid crystal display apparatus of the invention includes a spectrum absorbing material doped in the color filter for absorbing light of 560 nm to 590 nm, which corresponds to colors of light other than red, green, or blue light. Compared with the prior art, the liquid crystal display apparatus of the invention includes the color filter doped with the spectrum absorbing material for absorbing light of minor peaks, so that the color saturation of the liquid crystal display apparatus can be improved. This improvement can induce the customer to by our products, and thus increase the sale amount of the products.  
      Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.