Abstract:
A light-emitting module includes a plurality of lamp units and a plurality of LED units. The lamp unit generates first non-white colored light. The LED unit generates second colored light. Each LED unit is disposed between the lamp units. The first non-white colored light and the second colored light are mixed to generate third colored light. A backlight module and a liquid crystal display (LCD) are also disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 096119779 filed in Taiwan, Republic of China on Jun. 1, 2007, the entire contents of which are hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The invention relates to a light-emitting module, a backlight module and a liquid crystal display (LCD). 
         [0004]    2. Related Art 
         [0005]    The liquid crystal display (LCD) panels lack the self-lighting property, so the backlight modules have become an important subject in the development of the LCD technology. In the prior art, a cold cathode fluorescent lamp (CCFL) has the advantages of the low cost and high lighting efficiency, and is thus widely adopted as a light source for the backlight module. The lighting principle of the CCFL is to generate ultra-violet rays by way of high-voltage electrode discharge, and the ultra-violet rays excite red, green and blue fluorescent materials of the lamp. Then, the fluorescent materials respectively emit red, green and blue colored light, which can be mixed to produce the white light. 
         [0006]    An upper portion of  FIG. 1  is a schematic illustration showing wavelength ranges of light rays emitted from a white-light CCFL. A lower portion of  FIG. 1  is a schematic illustration showing wavelength ranges of light rays emitted from red, green and blue light emitting diodes (LEDs). As shown in the upper portion of  FIG. 1 , W 1 , W 2  and W 3  respectively represent a red light band, a green light band and a blue light band of the CCFL. The white-light CCFL has red, green and blue fluorescent materials respectively emitting red, green and blue light, which are mixed to form white light. In the lower portion of  FIG. 1 , W 4 , W 5  and W 6  respectively represent red, green and blue light bands outputted from the LEDs. To compare with the upper portion and the lower portion of  FIG. 1 , the bands W 1 , W 2  and W 3  of each colored light in the white-light CCFL have the peaks P 1  to P 3  of the main colored light as well as the peaks P 4  to P 11  of the other unnecessary colored light. Thus, the saturation of the main colored light is insufficient and the display gamut range is reduced. 
         [0007]    In addition, the energy of the ultra-violet ray in the CCFL is about 4.88 eV (electron volts). The energy is about 1.96 eV after the red fluorescent material is excited to emit light. Hence, the energy loss ratio is about (4.88−1.96)/4.88×100%=59.8%. 
         [0008]    In addition, the energies, which are generated after the green and blue fluorescent materials are excited to emit light, are 2.33 eV and 2.7 eV, respectively. Therefore, the energy loss ratios are respectively 52.2% and 43.6%. Correspondingly, the energy loss ratio of the red fluorescent material is also higher than those of the green and blue fluorescent materials. 
         [0009]    To improve the above-mentioned problem, a red LED is added to the backlight module. The highly saturated red light outputted from the red LED can enhance the color saturation of the red light outputted from the backlight module. 
         [0010]    In the conventional improved method, however, the CCFL for outputting the white light still serves as the main lighting unit. Thus, the problem of energy loss of the red fluorescent material still cannot be solved. Furthermore, the CCFL for outputting the white light still outputs the red light with the insufficient saturation so that the red LED cannot function normally. 
         [0011]    Therefore, it is an important subject to provide a lighting unit, a backlight module and a LCD capable of enhancing the color saturation and reducing the energy loss. 
       SUMMARY OF THE INVENTION 
       [0012]    In view of the foregoing, the invention is to provide a lighting unit, a backlight module and a LCD with the enhanced color saturation and the reduced energy loss. 
         [0013]    To achieve the above, the invention discloses a light-emitting module, which includes a plurality of lamp units and a plurality of LED units. The lamp units generate a first non-white colored light, and the LED units generate a second colored light. Each of the LED units is disposed between the lamp units. The first non-white colored light and the second colored light are mixed to generate a third colored light. 
         [0014]    To achieve the above, the invention also discloses a backlight module, which includes a housing, a plurality of lamp units and a plurality of LED units. The housing has a first surface and a second surface oppositely disposed to the first surface. The lamp units are positioned in the housing and disposed on the first surface. Each of the lamp units generates a first non-white colored light. The LED units are disposed between the lamp units for generating a second colored light. The first non-white colored light and the second colored light are complementary and mixed to generate a third colored light. 
         [0015]    To achieve the above, the invention further discloses a liquid crystal display (LCD), which includes a LCD panel and a backlight module disposed on one side of the LCD panel. The backlight module includes a housing, a plurality of lamp units and a plurality of LED units. The housing has a first surface and a second surface. The lamp units are positioned in the housing and disposed on the first surface for generating a first non-white colored light. The LED units are disposed between the lamp units for generating a second colored light. The first non-white colored light and the second colored light are complementary and mixed to generate third colored light. 
         [0016]    As mentioned above, the CCFL and the LED are simultaneously disposed in the light-emitting module or the backlight module according to the invention, and the colors of the light rays outputted from the CCFL and LED are complementary. 
         [0017]    Compared with the prior art, since the colors of the light rays outputted from the CCFL and LED are complementary, mixing the colors of light can form a white light. Thus, the LED can develop the function effectively, and the energy loss generated by the unessential fluorescent material in the CCFL may also be reduced. Therefore, the overall lighting efficiency of the light-emitting module can be enhanced, and the color saturation and the gamut range also be enhanced when the LCD is displaying. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    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: 
           [0019]      FIG. 1  is a schematic illustration showing wavelength ranges of light rays emitted from red, green and blue LEDs and a white light CCFL; 
           [0020]      FIG. 2  is a schematic illustration showing a LCD according to a first embodiment of the invention; 
           [0021]      FIG. 3  is a schematic illustration showing a LCD according to another aspect of the first embodiment of the invention; and 
           [0022]      FIG. 4  is a schematic illustration showing a LCD according to a second embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    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. 
       First Embodiment 
       [0024]    Referring to  FIG. 2 , a LCD  1  according to a first embodiment of the invention includes a LCD panel  2  and a backlight module  3 . The backlight module  3  is disposed under the LCD panel  2  and has a housing  31 , a lamp unit  32  and a LED unit  33 . The housing  31  has a first surface  311  and a second surface  312 , the lamp unit  32  is disposed opposite to the first surface  311  of the housing  31 , and the LED unit  33  is disposed adjacent to the lamp unit  32 . 
         [0025]    Also, in this embodiment, the backlight module  3  further includes a reflecting unit  34 , a circuit board  35  and a diffuser  36 . The reflecting unit  34  is disposed between the first surface  311  of the housing  31  and the lamp unit  32  and has a bottom surface, which is an uneven surface  341 . The lamp unit  32  is disposed in a concave portion C on the uneven surface  341 , while the LED unit  33  is disposed in a convex portion R on the uneven surface  341 . In addition, as shown in a LCD  1 A of  FIG. 3 , the bottom surface of a reflecting unit  34 A may also be an even surface so that the manufacturing cost of the reflecting unit  34 A is reduced. 
         [0026]    As shown in  FIG. 2 , the circuit board  35  may be disposed on the second surface  312  of the housing  31 , or disposed between the first surface  311  of the housing  31  and the reflecting unit  34 . In this embodiment, the circuit board  35  is disposed on the second surface  312  of the housing  31 , and the circuit board  35  is electrically connected to the lamp unit  32  and the LED unit  33 . In addition, if the circuit board  35  is disposed between the reflecting unit  34  and the lamp unit  32 , the LEDs of the LED unit  33  may also be electrically connected to the circuit board  35  by surface mount technology (SMT) method. However, the LEDs may also be electrically connected to the circuit board  35  according to other manners. 
         [0027]    The diffuser  36  is disposed on the lamp unit  32  and the LED unit  33 , and makes the light outputted from the lamp unit  32  and the LED unit  33  become more uniform by way of scattering. 
         [0028]    In order to enhance the saturation of each colored light among the white light formed by mixing the light of the lamp unit  32  and the LED unit  33 , a CCFL  321  of the lamp unit  32  may cooperate with a LED  331  of the LED unit  33 . 
         [0029]    In this embodiment, the CCFL  321  only has the green and blue fluorescent materials, so the light outputted to form a cyan light by mixing the green light and the blue light. In order to make the mixed light outputted from the lamp unit  32  and the LED unit  33  become the white light, the LED  331  in the LED unit  33  is a red LED for outputting light, which has a wavelength range from 600 to 700 nm and is complementary to the yellow light. 
         [0030]    Compared the cyan-light CCFL  321  of this embodiment with the conventional white-light CCFL, the total energy loss in the conventional white-light CCFL is about 
         [0000]      ⅓×59.8%+⅓×52.2%+⅓×43.6%=51.87%. 
         [0000]    In addition, the total energy loss in the cyan-light CCFL  321  of this embodiment is about 
         [0000]      ½×52.2%+½×43.6%=47.9%. 
         [0000]    Thus, about 4% of energy loss is reduced after the red fluorescent material is eliminated. 
         [0031]    In addition, as for the contribution degree to the human eyes, the ratio of the contribution degree of the red light to that of the green light and that of the blue light in the conventional white-light CCFL is about 
         [0000]      (2×:5×:1×), 
         [0000]    wherein x is a constant. In the cyan-light CCFL  321  of this embodiment, the energy received by the green and blue fluorescent materials is increased by ½ because the red fluorescent material is removed. Thus, the ratio of the contribution degree of the green light to that of the blue light is also increased to 
         [0000]      7.5×:1.5×. 
         [0000]    The contribution degree of the red light may be adjusted using the red LED  331 . In order to keep the same ratio, the ratio of the contribution degree of the red light to that of the green light and that of the blue light may be increased to 
         [0000]      3×:7.5×:1.5×. 
         [0032]    Thus, the contribution degrees of the green and blue light are increased under the same driving power. In other words, if the original contribution degree is kept, the power-saving effect can be achieved using the lower driving power. 
         [0033]    In addition, when the CCFL  321  only has the red and blue fluorescent materials, the CCFL  321  outputs a magenta light, and the LED  331  is changed to a green-light diode for outputting light having a wavelength range from 500 to 580 nm. When the CCFL  321  only has the red and green fluorescent materials, the CCFL  321  outputs a yellow light, and the LED  331  is changed to a blue-light diode for outputting light having a wavelength range from 400 to 500 nm. 
         [0034]    In brief, one portion of three primary colors (red, green and blue) is provided by the CCFL, and the LED provides the other portion of the three primary colors. Then, the two portions are mixed to form the white light. 
         [0035]    In the above-mentioned embodiment, the lamp unit  32  and the LED unit  33  may also be incorporated and thus regarded as a light-emitting module, which may be used individually. 
       Second Embodiment 
       [0036]    As shown in  FIG. 4 , a LCD  1 B according to a second embodiment of the invention is different from the LCD of the first embodiment in that a CCFL  321 B only has two colored fluorescent materials, and a LED unit  33 B has two LEDs  331 B and  332 B for outputting different colors of light. 
         [0037]    If the CCFL  321 B is the red fluorescent material, the CCFL  321 B outputs the red light, and the LEDs  331 B and  332 B respectively output the green light and the blue light. The three colors of light are then mixed to form the white light. 
         [0038]    Also, if the CCFL  321 B is the green fluorescent material, the CCFL  321 B outputs the green light, and the LEDs  331 B and  332 B respectively output the red light and the blue light. The three colors of light may also be mixed to form the white light. 
         [0039]    In addition, if the CCFL  321 B is the blue fluorescent material, the CCFL  321 B outputs the blue light, and the LEDs  331 B and  332 B respectively output the red light and the green light. The three colors of light may also be mixed to form the white light. 
         [0040]    In summary, the CCFL and the LED are simultaneously disposed in the light-emitting module or the backlight module according to the invention. Also, the color of the fluorescent material in the CCFL can be adjusted, and the LEDs with different colors are provided, and the colors of the outputted light rays are complementary colors. 
         [0041]    Compared with the prior art, two different fluorescent materials or one fluorescent material is disposed in the CCFL of the invention so that the CCFL outputs the light ray which is not white, and one LED or two LEDs are provided to output the light which is complementary to that the light outputted by the CCFL. Then, the while light can be formed by mixing the colors of light. Thus, the LED can develop the function effectively, and the energy loss generated by the unessential fluorescent material in the CCFL may also be reduced. Therefore, the overall lighting efficiency of the light-emitting module can be enhanced, and the color saturation and the gamut range are enhanced when the LCD is displaying. In addition, the contribution degree of each colored light to human eyes can be enhanced while the power can be saved. 
         [0042]    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.